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Mustang V1.0.39 · Mustang 2 V1.0.50 · Web Remote V1.0.87 · Mobile Remote V1.0.66 · as of 17 Oct 2026

Mustang Manual

The complete operating manual for the Mustang 2 station: the T41 radio itself, the Raspberry Pi 5 that drives its Touch Display, and the web and phone remotes that reach it over the home network. One chapter per piece – what it is, how to operate it, and every control it has.

Mustang Manual

Introduction

The Mustang 2 station is four pieces working together, and this manual has one chapter for each:

The T41 (Chapter 1) is the radio itself – a T41-EP SDR transceiver running the Mustang firmware. Every control that actually operates the radio lives here first: the tuning knobs, the Volume/Filter encoders, the front-panel buttons, and the Menu system that holds every setting the radio has, organized into 9 primary categories. Nothing downstream of the T41 can do anything the T41 itself can’t – the Pi and both remotes only ever send it the same button presses and knob turns the front panel would.

The Pi 5 (Chapter 2) is a Raspberry Pi 5 added alongside the Teensy 4.1 main board, driving a 7″ Raspberry Pi Touch Display 2 that mirrors the T41’s own screen and adds a mouse-driven toolbar in place of the Menu button. It talks to the Teensy over a serial link (PiLink), reading telemetry down and sending button presses and knob turns up – it is an add-on, not a dependency, and the radio works exactly the same with the Pi unplugged.

The Web Remote (Chapter 3) is a page the Pi serves to any browser on the home network, mirroring the same screen and sending the same commands as the Pi’s own toolbar, plus live receive audio, a virtual rotary dial for tuning/filter/volume, and keyboard control.

The Mobile Remote (Chapter 4), “Mustang Mobile,” is the phone-sized version of the same page, at /mobile: a denser toolbar grid, native phone pickers in place of dropdowns, and touch sliders standing in for the mouse wheel.

All four see and change the same radio at the same time, with no lock between them – a Menu pick from a phone shows up instantly on the T41’s own screen, the Pi, and every other open browser.

Chapter 1 · The T41

Overview

The T41 is a T41-EP SDR transceiver, built around a Teensy 4.1 doing all of the real-time audio, DSP and RF work. Every operating control – tuning, filtering, volume, mode, band, calibration, every Menu setting – lives on the Teensy and is reachable from its own front panel without anything else connected. The Pi 5 and the web/phone remotes (Chapters 2–4) are all just additional ways of sending the T41 the same button presses and knob turns its front panel sends; none of them add a capability the radio doesn’t already have on its own.

Front panel controls

Four encoder knobs do the moment-to-moment work of operating the radio:

• Center Tune – the main VFO knob. Turning it moves the tuned frequency by the current Course Tune increment; pressing it steps through the available increments.
• Fine Tune – a second tuning knob for small adjustments, at its own, smaller increment; pressing it steps through the fine-tune increments the same way.
• Volume – turns whichever of Audio Volume, AGC threshold, Mic Gain or Sidetone Volume is currently selected (the Settings pane’s “Vol:” label shows which); pressing the Volume button (VOLUME_BUTTON) cycles to the next one of the four.
• Filter – turns whichever edge of the receive filter is currently selected, Lo Cut or Hi Cut; pressing the Filter button (FILTER_BUTTON) toggles which edge that is. The same knob also drives a Menu setting’s value once a “Label: value” box is open, and (on the Audio Equalizer screen) a band’s level.

A row of dedicated buttons covers everything else: Band (up/down through the ham bands), Mode, Demod, Noise Reduction (cycles Off/Kim/Spectral/LMS), Zoom (spectrum/waterfall zoom, 1×–16×), Decode (CW decoder on/off), Select (confirms a Menu value or enters a highlighted item), Home and Spare (toggles between the primary 11-pane home layout and a secondary 5-pane one), plus the Menu button itself. PTT and the KEY jack (straight key or paddle, see CW Options) key the transmitter. In all, there are 22 front-panel buttons and the 4 encoders above; Menu > Front Panel Test (or the Diagnostics menu) lights up each button as it’s pressed and shows each encoder’s running turn count and direction – a quick way to check a front panel after reassembly without test equipment.

The Menu system

Press Menu to open it: the Filter knob’s left/right selects one of 9 primary categories, up/down selects an option within it, and the Volume/Filter knob (whichever the screen calls for) adjusts a selected “variable” option – one with a numeric or on/off value, shown in a red “Label: value” box with Select to confirm. A “function” option runs immediately when selected, with no value to adjust.

Mustang 2 uses the exact same menus, with a few additions, and the same Menu can also be opened from the Pi Touch Display and the web and phone remotes – see Chapter 2. Tags used below:

• Mustang 2 only in the Mustang 2 firmware.
• Pi & remotes only added by the Pi; only in the Pi Touch Display and web/phone remote menus, not on the radio itself.
• Greyed out on Pi & remotes shown but not selectable from the Pi or the remotes for now, because that screen hasn’t been built for them yet. It still works normally from the radio’s front panel.
• Also on Pi & remotes a screen that also opens on the Pi and the remotes.
• Own dropdown on the Pi and the remotes this whole menu has its own toolbar button instead of sitting under Menu — see the Pi 5’s toolbar.

Table of Contents

Menus

1. RF Options
2. CW Options
3. Microphone
4. Audio Options
5. Display
6. EEPROM
7. Calibration
8. Diagnostics
9. Sample Rate
10. Network (Pi screen only)

Settings

1. Settings Pane
2. CW Settings Pane

Menu Tree

• RF Options
  • SSB Power
  • CW Power
  • RX Attenuation
  • Antenna
  • RX DSP Gain Mustang 2
• CW Options Own dropdown: CW
  • WPM
  • Straight key
  • Keyer
  • Flip paddle
  • CW Filter
  • Sidetone volume
  • AT Grace (s)
  • CW Manual Mode
• Microphone Own dropdown: Mic
  • Mic gain
  • USB drive
  • USB RX level
• Audio Options Own dropdown: Audio
  • AGC Off
  • AGC Long
  • AGC Slow
  • AGC Medium
  • AGC Fast
  • Adjust Equalizers Also on Pi & remotes
  • Toggle Autonotch
  • Noise Reduction Off
  • Kim Noise Reduction
  • Spectral Noise Reduc.
  • LMS Noise Reduction
• Display Own dropdown: Display
  • Auto spectrum floor
  • Manual spectrum floor
  • Spectrum floor
  • Spectrum scale
  • Spectrum smoothing
  • Spectrum decay
  • Spectrum trace smoothing
  • Spectrum shadow on
  • Spectrum shadow off
  • Spectrum fill on Mustang 2
  • Spectrum fill off Mustang 2
  • Brightness Pi & remotes only
  • Freq Font Pi & remotes only
  • PI Spectrum Fill Pi & remotes only
  • PI Waterfall (2D / 3D) Pi & remotes only
  • PI Waterfall Speed Pi & remotes only
• EEPROM
  • Save data to storage
  • Load from SD card
  • Print data to Serial Greyed out on Pi & remotes
• Calibration
  • S meter level Also on Pi & remotes
  • Frequency Also on Pi & remotes
  • Receive IQ Also on Pi & remotes
  • Transmit IQ Also on Pi & remotes
  • Power Also on Pi & remotes
• Diagnostics
  • I2C BIT test Also on Pi & remotes
  • Restore receive EQ Greyed out on Pi & remotes
  • Buffer print Greyed out on Pi & remotes
• Sample Rate
  • 192 ksps
  • 176.4 ksps
• Network Pi screen only
  • Wi-Fi page (status, networks, password keyboard)

Item Details

RF Options

SSB Power(back to tree)

Transmit power (watts) for SSB mode, set per band. Range 0–20 W, 0.5 W steps.

CW Power(back to tree)

Transmit power (watts) for CW mode, set per band; internally converted to a TX attenuation value. Range 0–20 W, 0.5 W steps.

RX Attenuation(back to tree)

Attenuation added ahead of the receiver, per band, to prevent front-end overload on strong signals. Range 0–31.5 dB, 0.5 dB steps.

Antenna(back to tree)

Selects which antenna port (0–3) is used for the current band.

RX DSP Gain Mustang 2(back to tree)

Receive gain applied in the DSP, for all bands. Range −5.0 to +20.0 dB in 0.5 dB steps; shown on the Settings pane as “DSP Gain:”. Raise it if weak signals barely rise above the noise on the spectrum.

CW Options

WPM(back to tree)

CW keyer/decoder speed in words per minute. Range 5–50 WPM.

Straight key(back to tree)

Switches the key input to straight-key mode (no electronic keyer timing).

Keyer(back to tree)

Switches the key input to electronic-keyer (paddle) mode.

Flip paddle(back to tree)

Swaps the dit/dah paddle connections in software, for opposite-handed paddle wiring.

CW Filter(back to tree)

Selects one of the CW receive bandpass filter presets (index 0–5).

Sidetone volume(back to tree)

Volume of the CW sidetone (the tone heard while sending). Range 0–500.

AT Grace (s)(back to tree)

Seconds CW auto-tune holds its position after losing a confirmed signal lock before resuming its automatic search. Range 2–30 s.

CW Manual Mode(back to tree)

Turns off CW auto-tune's automatic frequency adjustment and pins the decoder's timing to the current WPM setting, for fully manual CW tuning.

Microphone

Mic gain(back to tree)

Microphone input gain for SSB transmit. Range −10 to +30.

USB drive(back to tree)

Transmit audio drive level applied to USB/digital-mode audio – the digital-mode equivalent of mic gain. Range 0–100.

USB RX level(back to tree)

Level of receive audio sent out over USB to a computer for digital modes. Range 0–100.

Audio Options

AGC Off(back to tree)

Disables Automatic Gain Control entirely.

AGC Long(back to tree)

Sets AGC response to its slowest attack/release.

AGC Slow(back to tree)

Sets AGC response to slow attack/release.

AGC Medium(back to tree)

Sets AGC response to medium attack/release.

AGC Fast(back to tree)

Sets AGC response to its fastest attack/release.

Adjust Equalizers Also on Pi & remotes(back to tree)

Opens the receive and transmit audio equalizer screen: 14 bands from about 200 Hz to 4 kHz, levels 0–100. On the radio, button 15 switches RX/TX, the Volume knob picks the band, the Filter knob sets its level, button 16 changes the step (1 or 10) and Home saves and exits.

Mustang 2 From V1.0.26 the same screen opens full-screen on the Pi and the remotes, with Edit RX / Edit TX, Cell ◀ ▶, Level − / +, Incr, Exit and Save & Exit; tap a bar to pick it. From V1.0.27, Exit (button 14 on the radio) puts both equalizers back the way they were and leaves without saving.

Toggle Autonotch(back to tree)

Turns the automatic notch filter (removes steady tones/heterodynes from receive audio) on or off.

Noise Reduction Off(back to tree)

Disables noise reduction processing.

Kim Noise Reduction(back to tree)

Enables the “Kim” noise-reduction algorithm.

Spectral Noise Reduc.(back to tree)

Enables spectral-subtraction noise reduction.

LMS Noise Reduction(back to tree)

Enables LMS (adaptive-filter) noise reduction.

Display

Auto spectrum floor(back to tree)

Lets the spectrum display automatically track and adjust its noise-floor baseline.

Manual spectrum floor(back to tree)

Switches to a fixed, manually-set noise floor (see Spectrum floor below).

Spectrum floor(back to tree)

Manual noise-floor baseline, per band, used when Auto spectrum floor is off. Range −100 to +100.

Spectrum scale(back to tree)

Spectrum/waterfall vertical scale, in dB per division – from 20 dB/division (least sensitive) down to 1 dB/division (most sensitive), across 17 steps.

Spectrum smoothing(back to tree)

Averages each point on the spectrum trace with this many neighboring bins on either side, smoothing the curve at the cost of frequency detail. 0 = off (raw trace); up to 10 (a 21-bin average).

