VFO-Knob

A hardware VFO knob and control head for AetherSDR, FlexRadio and the Icom IC-705, built on the Waveshare ESP32-S3-Knob-Touch-LCD-1.8. Tune, change step, key the transmitter, watch the S-meter — over a USB-C cable or over WiFi. And, with its own firmware, a talkgroup knob for SvxLink reflectors.

 

Receiving, and transmitting, to scale in the 66 mm body. The readouts follow the bars. The meter blocks are notched in the background colour, so the separators appear where the bar has reached and vanish where it has not. Everything outside the body is annotation: the knob draws the S-meter scale as bare ticks, so its values are marked around the rim.

It speaks TCI v2.0 over a WebSocket, which is AetherSDR's own control protocol — so the knob is not polling, it is told. Tune at the desktop and the knob follows; turn the knob and the desktop moves.

With an IC-705 it talks to the radio itself, over WiFi, in Icom's network protocol — the one RS-BA1 and wfview use — with receive and transmit audio, so knob and radio are a complete station with no computer in between. Its face wears Icom's colours, so which radio a knob is for shows at a glance. The same firmware runs the IC-7610, with MAIN or SUB and its antennas on a swipe. See the Icom guide.

With a FlexRadio it is one of the radio's MultiFlex stations, over the radio's own API: a station of its own, with Opus audio both ways, or the dial and PTT for a SmartSDR, AetherSDR or Maestro station already on the radio. In the Maestro's colours. See FlexRadio.

With the svxconnect firmware there is no radio at all: the knob is an SvxLink reflector client over WiFi, in the style of SVXConnect and in its colours. The dial picks the talkgroup, the S-meter shows who is talking, and the built-in microphone and the jack are the station. See SvxLink reflectors.

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What it does

Tune	Per-digit step selection: tap a digit to set the decade. Acceleration on top, so a flick crosses a band and a slow turn lands on 10 Hz.
PTT	Toggle — tap to key, tap anywhere along the bottom to unkey. It keys as the finger lifts from a tap, so a swipe that starts on the bottom of the face never keys; on the air, a touch there unkeys at once. Nothing vibrates while you transmit: the motor sits beside the microphone and would be heard on the air, so the red screen alone says you are keyed, and you feel the unkey once the radio is back on receive. A four-rung teardown ends in dropping the socket. The transmit time-out is the radio's own.
Meters	S-meter in receive; SWR, auto-ranging forward power (to 2.5 kW) and mic level in transmit, each holding its peak for a second before it falls, so SSB reads as speech rather than flicker. The mic level uses AetherSDR's own scale: amber from −10 dB, red from 0. SWR above 2.5 turns its reading red.
Audio	RX audio out of the 3.5 mm jack, TX audio from the onboard mic, both with adjustable level. The built-in microphone is very good — clear, natural speech on the air, ideal for amateur radio — so the knob needs no headset or hand mic.
Mode / filter / RIT	Tap to open and turn to choose. Filter and RIT take effect as you turn, and a tap anywhere closes them; band and mode take a tap on their panel, and a tap anywhere else leaves them as they were.
AGC / gain	Either side of the S-meter's reading, edited like the filter: the AGC on the left, and on the right the front end's gain — P.AMP on the IC-705, RF.G on the FlexRadio, greyed out on AetherSDR until its TCI can carry it.
Memories	On the IC-705, V/M, last on the swipe down: MEMORY, and the frequency readout becomes the channel — its name, number, frequency, shift and tone — and the knob steps through the programmed channels of one group (tap the group, where the band was, to choose another). VFO again for the VFO, simplex.
Radios	Up to four per firmware on the configuration page — an IC-705 and an IC-7610, two FlexRadios, AetherSDR on two computers — and, on the FlexRadio firmware, the SmartLink account's. Swipe up, turn to one, tap on it: the knob restarts into it (SWITCHING TO …), with or without a link to the one it leaves; under the name, LAN or SmartLink says how it is reached. Not over the USB cable, which reaches one computer or one radio.
Gain, power, tuner	On the Icom firmware, swipe from the left for RF GAIN, and tap it for POWER, in watts; both apply as the knob turns (with a web SDR chosen, BALANCE comes first). Swipe from the right to put the IC-7610's antenna tuner in the line or out of it — only that: no tune cycle, nothing transmitted.
Web SDR	On the Icom, Xiegu and FlexRadio firmwares, a KiwiSDR, a Web-888 or an UberSDR as a second receiver beside the radio: swipe down, turn to LOCAL or a receiver, and tap. It follows the radio's frequency, mode and passband. The radio is in the left ear and the SDR in the right, brought to the same loudness, and BALANCE — first on the swipe from the left — fades from one to the other. See Web SDRs.
Network	Hold a finger on the S-meter until the knob clicks: the card with its addresses comes up; tap the card to put it away. With the card up, hold the S-meter again, until the knob buzzes, for the firmware picker.
Branding	RF.Guru boot splash in the palette of rfguru.app, over the site's own backdrop.