Spectrum decay(back to tree)

Seconds the blue “shadow” trace (marks recent peaks) takes to fade back down to the live trace after tracking a peak. Range 0.5–20 s.

Spectrum trace smoothing(back to tree)

Eases the live green trace's frame-to-frame movement instead of snapping instantly to every new reading, for a steadier-looking trace. 0 s = off (original instant-snap behavior); range 0–0.3 s.

Spectrum shadow on(back to tree)

Shows the blue decaying-peak shadow trace behind the live spectrum trace.

Spectrum shadow off(back to tree)

Hides the blue decaying-peak shadow trace behind the live spectrum trace.

Spectrum fill on Mustang 2(back to tree)

Draws the radio’s spectrum trace filled in, graded green to yellow to red by signal strength. From V1.0.29 the radio always powers up with the fill off; pick this to turn it on until the next power-off.

Spectrum fill off Mustang 2(back to tree)

Draws the spectrum as an outline only. On a very strong or wide signal the filled trace can take long enough to draw that the audio drops out; turn the fill off if audio ever gets choppy. This is the power-up default from V1.0.29.

Brightness Pi & remotes only(back to tree)

Sets the Pi Touch Display 2’s backlight: 25, 50, 75 or 100%. Doesn’t change anything on the radio.

Freq Font Pi & remotes only(back to tree)

Style of the frequency readout on the Pi and the remotes: Original, Nixie (glowing orange wire digits in glass tubes, with a tube for each decimal point), VFD (green seven-segment) or Dot Matrix (blue 5×7 dots). Doesn’t change the radio’s own screen.

PI Spectrum Fill Pi & remotes only(back to tree)

On / Off (under PI Spectrum): turns the spectrum fill on or off on the Pi’s screen and the web and phone remotes together, separately from the radio’s own Spectrum fill setting above. Always starts Off when the Pi app starts.

PI Waterfall Pi & remotes only(back to tree)

2D / 3D (under PI Spectrum). 3D shows the newest spectrum row in front, with older rows stepping back — narrower and higher — and fading away, blue at the base up to yellow, orange and red on strong signals. With firmware V1.0.32 or later the 2D waterfall uses the radio’s own colour for every point, so the background noise is the same blue as on the T41.

PI Waterfall Speed Pi & remotes only(back to tree)

Fast / Medium / Slow / Very slow (under PI Spectrum): about 15, 7, 4 or 2 new waterfall rows a second, for both 2D and 3D. Short signals are never skipped at the slower speeds, and the spectrum trace above stays real-time.

EEPROM

Save data to storage(back to tree)

Saves all current settings to persistent storage (SD card/LittleFS) so they survive a reboot.

Load from SD card(back to tree)

Reloads settings from the SD card, discarding any unsaved changes.

Print data to Serial Greyed out on Pi & remotes(back to tree)

Dumps all current settings values to the Serial/USB debug console. Greyed out on the Pi and remotes for now; use the front panel.

Calibration

S meter level Also on Pi & remotes(back to tree)

Calibrates the S-meter/dBm reading, per band, against a known reference signal. Range −20 to +50. On the Pi and remotes it opens the usual value box (wheel or arrow keys, Select to confirm) with the S-meter still in view.

Frequency Also on Pi & remotes(back to tree)

Starts the reference-frequency calibration routine: tune to a reference station (WWV, CHU) first, set the modulation to SAM, then adjust the Factor until the Error reads under 1. Mustang 2 From V1.0.30 the same screen opens on the Pi and the remotes, with Factor − / +, Incr, Modulation, Exit (leave without saving) and Save & Exit; the Pi version adds a live spectrum.

Receive IQ Also on Pi & remotes(back to tree)

Starts the receive I/Q balance calibration routine (corrects phase/amplitude imbalance in the receiver). In Mustang 2 the same screen opens on the Pi and the web and phone remotes, with full control: amplitude and phase adjust, step size, auto-tune, band cycling and Save & Exit. The Pi screen also has Stop (ends an Auto sweep early) and Exit (leave without saving).

Transmit IQ Also on Pi & remotes(back to tree)

Starts the transmit I/Q balance calibration routine (minimises the opposite sideband). Mustang 2 From V1.0.30 the same screen opens on the Pi and the remotes, with IRR / dBc, the current-band values, the all-bands table and buttons for Amp, Phase, Atten, Incr, Auto, Stop (ends an Auto run and releases PTT), Band, Exit and Save & Exit. Key the radio with its own PTT to transmit; Auto keys it automatically, as on the radio.

Power Also on Pi & remotes(back to tree)

Starts the transmit power-amplifier calibration routine. Mustang 2 From V1.0.30 the same screen opens on the Pi and the remotes, with the step list (✓ done, ▶ current), Attenuation, measured and target power, the Psat / k / Gain table and buttons for Record (Select), Atten, Power, Incr, Units W/dBm, PA 20/100W, Next step, Reset, Band, Exit and Save & Exit. V1.0.30 also fixes the radio’s own “Transmit:” line, which always read Off.

Diagnostics

I2C BIT test Also on Pi & remotes(back to tree)

Runs a built-in-test screen checking the I2C-connected hardware: PASS or FAIL for the front panel, BPF, RF, RF SI5351 and K9HZ LPF boards. In Mustang 2 the results screen also opens on the Pi and the remotes, with a Home button to leave it.

Restore receive EQ Greyed out on Pi & remotes(back to tree)

Resets all receive equalizer bands back to their flat/default values. Greyed out on the Pi and remotes for now; use the front panel.

Buffer print Greyed out on Pi & remotes(back to tree)

Prints diagnostic buffer contents, for debugging. Greyed out on the Pi and remotes for now; use the front panel.

Sample Rate

192 ksps(back to tree)

Runs the radio's ADC/DSP chain at 192,000 samples per second.

176.4 ksps(back to tree)

Runs the radio's ADC/DSP chain at 176,400 samples per second.

Network Pi screen only

Wi-Fi page(back to tree)

Menu > Network on the Pi’s touch screen opens a full-screen Wi-Fi page: the current network (SSID), 2.4 or 5 GHz, signal and IP address; a list of the networks the Pi can see (signal, band, secured/open, connected/saved); and Rescan, Connect, Forget and Close. Picking a secured network that isn’t saved yet opens a password box with an on-screen keyboard (Shift, ?123 for numbers and symbols, Show/Hide). It isn’t on the web remotes, because switching networks from a browser on the current one would cut it off. After a switch the Pi has a new address, shown on the page. More in Chapter 2.

Settings Pane

The normal on-screen status/readout box (Page 1), shown whenever CW Decode is off. A fixed top row, then a two-column grid, then two full-width bottom rows.

Top Row

Vol:(back to contents)

Shows whichever parameter the main Volume/adjust encoder currently controls - the label itself changes to match: Audio Volume (“Vol:”), AGC threshold (“AGC:” - not the AGC mode indicator on the right), Mic Gain (“Mic:”), or Sidetone Volume (“STn:”). Pi & remotes there, Vol: (audio volume) is shown in the Settings pane.

AGC:(back to contents)

Current AGC mode, shown as a single letter: 0 = Off, L = Long, S = Slow, M = Medium, F = Fast.

Column 1 (left)

Tune Inc:(back to contents)

The main tuning-knob step size in Hz (Menu > RF Options-adjacent “TI” increment).

RX Atten:(back to contents)

Receive attenuation (dB) ahead of the receiver, per band - same value as Menu > RF Options > RX Attenuation.

TX Atten:(back to contents)

Transmit attenuation actually in effect right now: the CW-mode attenuation value while receiving CW, 0 while in SSB/digital receive (digital transmit uses the SSB path), otherwise the previous reading is held.

DSP Gain:(back to contents)

A global receive DSP gain trim (dB) applied across all bands. Pi & remotes shown as DSP: on the readout line above the spectrum.

Antenna:(back to contents)

Selected antenna port (0-3) for the current band - same value as Menu > RF Options > Antenna.

Rate:(back to contents)

Current ADC/DSP sample rate (192 ksps or 176.4 ksps) - same value as Menu > Sample Rate.

Temp(F):(back to contents)

Teensy internal CPU temperature in °F, sampled every 5 seconds.

Column 2 (right)

FT Inc:(back to contents)

The Fine Tune knob's step size in Hz.

AutoNotch:(back to contents)

On/Off - whether the automatic notch filter (removes steady tones/heterodynes from receive audio) is active.

Noise:(back to contents)

Active noise-reduction mode: Off, Kim, Spec (Spectral), or LMS - same setting as Menu > Audio Options.

Voltage:(back to contents)

Always reads “N/A” - there is currently no supply-voltage sensing hardware on this board.

Zoom:(back to contents)

Spectrum/waterfall zoom factor (1x-16x).

Zoom narrows the spectrum/waterfall display around the tuned frequency: at each step up, the displayed bandwidth is cut in half. The rule is simply displayed bandwidth = sample rate ÷ zoom factor, centered on the tuned frequency (half above, half below).

Zoom	Bandwidth @ 192 ksps	Bandwidth @ 176.4 ksps
1x	192 kHz (±96 kHz)	176.4 kHz (±88.2 kHz)
2x	96 kHz (±48 kHz)	88.2 kHz (±44.1 kHz)
4x	48 kHz (±24 kHz)	44.1 kHz (±22.05 kHz)
8x	24 kHz (±12 kHz)	22.05 kHz (±11.025 kHz)
16x	12 kHz (±6 kHz)	11.025 kHz (±5.5125 kHz)

Load:(back to contents)

DSP loop CPU load, as a percentage, sampled once per second. Mustang 2 From V1.0.27 it measures only the signal processing; earlier versions also counted time spent waiting for the audio output, which made it read 60–79% after power-up and drop to about 20% once DATA mode restarted the audio.

Bottom Row

VERSION(back to contents)

The firmware version string, right-aligned in red at the bottom of the pane.

CW Settings Pane

Replaces the Settings pane above, in the exact same screen area, whenever CW Decode is turned on (Menu > CW Options / the Decode button). Several rows are read-only reflections of CW Options menu settings; the last four (Dit(ms):, Upd Age:, AvgD/D:, Coeff:) are hardware-testing diagnostics for the CW speed tracker, not user controls.

Mustang 2 From V1.0.34 the Pi and the web and phone remotes switch to this page at the same time as the radio (without Vol: and AGC:, which are on their readout line already), and the decoded text shows on a line under the waterfall on the Pi and in a strip along the bottom of the waterfall on the remotes — with “CW” in green once the decoder locks and the decoded WPM. The radio only keeps its last 15 characters; the Pi keeps a much longer line.

Top Row

Vol:(back to contents)

Same multi-function display as the Settings pane (Vol/AGC threshold/Mic/Sidetone Volume). Pi & remotes not shown on this page there.

AGC:(back to contents)

Same AGC mode indicator as the Settings pane. Pi & remotes not shown on this page there.

Left Column (top to bottom)

Decoder:(back to contents)

On/Off, with a small colored box next to it: green once the decoder has confidently locked onto a signal, red while on but not locked, hidden while Off.

AT Grace:(back to contents)

The configured CW auto-tune grace period in seconds - a live, read-only reflection of Menu > CW Options > “AT Grace (s)”, not a separate control.

Mode:(back to contents)

Auto or Manual - a live, read-only reflection of Menu > CW Options > “CW Manual Mode”: Auto lets CW auto-tune track the signal on its own, Manual hands tuning fully to the operator.

Key Type:(back to contents)

Straight Key, or “Keyer (N WPM)” showing the current keyer speed - a live, read-only reflection of Menu > CW Options > Straight key/Keyer.

Dit(ms):(back to contents)

Diagnostic: the raw dit length (ms) currently driving CW decode timing - the number to watch directly (independent of the 1200/x WPM conversion) when investigating whether the speed tracker is responding.

Upd Age:(back to contents)

Diagnostic: seconds since the CW speed tracker last updated its dit-length estimate. Should stay at or below about 5s while receiving continuously; climbs without bound while CW Manual Mode has the tracker paused.

Right Column (top to bottom)

WPM:(back to contents)

Live decoded CW speed in words per minute. Reads “--” until the decoder has locked onto a signal and gathered enough timing data to estimate a speed.

SNR:(back to contents)

Approximate signal-to-noise ratio (dB) of the CW tone being decoded. Reads “--” until locked, same gating as WPM:.

AvgD/D:(back to contents)

Diagnostic: smoothed, exponentially-averaged dit and dah lengths (ms), shown side by side as “dit/dah” - an alternate speed estimate that reacts faster to a genuine speed change than Dit(ms):/WPM:, for comparing against them.

Coeff:(back to contents)

Diagnostic: the raw combinedCoeff correlation value driving CW decode/lock (10 × average correlation × 100 × Goertzel magnitude). Compare by eye against the two thresholds used internally: 50 (must be cleared to feed the character decoder at all) and 120 (must be cleared for the Decoder: lock indicator and WPM:/SNR: to trust the signal).

Bottom Rows

Temp(F):(back to contents)

Same CPU temperature readout as the Settings pane.

Load:(back to contents)

Same CPU/DSP load readout as the Settings pane.

VERSION(back to contents)

Same firmware version string as the Settings pane.

Chapter 2 · The Pi 5

Overview

A Raspberry Pi 5 sits alongside the Teensy 4.1, driving a 7″ Raspberry Pi Touch Display 2 (720×1280, rotated to landscape). The Teensy keeps doing everything it has always done – all the real-time audio, DSP and RF control; the Pi only draws the screen and handles the mouse (and touch). The two talk over a serial link called PiLink: the Teensy sends frequency, mode, settings, S-meter and spectrum data down to the Pi, and the Pi sends clicks and wheel turns back up as ordinary front-panel button presses and knob turns – nothing it does is a capability the T41 doesn’t already have (Chapter 1). The Pi is an add-on, not a dependency: the physical front panel stays wired straight to the Teensy, and if the Pi is unplugged or crashes, the radio keeps working exactly as it does now.

The Touch Display screen

A full mirror of the Teensy’s own display, scaled up and in the same layout: VFO, frequency/band/mode, spectrum and waterfall (with the Teensy’s own colors and frequency ruler), S-meter, REC/XMT, SWR/power, audio spectrum, the Settings pane and a clock badge. When the front panel switches to the secondary (“Toggle Layout”/Spare) home screen, the Pi follows. A readout strip above the spectrum adds Vol, AGC, Scale, Floor, Zoom, TI (tune increment), FT (fine-tune increment) and Noise at a glance, and the Pi’s own network address sits next to the clock, with Local Time and UTC readouts beside it. A blue highlight over the spectrum marks the receive passband, just like the tuning bar on the Teensy’s own screen.

Toolbar & Menu

In place of the radio’s own Menu button, the Pi (and both remotes in Chapters 3–4) reaches every control through a mouse-driven toolbar, built straight from the firmware’s own tables. Every pick sends the radio exactly the same button press or knob turn the front panel would; with firmware V1.0.28 or later a dropdown pick jumps straight to the item instead of stepping through every entry on the way.

Button	What it does
Menu	RF Options, EEPROM, Calibration, Diagnostics and Sample Rate, plus Network on the Pi screen.
Display	The Display menu, grouped: Spectrum floor ▸ Auto / Manual / Spectrum floor · Spectrum scale, smoothing, decay, trace smoothing · Spectrum shadow ▸ On / Off · Spectrum fill ▸ On / Off · Brightness ▸ 25–100% · Freq Font ▸ · PI Spectrum ▸ PI Spectrum Fill, PI Waterfall, PI Waterfall Speed.
Audio	The Audio Options menu, item for item.
Mic	The Microphone menu.
CW	The CW Options menu.
Vol	A plain button: sets the radio’s Volume knob back to audio volume (from AGC / Mic / Sidetone if needed) and points the mouse wheel and arrow keys at it. Mic gain, sidetone and AGC are under Mic, CW and Audio.
Band, Mode, Demod, Course, Fine, Zoom, Filter, Noise, Decode, Home	The same as the matching front-panel buttons. Filter picks Lo Cut or Hi Cut and points the wheel at it.
CW Key Pi screen only	On the Pi’s third toolbar row, next to Wheel, and only in CW mode. Hold it to key down (it turns red and reads “CW KEY”), let go for key up, like a straight key in the KEY jack. Needs firmware V1.0.35. Not on the web or phone remote.

• Current choice highlighted: on any menu with two or more choices the current (or last-picked) one is marked — bold green with a dot on the Pi, a green check on the web. It follows the radio, so front-panel changes show too.
• The mouse wheel works the knobs it adjusts a Menu setting while the red parameter box is showing (with a “Select >” to confirm, like the real SELECT button), or Volume/AGC/Mic/Sidetone or the filter after picking them from Vol or Filter. A “Wheel:” indicator shows what the wheel controls; click it to hand the wheel back to tuning.
• Readout line above the spectrum: AGC, DSP (RX DSP gain), Scale, Floor, Zoom, CT (course tune step), FT (fine tune step), Noise. Vol (audio volume) is in the Settings pane.
• Pi-only settings (Brightness, Freq Font, PI Spectrum Fill, PI Waterfall, PI Waterfall Speed) are shared by the Pi and every open remote, and the Pi remembers them across restarts.
• Desktop icons on the Pi’s own screen start the radio app and shut the Pi down cleanly, with a confirmation first.

Calibration & test screens

Every Menu > Calibration item (S meter level, Frequency, Receive IQ, Transmit IQ, Power), the Audio Equalizer and Menu > Diagnostics > I2C BIT test open full-screen on the Pi (and both remotes) – see each one’s own entry in Chapter 1’s Calibration section for exactly what it offers. A few Menu items without a Pi screen yet (Diagnostics > Restore receive EQ/Buffer print, EEPROM > Print data to Serial) are greyed out for now; they still work from the radio’s own front panel. Front Panel Test (Menu > Front Panel Test, or the Diagnostics menu) lights up each of the 22 front-panel buttons on the Pi and both remotes as it’s pressed on the radio, and shows each of the 4 encoders’ (Volume, Filter, Center tune, Fine tune) running turn count and direction.

CW operation

With Decode on, the decoded text runs along a line under the waterfall – green “CW” once locked, with the decoded WPM – and the Settings pane switches to the radio’s own CW settings page (Chapter 1). A CW Key button on the Pi’s third toolbar row, shown only in CW mode, acts as a straight key in the KEY jack: hold it to key down, let go for key up. While held, the Pi re-sends key-down every 300 ms and lets go after 30 s or if the mode leaves CW; the radio releases the key itself if the Pi goes quiet for 1 s. This button is Pi-screen only – neither web remote has it.

Digital (FT8/FT4) operation

Reached from Menu, the Pi decodes and transmits FT8/FT4 itself – no PC or WSJT-X needed. The screen has band buttons, a UTC clock with a period-position bar and sync check, a colour-coded decode list (tap a line to answer it) with CQ-tries/Answer-tries limits and a Dist/Brg (distance and bearing) column once Setup has your grid set, a QSO panel (CQ, Enable TX, Halt, Auto, Tune, Log QSO), an SWR/power meter, and a waterfall you can tap to move your TX offset. Auto-sequencing works like WSJT-X and logs completed QSOs to ~/mustang_digital.adi (ADIF); a View Log button opens a smaller read-only window listing what’s already logged (newest first: date, UTC time, call, grid, band, mode, RST sent/rcvd), with Name/Country columns, a Lookup QRZ backfill button, Refresh, CSV/PDF/ADIF export, and checkbox-select + Delete for removing a bad QSO. Needs the Serial + MIDI + Audio firmware build and the Teensy USB cable into the Pi, since it switches DATA mode, frequency and PTT over the Teensy’s own CAT port. Both web remotes have the identical screen, reflowed to stack vertically on the phone page (Chapters 3–4), with full transmit control – the Pi’s screen and any number of browsers all drive and watch the same QSO at once, with no lock between them.

Pi-only settings

Menu > Settings (Global Settings) holds app-wide values that live on the Pi, not the radio: Call Sign (the name badge on the Pi’s own screen), Local Time Zone (quick-pick US zones or any IANA zone, used only for the Local Time readout, independent of the Pi OS’s own system clock so FT8 timing can stay on UTC), and Pi Display Timeout (blanks the screen Off/1–30 min after no mouse/touch activity; any movement brings it right back). Saved to the Pi and effective immediately. Menu > Network, Pi-screen only, is covered in Chapter 1.

What’s different about the Pi’s own screen

• Three toolbar rows (the web remote fits the same controls into two), with REC and SWR at the right edge.
• CW Key and Menu > Network are Pi-screen only – neither appears on a web or phone browser.
• The hidden Pi OS top panel (for restarting the app or shutting down) opens by hovering the very top edge of the fullscreen touchscreen for 3 s, to keep a stray touch from popping it open by accident.

Chapter 3 · Web Remote

Connecting

The web remote is served directly by the Pi 5 – no separate web server, app or account needed. On any computer, tablet or phone on the same home network as the radio, open a browser and go to:

http://<pi-hostname>:8765/

Replace <pi-hostname> with the Pi’s network name (for example mustang.local) or its IP address. The page asks for a passkey before it connects – set in the Pi’s config.py, separate from the home network’s own Wi-Fi password. Once logged in, the page starts mirroring the radio immediately. Any modern desktop browser works – Chrome, Firefox, Edge and Safari have all been used with it – with no plugins, extensions or app install needed. On a phone, use Chapter 4’s page instead; the two share the same URL and passkey, just /mobile on the end.

Layout & panes

The page mirrors the same panes as the radio’s own screen and the Pi’s Touch Display (Chapter 2), arranged the same way: VFO/frequency readout with band/mode and REC/XMT across the top, the toolbar just under it, the S-meter at 20 Hz, the spectrum and waterfall (2D or 3D, picked under Display > PI Spectrum) with the blue passband highlight and a red-marked frequency ruler, the audio spectrum with passband and CW filter markers, the readout strip (AGC, DSP, Scale, Floor, Zoom, CT, FT, Noise), SWR/PWR, and the Settings pane (switching to the CW settings page when Decode is on).

Controls: toolbar & Menu

Every toolbar control works exactly as described for the Pi in Chapter 2 – the same Menu, Display, Audio, Mic, CW, Vol, Band/Mode/Demod/Course/Fine/Zoom/Filter/Noise/Decode/Home, and the same Calibration and test screens, with one exception: CW Key and Menu > Network are Pi-screen only and don’t appear here. What’s different on the web page is how you drive it:

• Click instead of tap/mouse-on-touchscreen; the cascading Menu opens and flies out the same way.
• A “Wheel:” status pill shows what the mouse wheel currently controls — Tune only, Volume, or Filter. Clicking Vol, or picking Hi Cut/Lo Cut from Filter, claims the wheel (and the arrow keys) for that knob; click the pill to release it back to tuning-only.
• Mute sits with the other toolbar controls and turns red while muted (see Audio & Mute below).

Tuning

Three ways to move the VFO (or adjust Filter/Volume) from this page:

• Mouse wheel over the frequency readout or the spectrum turns the main tuning knob; hold Shift while scrolling for fine tuning. This works independently of whatever the wheel is currently claimed for (Volume or Filter, via the “Wheel:” pill above) — the knobs don’t interfere with each other.
• A USB rotary encoder, configured (in its own software or a keyboard-emulation mode) to send arrow or page keys, drives the VFO the same way regardless of where the mouse pointer is.
• The virtual rotary dial – a draggable dial that floats over the page without blocking it, for Tune/Fine-tune, Filter, and Volume. “Freq Dial” opens a Course/Fine dial that sends the same tune/fine-tune clicks the mouse wheel does, driven by drag angle; “Filter Dial” and “Vol Dial” work the same way for the filter edge and the volume knob. Each dial’s center shows its live value and can be tapped to close it or held to drag it anywhere on screen. Menu > Rotary Dial sets each dial’s size (Small/Medium/Large) and on-screen position, saved per-browser; a Layout choice there picks Both (every dial independent, the default) or Single (one shared dial that Freq Dial/Filter Dial/Vol Dial retarget instead of each opening its own), with automatic collision-avoidance so open dials don’t overlap.