Two transports

The knob is USB-powered, so it is always plugged into something — and whatever runs AetherSDR is a computer with a USB port.

• USB-C (preferred). The knob enumerates as a USB network adapter (CDC-NCM), hands your machine an address and talks TCI over the cable. No configuration at all, and immune to what a machined metal case does to 2.4 GHz.
• WiFi. Configure an SSID on the configuration page and power the knob from any charger.

The cable wins whenever a computer is on the other end of it — the knob then waits for AetherSDR there rather than switching networks. With no computer on its side of the cable — a charger, or the plug the wrong way round — it goes to WiFi straight away. When the cable is chosen, WiFi is shut down — that frees about 40 kB of internal RAM, which this board genuinely needs.

First run

Knobs ship with the setup firmware, vfo-knob-setup: it puts the knob on your WiFi from a phone and installs the firmware for your radio. No computer needed. Step by step, with the knob's own screens: the setup guide (one guide per firmware in docs/).

1. The knob comes up as an open WiFi network, VFOKnob. Join it with a phone, and the phone opens the knob's sign-in page by itself (if it does not, browse to http://192.168.4.1).
2. Choose your network, enter its password — Show shows it as you type — and tap Connect. The page says whether the knob got on, and if not, why — a wrong password, a network out of reach — so you can try again.
3. The knob then lists the firmwares on its dial, with their versions: turn to yours and tap the panel to install it. It downloads the image, checks its signature and restarts into it, and the WiFi settings go with it.
4. Tell the knob where its radio is, on its configuration page: hold a finger on the S-meter, at the top of the face, until the knob clicks, and browse to the address on the card that comes up — user admin, password admin. Change the password; the page nags until you do, since it can key a transmitter.

The list comes from the update server each time, so a knob set up long after it was made still shows every firmware there is then. A knob that already knows a network joins it and goes straight to the list; the list's last entry, WIFI, brings the hotspot back to set up another.

Back to the list, from any firmware: hold a finger on the S-meter until the knob clicks and the address card comes up, and let go. Then hold the S-meter (or the card) again, for three seconds, until the knob buzzes. The dial asks FIRMWARE? — turn the knob for yes; a tap, or ten seconds of nothing, says no. The knob restarts, installs the setup firmware over WiFi and shows the list again, keeping the WiFi settings. With something wrong — NO LINK, say, on a knob with another radio's firmware — the warning panel shows the addresses in the card's place: hold that until the knob buzzes. It needs WiFi: on the cable the knob says so and carries on as it was.