Keyboard: Up/Down tune (Shift = fine). Left/Right adjust Filter Lo/Hi Cut or Volume after picking it; after Vol all four arrows change the volume. In a Menu value box every arrow changes the value; on the Equalizer screen Left/Right pick the band and Up/Down its level. A trackpad scroll moves one step per short swipe and ignores sideways movement.

Audio & Mute

When the Teensy’s USB audio is wired to the Pi, the web remote streams live receive audio to every logged-in browser – uncompressed, over the same connection as everything else, with no codec or plugin to install. Playback starts automatically once logged in (browsers require a user click before audio can start, which logging in already provides). The Mute button in the toolbar turns red while muted and is local to your browser tab only: it doesn’t stop the Pi from sending audio, and has no effect on the radio, the Pi’s own speaker, or any other viewer’s audio. If nothing is heard: the Teensy’s USB audio cable to the Pi may be unplugged, or the Pi’s audio software isn’t installed – either way nothing else on the page is affected.

Security

LAN onlyThe web remote has no encryption — it’s plain ws://, not wss://. Don’t forward port 8765 through your router to reach it from outside your home network. The passkey stops casual access on the LAN; it isn’t a substitute for TLS against a hostile network.

Reaching the radio from outside the home would need real encryption and a stronger passkey, or a VPN back into the home network – never a plain port-forward. See the Secondary CPU project page for this as a future item.

Troubleshooting

Page won’t load

Confirm the computer is on the same network as the Pi, and that radio_ui.py is running on the Pi (it also runs the web server). Double-check the hostname/IP and that :8765 is included in the URL.

A recent change doesn’t seem to show up

Browsers can cache the page. Do a hard refresh instead of an ordinary reload: Ctrl+Shift+R (Windows/Linux) or Cmd+Shift+R (Mac), or open the browser’s developer tools and enable “Disable cache” while the page is open.

Login asks again every time

Normal – the passkey isn’t stored between sessions on purpose.

Menu pick jumps back to Home

Fixed in firmware V1.0.15, which sends the Menu’s real position to the Pi. Check the Settings pane’s firmware version; reflash the Teensy if it’s older.

No audio

See Audio & Mute above – usually a disconnected USB audio cable or missing Pi-side audio software, not a browser problem.

CW page shows “--”

WPM and SNR fill in once the decoder locks, and Dit, AvgD/D, Upd Age and Coeff only while in CW receive with Decode on – the same as on the radio.

Spectrum/waterfall frozen

Check the Pi’s own screen first – if it’s frozen too, the issue is the PiLink link or radio_ui.py itself, not the browser page.

Known limits

• State of Health isn’t on the web page yet.
• A few Menu items are greyed out until they get their own remote screen (see Chapter 1).
• No PTT time-out or screen/browser lock – two people driving it at once (or the Pi’s own screen and a browser) can conflict. This includes the Digital/FT8 screen, which deliberately has full transmit control from a browser with no lock against the Pi’s own screen.
• No general voice/CW transmitting from a browser – the on-screen CW Key is Pi-screen only. The Digital (FT8/FT4) screen is the one exception, with full transmit control from either web remote.
• LAN only, as above – no remote access from outside the home network.

Chapter 4 · Mobile Remote

Connecting

The phone page, Mustang Mobile, is the same web remote server as Chapter 3, at a different path:

http://<pi-hostname>:8765/mobile

Same host, same passkey as the desktop page. It’s built for a phone or small tablet screen; a laptop or desktop browser should use /remote instead.

Layout differences

The page mirrors the same panes described in Chapter 3 – frequency, toolbar, S-meter, spectrum/waterfall with the readout strip, audio spectrum, Settings pane – reflowed for a narrow screen:

• The toolbar becomes a six-column grid of buttons (four columns on some screens) instead of the desktop’s two dropdown rows.
• Dropdowns open as the phone’s own native pickers (an iOS wheel picker, for example) instead of an in-page popup list – Band, Mode, Demod, Course Inc and the rest all work this way.
• The Menu’s cascading flyouts open with a tap, the same categories and options as Chapter 1; the Display menu specifically opens as an accordion (its sub-groups expand inline) so four levels of nesting still fit a phone screen.
• The on-screen version label reads Mustang Mobile and its own version number, separate from the desktop page’s.

Touch sliders

In place of the desktop page’s mouse wheel and rotary dial, four touch sliders sit at the bottom of the screen: Tune, Fine Tune, Volume and Filter. Drag one away from the center to turn that knob – further for faster – and it springs back to the center when you let go. The Volume slider’s label shows which of Vol/AGC/Mic/Sidetone it will change, and the Filter slider’s label shows Hi Cut, Lo Cut, or “Menu” while a Menu setting box is open. Tuning with these always works independently of whatever the toolbar’s Vol/Filter picks have claimed, the same non-interference rule as the desktop wheel in Chapter 3.

Menu & toolbar

Every control behaves exactly as described for the Pi in Chapter 2 and the web remote in Chapter 3 – same Menu categories, same Calibration/test screens, same Mute button (red while muted, local to this browser only) – just reached through the six-column grid and native pickers above instead of dropdowns. CW Key and Menu > Network remain Pi-screen only and don’t appear here either.

CW and Digital (FT8/FT4) on mobile

CW decode and the CW settings page work the same as described in Chapter 2 and Chapter 1 (without the Pi-only on-screen CW Key). The Digital (FT8/FT4) screen from Chapter 2 is identical here too, with full transmit control, reflowed to stack its band buttons, decode list, QSO panel and waterfall vertically for a phone screen instead of the Pi’s/desktop’s side-by-side layout.

Differences from the desktop web remote

• No virtual rotary dial (Chapter 3) – the touch sliders above do that job on a phone.
• No USB rotary encoder or keyboard shortcuts – there’s no keyboard to wire one to.
• No CW Key or Menu > Network, same as the desktop page (both remain Pi-screen only).
• Everything else – Security, Troubleshooting and Known limits from Chapter 3 – applies here unchanged: LAN only, no encryption, same passkey, same lack of a PTT time-out or screen lock.

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Mustang & Mustang 2 firmware · T41-EP SDT

Firmware

Mustang is my build of the Phoenix T41-EP SDT firmware, with changes to the display, spectrum and CW decoding. Mustang 2 adds PiLink, the link to the Raspberry Pi 5 Secondary CPU, which brings the Pi Touch Display and remote access from a browser or phone. Download the current releases below, or read what changed in each version.

Firmware Downloads

Flashing the .hex

Building from source

Release Notes

Newest first. Versions not listed had no user-visible changes.

Mustang V1.0.39

Mustang 2 V1.0.49

Teensy firmware changes only; each one needs a reflash. Changes that only touch the Pi are under Remote Access and on the Secondary CPU page.

Remote Access

The browser pages run on the Pi, so these updates need no reflash: copy the new files to the Pi and hard-refresh the browser.

/remote — web (laptop / desktop) V1.0.34

/mobile — phone (Mustang Mobile) V1.0.55

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Gallery

Photos

Build photos from my projects: the Chassis System, the BPF Toroid Retainers, the Display Shield and the Secondary CPU. Select a photo to open it full size.

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Hardware

Chassis System

Overview

I built this chassis system to solve a few problems I encountered. I have the metal case from Justin (AI6YM Store — T41-EP SDT), and I wanted an easier way to connect all the ribbon cables, power cables, RF cables, etc. Placing the PCBs in the case and then trying to connect everything was a nightmare, and having to pull the PCBs out for troubleshooting was cumbersome.

Once the PCBs and all the cabling are attached, removing or inserting the chassis requires (in my case) connecting or disconnecting the main power from the power distribution, the RF cables from the 20 W PA, the USB connection on the Teensy, the case fan from the power distribution, and the display and front panel cables — a total of 6 connections. Once that’s done, I can place the chassis into or remove it from the case. It only takes a minute and it’s ready to go. With the handles in place, it still has about 10 mm of clearance when the top panel is on.

This also makes troubleshooting much easier: I can place the chassis outside the case, connect the power, display, front panel, etc., and have access to all the PCBs at once, from all sides.

PCB Mount

The PCB mount can be used with or without the main chassis base plate.

Chassis Base System

The chassis base plate comes in two versions: one with a side extension that you can attach a power distribution board (or anything else) to, and one without it, for cases that are too narrow for the extension.

The PCB mounts and handles attach to the base plate with 3 mm bolts and washers. The handles are optional, but they make it much easier to lift the chassis system in and out of the case.

Use longer bolts in the outside slots — long enough to pass through the handles or PCB mounts and reach through the case. On the bottom, the outside slots are recessed so the washers and nuts sit in place without raising the chassis base system off the case once it’s installed.

In the “radio turned over” photo, the radio is upside down so I can adjust the outside bolts to line them up with the holes in the case. I used wing nuts on the bottom to make the chassis base system easier to remove.

Chassis Handles

The chassis handles make it much easier to move the system in and out of the case. You can also use them to tie-wrap loose cables and wiring.

Chassis Handle — Flat Plate (V1)

An updated handle with a solid flat plate across the middle, built stronger than the original handle so it can carry some weight. You can mount just about anything to it — in the photo it's holding the Raspberry Pi 5's power supply converter board (with its own small cooling fan), stuck down with Velcro rather than bolted. Same slotted mounting rails on each end as the original handle, so it bolts to the base plate the same way.

Parts list

I printed the parts in PETG, but I’m sure PLA will also work, as the radio doesn’t get that hot. If the parts are too long for your printer, use your slicer to cut them with connectors.

Printed parts

PETG (PLA should also work), 0.4 mm nozzle, basic filament settings — nothing special

Threaded inserts

M3 × 4 × 5 metric threaded inserts

PCB mounts

3 mm × 8 mm bolts with washers

Chassis to case

3 mm × 16 mm bolts with washers and wing nuts, in the four corners

Downloads

3D-printable files for the chassis parts. Print settings and hardware are in the Parts list above.

• Chassis HandleSTL · 936 KB · 116 × 120 × 10 mm
• Chassis Handle — Flat Plate (V1)3MF · 240 KB
• Chassis Base Plate, with side extensionSTL · 1.0 MB · 333.5 × 152 × 6 mm
• Chassis Base Plate, without side extensionSTL · 977 KB · 333.5 × 117 × 6 mm
• PCB MountSTL · 1.6 MB · 35 × 115 × 13 mm

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Hardware · 3D printed

BPF Toroid Retainers

A two-piece 3D-printed retainer, a bottom tray and a top tray, for the toroids on the band-pass filter (BPF) board.

Overview

I wanted to make sure that when working in the radio I didn’t bump or move the toroids, and also to have a way to re-tune or replace them.

Photos

Printing

I printed them in PETG, but PLA will also work. I used a 0.4 mm nozzle and standard printer settings.

Downloads

3D-printable files for the two trays. The top tray covers the 30–160 m toroids and the bottom tray the 6–20 m toroids.

• Bottom Tray — 6–20 m toroidsSTL · 640 KB · 106 × 34 × 15.3 mm
• Top Tray — 30–160 m toroidsSTL · 761 KB · 106 × 42 × 15.3 mm

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Hardware · 3D printed

Display Shield

A 3D-printed shield for the video display, covered in copper tape and grounded to the chassis.

Overview

This is a 3D-printed shield for the video display. I covered it with copper tape and grounded it to the chassis. This cut down on the noise considerably.

Photos

Mounting

The shield mounts on 3 mm × 20 mm bolts that come up through the case: nuts hold the display board, and the shield sits above it, held by another nut.

Hardware: 3 mm × 20 mm bolts, nuts and washers.

Downloads

3D-printable file for the shield. Cover it with copper tape and ground it to the chassis after printing.

• Display ShieldSTL · 646 KB · 188 × 110 × 15 mm

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Hardware · software · Mustang 2 V1.0.50 · as of 12 Oct 2026

Secondary CPU

A Raspberry Pi 5 added alongside the Teensy 4.1 to drive the graphics on a Raspberry Pi Touch Display 2, now with a mouse-driven toolbar and a browser remote, with live audio, on the home network.

Overview

This project is to add a secondary CPU, in this case a Raspberry Pi 5, to handle all the graphics to the Raspberry Pi Touch Display 2 screen. Future additions to this will be changing to dropdown menus using a mouse and also a remote control website.

Status

Running Still growing

The Pi 5 and Teensy are talking on the bench, running Mustang 2 V1.0.50. The Pi’s screen mirrors every pane of the Teensy’s own display, the toolbar dropdowns and mouse wheel control the radio, and a browser on the home network, including a phone, can see it, control it and play its receive audio. Every Calibration screen, the Audio Equalizer, the I2C BIT test and a Front Panel Test now work from the Pi and the remotes too, and in CW the decoded text and the CW settings page show there as well, with an on-screen CW Key to transmit. Digital modes are no longer a future item: the Pi decodes and transmits FT8/FT4 itself, no PC or WSJT-X needed, with full transmit control from either web remote too — see it running on 40 m below. Most recently: a Menu > Settings page, an FT8 log viewer, and the new Front Panel Test for the front-panel buttons and encoders.

How it works

The Teensy 4.1 keeps doing everything it does today: all the real-time audio, DSP and RF control. The Pi 5 only draws the screen and handles the mouse. The two boards talk over a simple serial (UART) link called PiLink: the Teensy sends frequency, mode, settings, S-meter and spectrum data down to the Pi, and the Pi sends clicks and wheel turns back up as ordinary front-panel button presses and knob turns.

The Pi is an add-on, not a dependency. The physical front panel (buttons, encoders, key, PTT) stays wired straight to the Teensy. If the Pi is unplugged or crashes, the radio keeps working exactly as it does now.

powerdata / video

What it does

On the Pi’s own screen

• A full mirror of the Teensy’s display in the same layout, scaled from 800×480 to 1280×720: VFO, frequency/band/mode, spectrum and waterfall (with the Teensy’s own colors and frequency ruler), S-meter, REC/XMT, SWR/power, audio spectrum, the Settings pane and the clock badge. When the front panel switches to the secondary (“Toggle Layout”) screen, the Pi follows.
• Toolbar dropdowns, each built from the real firmware tables: Menu (with cascading flyouts, like a desktop app), Vol, Band, Mode, Demod, Course Inc, Fine Inc, Zoom, BW, Noise, Decode and Home.
• The mouse wheel works the knobs. It adjusts a Menu setting while the red parameter box is showing (with a “Select >” to confirm, like the real SELECT button), or Volume/AGC/Mic/Sidetone or the filter after you pick them from the Vol or BW dropdown. A “Wheel:” indicator shows what the wheel controls; click it to hand the wheel back to tuning.
• Blue filter highlight on the spectrum showing the receive passband, like the Teensy’s own tuning bar.
• Desktop icons to start the radio app and to shut the Pi down cleanly (with a confirmation first).
• Calibration and test screens: every Menu > Calibration item (S meter level, Frequency, Receive IQ, Transmit IQ, Power), the Audio Equalizer and Menu > Diagnostics > I2C BIT test open on the Pi and the remotes. The few Menu items without a Pi screen yet are greyed out there; they still work from the front panel. See the Mustang Manual for which ones.
• CW: with Decode on, the decoded text runs along a line under the waterfall (green “CW” once locked, with the decoded WPM), and the Settings pane switches to the radio’s CW settings page, just like the T41. A CW Key button also appears on the third toolbar row in CW mode: hold it to key down, like a straight key in the KEY jack (needs firmware V1.0.35). While held, the Pi re-sends key-down every 300 ms and lets go after 30 s or if the mode leaves CW, and the radio releases the key itself if the Pi goes quiet for 1 s.
• Digital (FT8/FT4) screen, reached from Menu: the Pi decodes and transmits FT8/FT4 itself, with no PC or WSJT-X needed — band buttons, a colour-coded decode list with CQ-tries/Answer-tries limits and distance/bearing, a QSO panel (CQ, Enable TX, Auto, Tune, Log QSO), an SWR/power meter, a waterfall you can tap to set your TX offset, and a View Log button that opens a smaller read-only window over the screen listing what’s already in the FT8 log (newest first: date, UTC time, call, grid, band, mode, RST sent/rcvd). Needs the Serial + MIDI + Audio build and the Teensy USB cable into the Pi. See the Changelog for the full rundown.
• Menu > Settings (Global Settings): Call Sign, Local Time Zone and Pi Display Timeout (screen-blanking), with room for more; saved to the Pi and effective immediately.
• Pi-only extras: a readout strip above the spectrum (Vol, AGC, Scale, Floor, Zoom, TI, FT, Noise), the Pi’s network address next to the clock with Local Time and UTC readouts, Menu > Display > Brightness for the touchscreen, and PI Spectrum Fill on/off for the Pi and remotes.

From a browser on the home network

• Open http://<pi-hostname>:8765/ on any computer on the same network. The page mirrors the VFO, toolbar, band/mode, REC/XMT, S-meter, spectrum and waterfall, audio spectrum, Settings pane and the Menu parameter box, and sends exactly the same commands the Pi’s own screen does.
• Tune with the mouse wheel over the frequency or spectrum (hold Shift for fine tuning), or with a USB rotary encoder set up to send arrow or page keys.
• Live receive audio plays in the browser, with a Mute button for that browser only. It comes from the Teensy’s own USB audio, over a USB cable to the Pi.
• A phone page, Mustang Mobile, at http://<pi-hostname>:8765/mobile: the toolbar becomes a six-column grid of buttons that open as the phone’s own pickers, and four touch sliders at the bottom (Tune, Fine Tune, Volume and Filter) stand in for the mouse wheel. Drag a slider away from the center to turn that knob, further for faster; it springs back when you let go. The Volume and Filter labels show what they’re set to adjust (for example AGC, Lo Cut, or a Menu setting).
• It asks for a passkey, which you set in config.py. Change it from the default.

For how to connect, what every control does and troubleshooting, see the Remote Access guide.

LAN onlyThe web remote has no encryption. Don’t forward port 8765 through your router to reach it from outside your home network.

Hardware

Secondary CPU

Raspberry Pi 5, 2 GB

Display

Raspberry Pi Touch Display 2, 7″ (720 × 1280, portrait native, rotated to landscape), DSI, using the “Standard – Mini” Touch Display cable (22-way on the Pi 5, 15-way on the display)

Power

Geekworm RPI5-5V5A-PD (terminal-block version) fed from its own fused branch off the 12 V distribution block, 5 A ATO fuse. It does real USB-C PD, so the Pi 5 runs at full performance with its overvoltage protection intact. Mean Well SD-25A-5 / SD-15A-05 GPIO-powered alternates are in the Integration Procedure

Display power

The display’s own power cable: red to Pi pin 2 (5 V), black to Pi pin 6 (GND)

UART link

Pi pin 8 (GPIO14 TXD) → Teensy pin 0 (RX1); Pi pin 10 (GPIO15 RXD) → Teensy pin 1 (TX1); plus a GND wire between the boards

USB audio

A USB cable from the Teensy’s own USB port to a Pi 5 USB-A port, with the firmware built as “Serial + MIDI + Audio”. Check that the Teensy’s VUSB–VIN link is cut first, so the Pi can’t back-feed 5 V into the main board

Mouse

Any wired USB mouse; a USB rotary encoder is optional for the web remote

Cooling

Official Raspberry Pi 5 Active Cooler, fitted (12 Oct 2026)

CheckTeensy pins 0/1 are only free if your main board uses the Voltage reversal prevention power option. The alternate Shutdown routine activation option (ATtiny85) uses the same two pins, and every other Teensy hardware UART is already taken on this board.

Never tie the Pi’s 5 V to the Teensy board’s own 5 V regulator. The two share a ground only.

UART connections

Main board schematic

UART link

921,600 baud on the Teensy’s Serial1, with a 1 KB transmit buffer so a whole spectrum frame fits.

Teensy → Pi

Message	Rate	Carries
STATUS	10 Hz	Frequency, band, mode, TX/RX, power, filter and passband edges, keyer WPM, SAM offset, the visible spectrum span, the band’s legal limits and (V1.0.15) where the Menu is
SMETER	20 Hz	Signal level in 0.1 dB steps
SPECTRUM	~15 fps	512 bins, one byte each, scaled with the Teensy’s own spectrum scale and floor settings
AUDIO_SPECTRUM	~15 fps	The live audio-FFT bars
SETTINGS	2 Hz	Everything on the Settings pane, the firmware version, Decode on/off, which home layout is showing, and the spectrum scale, floor and fill settings
PARAMETER	10 Hz	The red “Label: value” box, only while a Menu setting is being adjusted
RXIQ_CAL	10 Hz	The Receive IQ calibration screen, while it’s open
BIT_RESULTS	2 Hz	I2C BIT test pass/fail per board, while that screen is open
EQUALIZER	10 Hz	The Audio Equalizer screen (V1.0.26)
TXIQ_CAL / FREQ_CAL / POWER_CAL	10 Hz on screen, 2 Hz off	The Transmit IQ, Frequency and Power calibration screens (V1.0.30)
WATERFALL	~15 fps	The radio’s own colour for every waterfall point, so the Pi’s waterfall matches the T41 (V1.0.32)
CW_DECODE	10 Hz decoding, 2 Hz off	Decoded CW text, WPM and the CW settings page values (V1.0.33 / V1.0.34)

Pi → Teensy

Message	Carries	Purpose
VIRTUAL_BUTTON	One button id	A click, fed into the same button queue as the front panel
VIRTUAL_ENCODER	Knob + direction	One click of the Filter, Volume, Tune or Fine-tune knob, exactly like turning the real encoder
VIRTUAL_BUTTON_REPEAT	Button id + count	Presses the same button several times in one go, so jumping several steps in a dropdown is near-instant
MENU_SELECT	Menu category + item	Jumps straight to a Menu item (V1.0.28)
HEARTBEAT	—	Lets the Teensy notice when the Pi goes away
VIRTUAL_KEY	Key down / key up	The Pi’s on-screen CW Key, handled like a straight key. Re-sent every 300 ms while held; the Teensy lets go after 1 s without one (V1.0.35)

Frame

[0x7E][0xA5][TYPE][LEN_LO][LEN_HI][payload...][CRC-8]

A bad CRC drops the frame and the receiver scans ahead for the next 0x7E 0xA5. The Teensy parses one byte at a time so it never holds up the main loop.

Software

Teensy: PiLink.h / PiLink.cpp in the Mustang 2 sketch, started from InitializePiLink() and polled every pass of the main loop.

Pi: Raspberry Pi OS (64-bit, with desktop) running radio_ui.py, a full-screen Tkinter app, with pilink_client.py handling the protocol web_relay.py serving the browser remote and audio_relay.py passing the receive audio to it. It starts at boot as a user systemd service, and the SD card runs read-only so the Pi survives the radio’s power being switched off abruptly.

Firmware changes need the Teensy reflashed; Pi-only changes just need the PiDisplay folder copied to the Pi and radio_ui.py restarted. The full wiring, OS setup and test checklist are in the Integration Procedure below.

Changelog

Mustang 2 firmware and Pi display, newest first. The version on the Teensy’s Settings pane is what’s actually running.

Mustang 2 V1.0.50, 12 Oct 2026 Current download

• Front Panel Test (Menu > Front Panel Test, or from the T41’s own Diagnostics menu/front panel): every one of the 22 front-panel buttons lights up on the Pi and both web remotes as it’s pressed on the radio, and the 4 encoders (Volume, Filter, Center tune, Fine tune) show their running turn count and direction — a quick way to check a front panel after reassembly without an oscilloscope.
• The other four Diagnostics board tests (BPF, LPF, RF, USB serial) are now no-ops on this firmware build: they briefly touched the BPF/LPF/RF board drivers, I2C reads and the SWR bridge in a way that reintroduced the USB-audio timing glitch this firmware exists to avoid, so they’ve been pulled rather than risk that regression. The new Front Panel Test is pure display with no hardware access, so it didn’t have that problem and could stay real.