AetherSDR over the cable

The AetherSDR firmware also runs over the USB-C cable, from the computer running AetherSDR (step by step: the AetherSDR guide):

1. Plug the knob into the computer running AetherSDR. Windows 10 (version 1903 or later), Windows 11, macOS and Linux all bring it up as a network adapter by themselves — there is nothing to install. The USB-C socket only works one way round: the other way it reaches the board's second chip, the knob finds no computer, and it says FLIP USB-C. Turn the plug over.
2. In AetherSDR, enable the TCI server — the TCI panel in the button bar — and set it to start automatically in Settings, so the knob finds it every time. That is the only setup on the computer.
3. Open http://10.55.42.1 — user admin, password admin.
4. Change the password. The page will nag until you do; it can key a transmitter.
5. If you want WiFi, set an SSID and the AetherSDR host. The host is only used on WiFi: over the cable the knob always talks to the computer it is plugged into.

If the page does not open

Give the knob about ten seconds after plugging in: for the first six it is a serial port, which keeps it flashable, and only then a network adapter.

1. FLIP USB-C on the knob, or the computer finds a USB Serial (CH340) port instead — USB\VID_1A86… in Windows' Device Manager: the plug is the wrong way round. Turn it over. With WiFi set up the knob only says so for a few seconds after the splash before carrying on over WiFi, so watch it start, or look for that CH340 port.
2. Windows. The knob is under Network adapters in Device Manager — Windows 10 names it after its driver, UsbNcm Host Device — with Hardware Ids (Properties → Details) starting USB\VID_303A&PID_4000. Windows 10 before version 1903 has no driver for it: update Windows, or set WiFi up once over the cable from a computer where it works and run the knob from a charger. Firmware 1.3.2 and older is the exception to "nothing to install": update it. Until then, on Windows 10 it shows as an unknown device (Code 28) and needs its driver chosen by hand — right-click → Update driver → Browse my computer for drivers → Let me pick from a list of available drivers on my computer → Network adapters → Microsoft, UsbNcm Host Device — and on an up-to-date Windows 11 it fails with Code 10, which no driver choice fixes.
3. Check the address. The computer's side of the link should be 10.55.42.2 (ipconfig on Windows). A 169.254.x.x address means it got no lease: renew it, or set 10.55.42.2, mask 255.255.255.0, no gateway and no DNS by hand. ping 10.55.42.1 should then answer.
4. Open the page with the scheme typed out, http://10.55.42.1/. If ping answers but the browser does not, a VPN or a proxy is taking the request — disconnect it, or add 10.55.42.* to the proxy exceptions.

WiFi instead of the cable. With no computer on its side of the cable the knob goes to WiFi by itself, a few seconds after powering up — so a charger is all it needs, once an SSID and the AetherSDR host have been set over the cable from a computer where it works. Plugged into a computer it stays on the cable even if that computer could not set the adapter up; keep a finger on the screen from plugging it in until the dial appears to skip USB networking for that boot.

If the knob says NO LINK

The page opens but the knob stays on NO LINK: either AetherSDR's TCI server is not running — see First run — or the computer's firewall is turning the knob away. The knob connects to AetherSDR, so the computer has to let it in.

Over the cable the link has no internet access, which is correct: nothing lies behind the knob. With no gateway on it, Windows lists it as Unidentified network and treats it as Public, so if AetherSDR's firewall prompt was answered for private networks only, the knob cannot reach AetherSDR's TCI port over the cable. Allow it once, from an administrator PowerShell — 50001 is AetherSDR's default; use the port set on the configuration page:

New-NetFirewallRule -DisplayName "VFO-Knob TCI (USB)" -Direction Inbound `
  -Protocol TCP -LocalPort 50001 -RemoteAddress 10.55.42.1 -Action Allow -Profile Any

A Block rule always beats an Allow, and that prompt may have left one for AetherSDR on public networks. If the rule above changes nothing, open Windows Defender Firewall with Advanced Security (wf.msc), find AetherSDR's Public TCP rule under Inbound Rules, switch it from Block to Allow, and on its Scope tab set Remote IP address to 10.55.42.1. Left unscoped, that opens AetherSDR's TCI port — which can key the transmitter — to everyone on every public network the computer joins.