Pi, 12 Oct 2026 Current

• Menu > Settings: a Global Settings window for app-wide values — Call Sign (the name badge on the Pi’s own screen), Local Time Zone (quick-pick US zones or type any IANA zone, used only for the Local Time readout below, independent of the Pi OS’s own system clock so FT8 timing can stay on UTC), and Pi Display Timeout (blanks the screen Off/1–30 min after no mouse/touch; any movement brings it right back). Saved to the Pi and effective immediately; room for more settings as the project grows.
• The bottom-of-screen status strip next to the IP address now also reads Local Time: HH:MM and UTC: HH:MM.
• View Log button on the Digital (FT8/FT4) screen — Pi touchscreen and both web remotes — opens a smaller read-only window listing what Log QSO (and auto-sequencing) have already written to the FT8 log (~/mustang_digital.adi, ADIF), newest first: Date, UTC time, Call, Grid, Band, Mode, RST sent/rcvd.
• Fixed: on the web remotes’ Digital screen, Setup had been landing next to the clock instead of next to Back — a CSS spacing rule meant for the pair of them was on the wrong one of the two.

Pi, 12 Oct 2026

• Digital (FT8/FT4) screen on both web remotes (/remote and /mobile), with full transmit control: a browser can call CQ, answer, and key the transmitter exactly as the Pi’s own screen can — same FT8/FT4 toggle, band buttons, clock, decode list, QSO panel and waterfall as the Pi’s screen below, reflowed to stack vertically on the phone page. The Pi’s screen and any number of browsers all drive and watch the same QSO at once; there is no lock between them, by the same design as every other control on these pages.
• The hidden Pi OS top panel (revealed by hovering the very top edge of the fullscreen touchscreen) now only opens after the pointer has stayed in that hot zone for 3 s, instead of instantly — a quick accidental touch no longer pops it open.
• Fixed: on firmware not yet reflashed to V1.0.49, the frequency/Band/Mode/Filter readout, the spectrum’s frequency ruler and filter-bandwidth highlight, and picking the right band/mode/demod from a dropdown had all gone dark/wrong, because the STATUS message grew by 2 fields in V1.0.49 and the Pi was rejecting the shorter pre-V1.0.49 frame outright. Both sizes are accepted now, so an updated Pi no longer has to wait on a reflash to work correctly.

V1.0.49

• I/Q transmit VU meter on the Pi, in the same spot used for the retired State of Health pane — two bars, I and Q, with the same green/yellow/red thresholds as the T41’s own bars. Needs this reflash; until then the pane stays hidden, same as if the mic were never keyed.

Pi, 11 Oct 2026

• CQ tries and Answer tries boxes on the Digital screen: how many times CQ repeats, or a QSO step repeats, before Auto gives up (0 = no limit; defaults 0 and 6).
• SWR / power meter added below the Digital screen’s button grid, so it’s visible without needing the radio’s own display while running FT8/FT4; text turns red while transmitting, like the main screen.
• Decode list gets a Dist Brg column: distance and bearing from your own grid to a CQ caller’s, once Setup has your grid set.

Pi, 11 Oct 2026

• Digital (FT8/FT4) screen, reached from Menu: the Pi decodes and transmits FT8/FT4 itself, no PC or WSJT-X needed, using the same free decoder library (ft8_lib) the sBitx uses. UTC clock with a period-position bar and a clock-sync check, band buttons, a colour-coded decode list (tap a line to answer it), a QSO panel with CQ/Enable TX/Halt/Auto/Tune/Log QSO, and a waterfall you can tap to move your TX offset. Auto-sequencing works like WSJT-X and logs completed QSOs to ~/mustang_digital.adi (ADIF).
• Needs the Serial + MIDI + Audio firmware build and the Teensy USB cable into the Pi (the same cable the web remote’s audio uses) — it switches DATA mode, frequency and PTT over the Teensy’s own CAT port.
• RTC: an Adafruit DS3231 real-time clock keeps the Pi’s time accurate away from the internet, which FT8 needs within about a second.
• See it running on 40 m below.

V1.0.39 – V1.0.41

• Board tests (BPF, LPF, RF, Front panel, Board test/USB serial) added under Menu > Diagnostics on the T41 itself, then mirrored on the Pi with the same rows, live readings and Row ▲/▼ / −/+ / Select / Exit controls.
• 4 M removed everywhere (no transmit hardware on this radio); Power calibration’s band table trimmed to 160M–6M so it fits the screen again.

V1.0.36 – V1.0.38

• Tune button (CW modes) on the Pi and both remotes for a steady carrier, up to 60 s. Power calibration target/Select-while-PTT fixes.
• Calibration > Experimental: T41EVE IQ calibration, and Experimental TX IQ working on single-VFO radios. Auto no longer looks stuck on GEN when it finishes.

V1.0.35

• On-screen CW Key on the Pi’s third toolbar row, shown only in CW mode: hold to key down (it turns red and reads “CW KEY”), let go for key up.

V1.0.29 – V1.0.34

• Calibration > Transmit IQ, Frequency, Power and S meter level on the Pi and both remotes, with Exit and (Transmit IQ) Stop.
• CW: decoded text under the waterfall and the radio’s CW settings page while Decode is on.
• Waterfall in the radio’s own colours; brighter 2D and 3D blues; the frequency readout no longer shows through full-screen pages.
• Powers up in DATA mode; the radio’s spectrum fill and PI Spectrum Fill both start off.

V1.0.26 – V1.0.28

• Audio Equalizer screen on the Pi and both remotes (Edit RX / Edit TX, Exit, Save & Exit); menu picks jump straight to the item; “Load:” reading fixed.
• New toolbar: Display, Audio, Mic and CW dropdowns; Vol is a button; three toolbar rows on the Pi with REC and SWR at the right edge; menus highlight the current choice.
• Smooth 3D waterfall with 2D / 3D and speed settings; Freq Font styles (Nixie, VFD, Dot Matrix); Pi settings remembered across restarts.
• Menu > Network on the Pi screen: change Wi-Fi networks, with an on-screen keyboard for the password.
• DSP: on the readout line, Vol: in the Settings pane, TI: renamed CT:; arrow-key control of tuning, Filter and Volume.

V1.0.25

• I2C BIT test screen on the Pi and both remotes; Menu items without a Pi/remote screen are greyed out there for now.

V1.0.23 – V1.0.24

• Receive IQ calibration screen on the Pi and both remotes, with full control; the Pi screen adds Stop and Exit.

V1.0.21 – V1.0.22

• Choppy audio fixed: the filled spectrum trace could stall the audio. New Menu > Display > Spectrum fill on/off on the radio, and a separate PI Spectrum Fill for the Pi and remotes.

V1.0.17 – V1.0.20

• New Menu > RF Options > RX DSP Gain; Scale: and Floor: readouts; readout strip moved above a shorter spectrum trace; Menu > Display > Brightness for the Pi touchscreen; SWR/PWR on both web remotes.

V1.0.16

• Jumping several steps in a dropdown (Zoom, Band, Mode and so on) is now near-instant.
• Mustang Mobile phone page at /mobile with Tune / Fine Tune / Volume / Filter touch sliders.

V1.0.15

• The Teensy now sends the Menu’s real position, so choosing a Menu item from the Pi or the browser always lands on the right setting instead of sometimes jumping back to Home (reflash needed).

V1.0.14

• Live receive audio in the browser remote, with a Mute button.
• Blue filter-bandwidth highlight on the spectrum, on the Pi and in the browser.
• Desktop icons to start the radio app and shut down the Pi.
• Browser remote control on the home network, with passkey, mouse-wheel tuning and USB rotary encoder support.
• Tune and Fine-tune knobs can now be turned from the Pi or the browser (reflash needed).
• Browser remote gains the audio spectrum, Settings pane and a real cascading Menu.
• New BW (filter) dropdown, and a “Wheel:” indicator that hands the wheel back to tuning.

V1.0.13

• Frequency ruler under the spectrum, with out-of-band ticks in red, like the Teensy’s own screen (reflash needed).

V1.0.12

• “Select >” button on the Menu parameter box to confirm a value.
• The Pi follows the Teensy’s secondary (“Toggle Layout”) home screen.

V1.0.11

• Fixed: Menu → Display spectrum scale and floor now change the Pi’s spectrum too.

V1.0.10

• Vol dropdown (Vol / AGC / Mic / Sidetone), with the mouse wheel adjusting whichever is selected.
• Toolbar rearranged into two rows.

V1.0.9

• Red “Label: value” box when adjusting a Menu setting, with the mouse wheel changing the value.

V1.0.8

• Band dropdown replaces BAND +/−, plus Mode, Demod, Noise, Course Inc, Fine Inc, Decode, Home and a two-level Menu, all built from the firmware’s own tables.
• Menu opens with cascading flyouts; larger touch targets.

V1.0.7

• Fixed: REC/XMT could show XMT while receiving.
• Spectrum fill and waterfall now use the Teensy’s own colors; Settings pane restyled to match.

V1.0.6

• Settings pane now shows everything the Teensy’s does; the desktop panel appears when the mouse touches the top edge.

V1.0.5

• Live audio-spectrum bars.

V1.0.3 – V1.0.4

• Fixed: spectrum was a flat line, then empty (bigger serial buffer).
• Waterfall now scrolls top to bottom like the Teensy’s.

V1.0.2 and earlier Baseline

• The original PiLink link, S-meter and SWR/power panes.

Future

Already done since this page first went up: the hardware checkout, dropdown menus with the mouse, sending settings back to the Teensy (through button presses and knob turns), the rest of the Home screen, band and mode names, real button ids, the browser remote on the home network and live audio to it, matching the firmware source to the Pi software, a self-contained Digital (FT8/FT4) screen on the Pi — no PC or WSJT-X needed, a Front Panel Test, and fitting the Pi 5 Active Cooler — see the Changelog above. Still to come:

1. Finish the browser remote Planned

   State of Health isn’t on the web page yet. The Digital (FT8/FT4) screen already gives the browser full transmit control (12 Oct 2026), deliberately without a PTT time-out or a lock against the Pi’s own screen — still worth adding, now for a real transmitting feature rather than a hypothetical one. Voice/CW transmit from the browser (beyond the on-screen CW Key, Pi-only) remains undone. Check the rules for remote operation of your station before relying on any of this away from the shack.

2. Port the remaining Menu screens Planned

   Diagnostics > Restore receive EQ and Buffer print, and EEPROM > Print data to Serial, are greyed out on the Pi and remotes until each gets its own screen. (The Calibration screens were done in V1.0.30.)

3. Remote access from outside the home Idea

   Only with encryption (TLS) and a stronger passkey, or through a VPN, never by simply forwarding the port.

4. Accurate time for FT8 Idea

   FT8 needs the clock within about a second. NTP works on the home network; for portable use, add the Pi 5’s RTC battery or a small GPS.

5. Saving Pi settings

   Menu > Settings (12 Oct 2026) gave the Pi its own small settings file (call sign, local time zone, display timeout), written on Save. Still open: the Pi’s SD card is read-only so an abrupt power-off can’t corrupt it, and these writes go around that — EEPROM → “Save data to storage” on the Teensy could instead tell the Pi to save, through a new commit-settings message and a read-only setup that can be briefly unlocked without a reboot.

6. Version check between the boards

   The Pi shows the firmware version, but nothing stops a mismatch. A short hello message with a protocol version would let the Pi warn clearly when its code doesn’t match the Teensy firmware.

7. Ethernet, if the UART runs out Option

   The link has grown to fourteen downlink messages. If it ever gets tight, the Teensy 4.1’s Ethernet header (PJRC Ethernet kit + QNEthernet) straight to the Pi’s Ethernet port is the upgrade path. It replaces the whole link, so it’s a project of its own.

8. RF noise check

   The Pi 5 and a second display are new noise sources right next to the receiver. Listen for birdies on every band with the Pi running, and plan for ferrites on the USB, DSI and power leads and a shield like the Display Shield.

9. Mounting in the case

   The Pi 5 Active Cooler is fitted and running (12 Oct 2026). Still to publish: the Pi mount and touchscreen adapter plate STLs here, once they’re fit-checked.

Downloads

• Integration ProcedurePDF · 131 KB · 9 pages · updated 1 Oct 2026 (V1.0.25)
• Wiring Diagram (goes with the Integration Procedure)PDF · 38 KB · 1 page · updated 25 Sep 2026
• FT8 / WSJT-X Integration (early plan; superseded by the built-in Digital screen, see Changelog)PDF · 89 KB · 4 pages
• UART Protocol DesignPDF · 64 KB · 3 pages · updated 4 Oct 2026 (V1.0.34)
• T41 Main Board Schematic V012.6PDF · 201 KB · A3
• Mustang 2 Changelog (full, all versions)PDF · 197 KB · 14 pages · 6 Oct 2026
• Detailed changelog: Teensy firmwarePDF · 123 KB · 8 pages · 6 Oct 2026
• Detailed changelog: Pi displayPDF · 195 KB · 12 pages · 6 Oct 2026
• Detailed changelog: web remote (/remote)PDF · 117 KB · 15 pages · 15 Oct 2026
• Detailed changelog: phone remote (/mobile)PDF · 113 KB · 13 pages · 15 Oct 2026

The Mustang 2 firmware .hex files and the full source ZIP are on the Firmware page.

← Home

User guide · Mustang 2 V1.0.50 · /remote V1.0.76 · /mobile V1.0.66 · as of 15 Oct 2026

Remote Access

How to reach the radio from a browser on the home network, log in, and drive it: what every control does, tuning with a mouse wheel or a USB rotary encoder, live audio and the Mute button, and what to try if something looks stuck.

Connecting

The web remote is served directly by the Raspberry Pi 5 — no separate web server, app or account needed. On any computer, tablet or phone connected to the same home network as the radio, open a browser and go to:

http://<pi-hostname>:8765/

Replace <pi-hostname> with the Pi’s network name (for example mustang.local) or its IP address. The page asks for a passkey before it connects — this is set in the Pi’s config.py and is separate from any home network Wi-Fi password. Once you’re logged in, the page starts mirroring the radio immediately.

On a phone: use the phone page, Mustang Mobile, at http://<pi-hostname>:8765/mobile. The toolbar becomes a six-column grid of buttons that open as the phone’s own pickers, the Menu flyouts open with a tap, and four touch sliders at the bottom replace the mouse wheel (see Tuning).

Browser support: any modern desktop or mobile browser works — Chrome, Firefox, Edge and Safari have all been used with it. No plugins, extensions or app install are needed.

Layout & panes

The page mirrors the same panes as the radio’s own screen and the Pi’s Touch Display, arranged the same way:

• VFO / frequency readout across the top, with band and mode next to it and REC/XMT showing which state the radio is in.
• Toolbar of dropdown controls just under the frequency (see below).
• S-meter, live at 20 Hz.
• Spectrum & waterfall: the live trace fills green through yellow to red by signal strength, the receive passband is highlighted in blue, and a frequency ruler runs underneath with out-of-band edges marked in red. The waterfall can be flat (2D) or a 3D view where each new line rolls back into the distance and strong signals stand up as ridges: pick it under Display > PI Spectrum > PI Waterfall, and set how fast it moves with PI Waterfall Speed.
• Audio spectrum: the live audio-FFT bars with the passband edges and CW filter markers.
• Readout strip just above the spectrum: AGC, DSP, Scale, Floor, Zoom, CT (course tune increment), FT (fine-tune increment) and Noise.
• SWR / PWR readout next to REC/XMT.
• Settings pane: RX/TX Atten, AutoNotch, Vol, Antenna, Rate, Temp, Load and Power, plus the firmware version. With CW Decode on it switches to the radio’s CW settings page, and the decoded text runs in a strip along the bottom of the waterfall. The audio spectrum pane shows the current Filter width.

Toolbar & Menu

Every toolbar dropdown drives the radio exactly as if you’d pressed the matching front-panel button or turned the matching knob — there’s no separate remote-only logic to learn.

• Display, Audio, Mic, CW — copies of the radio’s own Display, Audio Options, Microphone and CW Options menus, next to Menu.
• Vol — a button: click it and the mouse wheel and all four arrow keys change the volume.
• Filter — Hi Cut / Lo Cut; once picked, the mouse wheel and the Left/Right arrow keys move that edge.
• Band, Mode, Demod, Course Inc, Fine Inc, Zoom, Noise, Decode, Home — one click each, built from the firmware’s own tables so the choices always match what’s actually loaded on the radio.
• Menu — a cascading popup like a desktop app: click Menu, then a category, and its options fly out to the side. Picking a setting opens the same red “Label: value” box the radio’s own screen shows, with the mouse wheel changing the value and a “Select >” to confirm.
• Calibration and test screens — every Menu > Calibration item, the Audio Equalizer and Menu > Diagnostics > I2C BIT test open right in the page; arrow keys adjust the main values on the calibration screens. The few items that don’t have a remote screen yet are greyed out and can’t be picked for now; they still work from the radio’s front panel (the Mustang Manual marks which ones).
• Mute — sits with the other dropdowns and turns red while muted. It only silences audio in your own browser tab; it doesn’t touch the Pi’s own speaker, other people viewing the page, or what the radio is actually receiving.

A “Wheel:” status pill shows what the mouse wheel currently controls — Tune only, Volume, or Filter. Clicking Vol, or picking Hi Cut / Lo Cut from Filter, claims the wheel (and the arrow keys) for that knob; click the pill to release it back to tuning-only.

Tuning

Two ways to move the VFO from a browser:

• Mouse wheel over the frequency readout or the spectrum — turns the main tuning knob. Hold Shift while scrolling for fine tuning.
• A USB rotary encoder, configured (in its own software or a keyboard-emulation mode) to send arrow or page keys — drives the VFO the same way regardless of where the mouse pointer is.

On the phone page, use the four sliders at the bottom: Tune, Fine Tune, Volume and Filter. Drag one away from the center to turn that knob, further for faster; it springs back to the center when you let go. The Volume label shows which of Vol/AGC/Mic/Sidetone it will change, and the Filter label shows Hi Cut, Lo Cut, or “Menu” while a Menu setting box is open.

Tuning always works this way, independent of whatever the plain mouse wheel is currently claimed for (Volume or Filter) — the two knobs don’t interfere with each other.

Audio & Mute

When the Teensy’s USB audio is wired to the Pi, the web remote streams live receive audio to every logged-in browser — uncompressed, over the same connection as everything else, with no codec or plugin to install. Playback starts automatically once you’re logged in (browsers require a user click before audio can start, which logging in already provides).

The Mute button in the toolbar turns red while muted. It is local to your browser tab only: it doesn’t stop the Pi from sending audio, and has no effect on the radio, the Pi’s own speaker, or any other viewer’s audio.

If you don’t hear anything: the Teensy’s USB audio cable to the Pi may not be connected, or the Pi’s audio software isn’t installed. Either way, nothing else on the page is affected — video/telemetry keeps working normally.

Security

LAN onlyThe web remote has no encryption — it’s plain ws://, not wss://. Don’t forward port 8765 through your router to reach it from outside your home network. The passkey stops casual access on the LAN; it isn’t a substitute for TLS against a hostile network.

Reaching the radio from outside the home would need real encryption and a stronger passkey, or a VPN back into the home network — never a plain port-forward. This is tracked as a future item on the Secondary CPU page.

Troubleshooting

Page won’t load

Confirm the computer is on the same network as the Pi, and that radio_ui.py is running on the Pi (it also runs the web server). Double-check the hostname/IP and that :8765 is included in the URL.

A recent change doesn’t seem to show up

Browsers can cache the page. Do a hard refresh instead of an ordinary reload: Ctrl+Shift+R (Windows/Linux) or Cmd+Shift+R (Mac), or open the browser’s developer tools and enable “Disable cache” while the page is open.

Login asks again every time

Normal — the passkey isn’t stored between sessions on purpose.

Menu pick jumps back to Home

Fixed in V1.0.15, which sends the Menu’s real position to the Pi. Check that the Settings pane shows Mustang 2 V1.0.15 or later (currently V1.0.34); if not, reflash the Teensy.

No audio

See Audio & Mute — usually a disconnected USB audio cable or missing Pi-side audio software, not a browser problem.

CW page shows “--”

WPM and SNR fill in once the decoder locks, and Dit, AvgD/D, Upd Age and Coeff only while in CW receive with Decode on — the same as on the radio. If AT Grace, Mode and Key Type also show “--”, the radio needs firmware V1.0.34.

Spectrum/waterfall frozen

Check the Pi’s own screen first — if it’s frozen too, the issue is the PiLink link or radio_ui.py itself, not the browser page.

Known limits

• State of Health isn’t on the web page yet.
• A few Menu items are greyed out until they get their own remote screen (Diagnostics > Restore receive EQ, Buffer print; EEPROM > Print data to Serial).
• No PTT time-out or screen/browser lock yet — two people driving it (or the Pi’s own screen and a browser) at once can conflict. This now applies to the Digital/FT8 screen too, which deliberately has full transmit control from a browser (12 Oct 2026) with no lock against the Pi’s own screen.
• No general voice/CW transmitting from a browser: the on-screen CW Key (firmware V1.0.35) is on the Pi’s own screen only. The Digital (FT8/FT4) screen is the one exception — full transmit control from either web remote, added 12 Oct 2026.
• LAN only, as above — no remote access from outside the home network.

See the Secondary CPU project page for what’s planned next.

Web Remote Changelog

The desktop/laptop page (/remote), newest first. This page has no on-screen version label of its own — check Menu > About for its current version, which now reads Mustang Remote V1.0.76. Unless noted otherwise, every entry here needs only a re-sync of PiDisplay/ and a hard refresh of the browser — no Pi restart or Teensy reflash.

V1.0.76, 15 Oct 2026 Current

• The small version number in the corner of the Settings box is now this page’s own hardcoded version, not the T41’s live firmware version. It used to show the Teensy’s own version there, unlabeled — easy to mistake for the page’s own version, especially since the phone page dropped that same field back in September in favor of its own label. The T41’s firmware version is still available in Menu > About.

V1.0.75, 15 Oct 2026

• Touch +/− for Menu parameters. On a phone or tablet with no keyboard or mouse, a Menu setting like Spectrum scale could be opened (“Select >”) but never actually changed — the value itself only moved with the mouse wheel or arrow keys. New −/+ buttons sit right next to “Select >” and send the same adjustment, the same idea as the Equalizer screen’s existing Level −/+ buttons. Fixes every Menu parameter that uses this box, not just Spectrum scale.

V1.0.74, 15 Oct 2026

• Display dropdown cleaned up. Spectrum smoothing, decay, trace smoothing and shadow on/off removed — none of them are carried over PiLink to the Pi, so they only ever affected the T41’s own screen and did nothing here. Spectrum floor, Spectrum scale, Spectrum fill, Brightness, Freq Font and the PI Spectrum group remain, since those do reach the Pi or are Pi-specific already. The firmware items themselves are untouched and still reachable from the T41’s own front panel.

V1.0.73, 15 Oct 2026

• CT:/FT: now shows the tuning increment, not the frequency. The rotary dial’s center readout reads what Course Tune/Fine Tune is actually set to (“CT: 100 kHz”, “FT: 250 Hz”), pulled straight from the same Course Inc/Fine Inc selectors the toolbar uses, so it can’t drift out of sync no matter which control changed it. The live frequency keeps its own line just below.

V1.0.71 – V1.0.72, 15 Oct 2026

• Two fixes to the rotary dial added in V1.0.70: the CT/FT mode pills lived inside the tap-to-close center circle, so every tap on them closed the dial instead of switching mode — moved onto two full-size Course/Fine buttons below the dial instead. The center readout’s text also wrapped and lost its centering at small/medium dial sizes on a wide frequency string; split into two independently-centered lines that fixed it at every size.