A Linux firewall that drops inbound connections by default (ufw, or firewalld's public zone) stops the knob the same way — on the cable, and on WiFi from wherever your network puts it. Let both in once, e.g. sudo ufw allow proto tcp from 10.55.42.1 to any port 50001 for the cable and sudo ufw allow proto tcp from 192.168.1.0/24 to any port 50001 with your own LAN's range for WiFi.

FlexRadio (MultiFlex)

The multiflex firmware (vfo-knob-multiflex) talks to a FLEX-6000 or FLEX-8000 itself, over the radio's own API on the LAN — no SmartSDR, no AetherSDR, no computer. Step by step: the FlexRadio guide. The knob is one of the radio's MultiFlex stations, beside SmartSDR, AetherSDR or a Maestro, in the Maestro's colours.

At boot the knob looks at who is already on the radio and, if anyone is, asks on the dial what to be:

• STATION OWN — a station of its own. Its own slice, which the radio gives back where it was after a restart; its own audio both ways, as Opus over WiFi, so the speaker and the built-in microphone are the station; and its own transmit settings, which leave the other stations' alone.
• DIAL FOR station — the dial and PTT for a station already there, like a FlexControl on its computer. The knob works that station's active slice, and follows when its operator clicks another; PTT keys that station's transmitter, with that station's microphone. The knob plays no audio.

The last choice is offered first, and taken after 30 s without an answer. With nobody else on the radio the knob does not ask.

The dial	Tunes the slice. Mode, filter, AGC, RIT and RF.G — the panadapter's RF gain, which the radio's API carries — are edited as on the other radios.
Swipe from the right	TUNE, a carrier at the tune power, for an external tuner or to check SWR — PTT stops it, and it stops by itself after 30 s. ATU, one cycle of the radio's tuner. MEM, the tuner's memories, lit when on; a tap switches them and the menu stays. The menu opens on MEM: TUNE and ATU are a turn away.
PTT	Refused with the reason when the radio will not transmit here: out of band, or another station on the air.

The radio is given by its IP address on the configuration page, and MultiFlex must be enabled on it. Finding the radio by its discovery broadcast is still to come.

SmartLink

A radio away from home is reached through FlexRadio's own service, as SmartSDR and AetherSDR reach it. Log in under SmartLink on the configuration page with the account's email address and password: the password goes to FlexRadio's login service and is not kept — the knob keeps the login it is given, until you log out there. The account's radios are listed, and with Offer these radios on the knob they come after the configured ones on the swipe up, marked SmartLink under the name; LAN marks the direct ones. The same radio can be in the list both ways.

Chosen, the knob restarts into it: SmartLink's server introduces the knob to the radio, which it then reaches over TLS. The radio's certificate is its own, self-signed; the knob pins it the first time, as AetherSDR does, and refuses a different one until you log in again. After that it is the same station as on the LAN, Opus audio and PTT included. A radio reachable only by hole punching — neither a forwarded port nor UPnP — is listed but not yet connected to.

Web SDRs

On the Icom, Xiegu and FlexRadio firmwares the knob can listen to a web SDR beside the radio — a KiwiSDR, a Web-888, or an UberSDR through its Kiwi input; all three speak KiwiSDR's protocol. Up to four are kept, added on the configuration page with their address (host:port — 8073 on most KiwiSDRs), a password where the receiver has one, and its time-limit password, which lifts the listening limit some receivers put on each address. The address is the receiver's own plain http:// one: not an https:// link through a proxy or a tunnel.

Swipe down	RX: turn through LOCAL and the receivers by name, tap to listen. The IC-7610 then goes on to MAIN/SUB and the antenna for the radio's side, whichever was chosen: with an SDR the radio still plays in the left ear. The IC-705 goes on to V/M.
Listening	The SDR follows the radio: frequency, mode and passband, retuned as the dial turns. The radio is in the left ear and the SDR in the right, both levelled to the same loudness.
Its S-meter	A thin blue line just outside the radio's S-meter, on the same scale, and its reading in blue under the radio's, where the dBm is otherwise: S9+20 against the radio's S7. Dots while it connects; a word, in amber, when it cannot — busy, no apps, password?, day limit, no answer.
Balance	First on the swipe from the left while an SDR is chosen; a tap on it goes on to RF GAIN and POWER. From RADIO, the radio alone, through L | R to SDR, the SDR alone.
Transmitting	The SDR goes quiet: it would play the over back a second late, and from a speaker the microphone would hear it.