V1.0.70, 15 Oct 2026

• Virtual rotary dial added for Tune/Fine-tune on this page. A new “Dial” toolbar button opens a draggable rotary dial that floats over the page (not a modal — the rest of the page stays usable). Dragging it sends the same tune/fine-tune clicks the mouse wheel already does, just driven by drag angle. A new Menu > Rotary Dial settings page picks its size (Small/Medium/Large) and on-screen position, saved per-browser since it’s a display preference, not a radio setting.

V1.0.69, 15 Oct 2026

• Log viewer: checkbox select + Delete, for removing a bad QSO. The digital (FT8/FT4) log table’s first column is now a checkbox per row, with a Delete button next to Lookup QRZ that removes every checked contact (after a confirmation) and refreshes the log on every connected screen, not just the one that pressed Delete.

V1.0.68, 14 Oct 2026

• New About entry under Menu, showing the T41’s live firmware version alongside the Pi’s and both web remotes’ own versions, plus a link to boblance.net for downloads.
• Digital (FT8/FT4) moved off the Menu dropdown and into the bottom of the Mode dropdown; the greyed-out, never-enabled Menu > Tune entry was removed (the Tune toolbar button is the only Tune control now).

V1.0.67, 14 Oct 2026

• The digital log viewer gained Name/Country columns, a Lookup QRZ button for backfilling older contacts, a Refresh button, and CSV/PDF/ADIF export links — matching the Pi’s own screen.

V1.0.61 – V1.0.66, 9–11 Oct 2026

• 4M removed from the Band dropdown and calibration tables (the T41 has no 4 m hardware); a new Tune toolbar button gives a steady carrier in CW modes for up to 60 s; the Receive/Transmit IQ calibration screens show their Auto status (running/done/stopped); Menu > Calibration gained an Experimental flyout for the six T41EVE IQ routines; the CW settings page dropped its now-redundant Vol:/AGC: fields.

V1.0.55 – V1.0.60, 4 Oct 2026

• Menu > Calibration’s S meter level, Frequency, Transmit IQ and Power screens enabled; the waterfall switched to the T41’s own live colors and got several brightness passes to match the Pi’s screen; CW receive with Decode on shows a scrolling decoded-text strip along the bottom of the waterfall, with WPM.

V1.0.45 – V1.0.54, 2–3 Oct 2026

• New Audio, Mic and CW toolbar dropdowns (copies of the T41’s own menus); Vol became a plain button pointing the mouse wheel/arrow keys at Volume; a trackpad bug that made Filter Hi/Lo Cut jump around was fixed; arrow keys were wired up to reach the Filter knob; the Nixie-tube frequency font was redrawn to look like real tubes; and the Menu/Display items started marking the current selection with a green check.

V1.0.37 – V1.0.44, 30 Sep – 2 Oct 2026

• A full-screen Receive IQ calibration screen was added, with Stop/Exit controls; the SWR/PWR readout and the missing “(USB)” demod suffix were fixed; the spectrum pane was shrunk and its readout strip moved above it; Menu > Display gained a 3D waterfall option with an adjustable speed, and was regrouped into sub-menus (Spectrum floor, scale, shadow, fill, Brightness, PI Spectrum) without changing any of the T41’s own menu indices.

V1.0.21 – V1.0.36, 26–30 Sep 2026

• A mis-clocked audio playback rate that caused choppy sound was tracked down and fixed; the readout strip above the spectrum grew Scale:, Floor: and RX DSP Gain entries; toolbar dropdowns stopped overwriting their own fixed labels with the current selection; S-meter clipping and frequency-ruler/waterfall layout bugs were fixed; the spectrum trace’s fill color was matched exactly to the waterfall’s own gradient; and a full-screen Audio Equalizer overlay and the Menu > Diagnostics > I2C BIT test screen were added.

V1.0.14 – V1.0.20, 25–26 Sep 2026 Baseline

• The original LAN-only browser remote: mouse-wheel/USB-encoder tuning, the live audio spectrum, a Settings pane, a cascading Menu, live RX audio with a local Mute button, and the blue filter-bandwidth highlight over the spectrum — gated by a passkey set in the Pi’s config.py. The phone-specific layout that grew alongside this page was split out into its own file, remote_mobile.html (see the Mobile Remote changelog below), once it became clear a media-query alone couldn’t reliably tell a phone from a laptop.

Full version-by-version detail: Detailed changelog: web remote (/remote) (PDF).

Mobile Remote Changelog

The phone/tablet page (/mobile, “Mustang Mobile”), newest first. This page carries its own on-screen version label, currently Mustang Mobile V1.0.66. Unless noted otherwise, every entry here needs only a re-sync of PiDisplay/ and a hard refresh of the phone’s browser — no Pi restart or Teensy reflash.

V1.0.66, 15 Oct 2026 Current

• Same fix as the desktop remote’s V1.0.75: −/+ buttons added next to “Select >” in the Menu parameter box, so a value like Spectrum scale can be changed by tapping instead of needing a mouse wheel or arrow keys.

V1.0.65, 15 Oct 2026

• Same Display-dropdown cleanup as the desktop remote’s V1.0.74: Spectrum smoothing, decay, trace smoothing and shadow on/off removed — no PiLink-transmitted equivalent, so they never did anything here.

V1.0.64, 15 Oct 2026

• Same log viewer checkbox select + Delete as the desktop remote’s V1.0.69, for removing a bad QSO from the digital (FT8/FT4) log.

V1.0.63, 14 Oct 2026

• New About entry under Menu, same as the desktop remote’s V1.0.68; Digital (FT8/FT4) moved into the Mode dropdown; the greyed-out Tune entry removed from Menu.

V1.0.61, 14 Oct 2026

• The digital log viewer gained Name/Country columns, a Lookup QRZ button, a Refresh button, and CSV/PDF/ADIF export links, matching the Pi’s own screen.

V1.0.55 – V1.0.59, 9–11 Oct 2026

• 4M removed from the Band dropdown and calibration tables; a new Tune button for a steady CW carrier; calibration Auto status and the Experimental IQ flyout; the CW settings page dropped its redundant Vol:/AGC: fields.

V1.0.46 – V1.0.54, 3–4 Oct 2026

• A round of phone-specific layout fixes after the new Audio/Mic/CW dropdowns made the page taller than the screen — the toolbar became a 6-column grid and the Filter slider became usable again; Menu > Calibration’s screens were enabled, sized for a phone; the waterfall switched to the T41’s own live colors with several brightness passes; and CW receive with Decode on gained the scrolling decoded-text strip.

V1.0.39 – V1.0.45, 2–3 Oct 2026

• New Audio, Mic and CW toolbar dropdowns and a plain Vol button, matching the desktop remote; arrow keys wired up to reach the Filter knob; the Nixie-tube frequency font redrawn; Menu/Display items started marking the current selection; and Display got its own toolbar dropdown, built as an accordion so its sub-menus fit a phone screen.

V1.0.27 – V1.0.38, 30 Sep – 2 Oct 2026

• The Menu > Diagnostics > I2C BIT test screen and a full-screen Receive IQ calibration screen were added; the SWR/PWR readout and the missing “(USB)” demod suffix were fixed; a mis-clocked audio playback rate that caused choppy sound (more reliably hit on phones than on the desktop page) was tracked down and fixed; the spectrum pane was shrunk and its readout strip moved into its own row; and Menu > Display was regrouped into sub-menus, opening inline (accordion-style) so four levels of nesting still fit a phone screen.

V1.0.18 – V1.0.26, 30 Sep 2026

• The readout strip above the spectrum grew Scale:, Floor: and RX DSP Gain entries, its font reduced to fit a phone width; Brightness became a single flyout instead of four flat entries; the spectrum trace’s fill color was matched to the waterfall’s own gradient; and the Audio Equalizer screen was added.

V1.0.6 – V1.0.17, 26–27 Sep 2026

• A run of phone-only layout fixes: toolbar dropdowns no longer overwrote their own fixed labels with the current value, the toolbar grid was rebuilt after it broke on an actual phone, the S-meter’s dBm reading and the frequency-scale ruler were fixed for real screen sizes, the on-screen version label stopped colliding with the Teensy’s own version readout (which was then dropped from this page entirely, see the Baseline entry below), and the page gained proper top/bottom safe-area padding for phones with a notch or home indicator.

V1.0.1 – V1.0.5 and earlier, 26 Sep 2026 and before Baseline

• The phone experience started as @media (pointer: coarse) rules bolted onto the desktop page — touch jog sliders for Tune/Fine Tune/Volume/Filter, a reordered status block, and a 4-column toolbar grid — until that media query turned out to also match the user’s own laptop trackpad and reflow the desktop page by mistake. The phone experience became its own file, remote_mobile.html, served at /mobile, with its own version label starting at V1.0.1. The desktop page (remote.html) was reverted back to a plain, pointer-detection-free layout the same day.

Full version-by-version detail: Detailed changelog: phone remote (/mobile) (PDF).

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Reference · how-to

Guides

Step-by-step setup instructions and procedures for the radio and its secondary CPU, collected here as they’re written. More will be added as the project goes on.

RTC Setup (DS3231)

How to add a battery-backed real-time clock to the Mustang 2’s Raspberry Pi 5, so it keeps accurate time in the field with no internet connection — needed for FT8, which requires the Pi’s clock to be within about 1 second of correct. Covers wiring an Adafruit PiRTC DS3231 breakout to the Pi’s GPIO header, including how its six unlabeled pins were identified, plus the setup script that keeps the clock synced.

Onboard RTC vs. DS3231: the Pi 5 has its own built-in real-time clock, but it only survives a power-off if a battery is added to its J5 connector — a small rechargeable cell (such as a LIR2032), not a plain coin cell. That cell self-discharges fairly quickly, holding time for only days to a few weeks unpowered. The DS3231’s own replaceable CR1220 coin cell holds accurate time for months to years unpowered instead, which matters more for a radio that sits unused between trips. If the radio gets powered up often enough to keep the Pi’s own battery topped off, the onboard RTC alone is simpler and needs none of the wiring or setup below.

• RTC Setup — Adafruit PiRTC DS3231PDF · 1.3 MB

Teensy USB Switch Wiring

How to wire an Adafruit TS3USB30 breakout and a DPDT toggle so the Teensy’s single Micro-USB port can be handed off between the Raspberry Pi and a programming cable with one flip — no unplugging cables inside the case. Covers the board’s actual silkscreened pinout (PORT1/USBHOST/PORT2), why VBUS needs its own switch pole instead of the board’s built-in pass-through, and the full wire-by-wire connection table.

• Teensy USB Switch WiringPDF · 273 KB

Mic Selector Switch

How to build a simple 2-input, 1-output 3.5 mm SPDT audio selector switch, so the T41’s front-panel MIC jack can be fed by either a real handheld mic or a Pi 5 USB audio adapter’s output, one at a time. Covers why a passive Y-splitter doesn’t work for this (it wires both sources together permanently, loading each other and risking the jack’s own mic-bias voltage backfeeding into the Pi’s sound card), the parts list, a wiring diagram, and step-by-step build and continuity-check instructions.

• Mic Selector Switch — Build GuidePDF · 154 KB

ATU-100 I2C Display Tap

Feasibility review and wiring plan for mirroring the N7DDC ATU-100 Extended Board’s OLED readout (PWR, SWR, L, C) onto the Pi 5’s own screen and both web remotes, via a passive tap on the ATU-100’s existing I2C display bus — no changes to the ATU-100’s PIC firmware. Covers why the bus’s slow bit-banged timing and the firmware’s known font table make true text decoding realistic (not just a pixel mirror), the mandatory 5V→3.3V level shifter, why the board needs 12V straight from the T41’s existing rail rather than a 5V supply, the parts list, a wiring diagram, and the recommended build order.

• ATU-100 I2C Display Tap — Feasibility & WiringPDF · 196 KB