Test, beside each receiver on the configuration page, logs in and says what the receiver calls itself, how many of its channels are in use, and whether the password is right. It also says when a receiver's owner lets no apps listen: a KiwiSDR can keep its channels for browsers, and a client without a waterfall — the knob is one — is cut off after ten seconds. The knob tries such a receiver once and then leaves it alone until it is chosen again. It waits two minutes when the channels for apps are all in use, and half an hour when the day's listening limit has been reached.

The choice is on the radio page too, and in its API: sdr=local or sdr=0 to 3, by the receiver's place in the list, and balance=-100 to 100.

SvxLink reflectors

The svxconnect firmware (vfo-knob-svxconnect) turns the knob into a node on an SvxLink reflector: protocol 3.0, the reflector's own TLS with a client certificate, Opus audio both ways at 16 kHz. It is a port of SVXConnect-CLI's reflector client, and shares its protocol code, talkgroup manager and codec settings. Step by step: the SvxLink guide.

The face is the radio face, read differently:

The dial	Steps through the switchable talkgroups, one a detent. The talkgroup's name, from the reflector's portal, is where the frequency is — looping when it is long — with the reflector under it; TG n is where band and mode are.
Lock	Left of the talkgroup: no switching, by the dial or by a busier talkgroup.
Mute	Right of it: the speaker off, the talkgroup still selected, who is talking still shown.
Meter	The received audio in dBFS, and in transmit the microphone. Above it, who is talking — with where they are, when the reflector publishes it — or who spoke last and how long ago.
PTT	Tap to key, tap to unkey, as on the radios. The reflector's own announcement of your callsign confirms the key; on a busy talkgroup it refuses you the floor and the knob says so with the refusal click.
Link	Where the step is: connected, connecting or disconnected.

Talkgroups follow SVXConnect's rules: switchable ones are on the dial, monitored ones are followed when there is traffic, a + after a number raises its priority (9990, 8++, 1745+), the knob stays on a talkgroup for a while after an over, and drops back to monitoring after a quiet spell. With no lists set it steps through every talkgroup the reflector's portal names.

First run

1. Set the WiFi on the configuration page, and the reflector: its name, not its host — be.svx.link is found through its SRV record.
2. Under Station, give your callsign and an email address; the location and position are for the reflector's map.
3. Press Request certificate. The knob makes its RSA key (a few seconds), sends the reflector a certificate request and keeps asking every 30 s until the sysop has signed it, then logs in by itself. The certificate renews by itself; the key never changes, because the reflector knows the callsign by it.

On an enhanced reflector

Where the reflector has a portal, the knob reads its talkgroups.json for the names (kept in flash, refreshed daily) and follows its live feed for where each talker is. The feed is a second connection to the same host; the knob pauses it while it logs in, and it can be switched off on the configuration page.

Configuration page

Served on port 80 over whichever interface is up. Status, AetherSDR endpoint, WiFi credentials, audio levels, access credentials, and firmware updates.

Opened over WiFi, the host field offers a green my IP — the address of the computer you are browsing from, one tap to fill in when that is where AetherSDR runs. Over the cable it is not offered: there the knob finds AetherSDR by itself, and the cable's 10.55.42.2 would mean nothing on WiFi, the only place the host setting is used.

The radio section is a list: up to four radios, each with a name for the dial, and one In use — chosen here for the next start, or with a swipe up on the knob, which restarts into it at once. (The reflector firmware keeps its single reflector.) On the FlexRadio firmware a SmartLink section below it logs in to FlexRadio's service and lists the account's radios, each with Use now — see SmartLink.

With the radio connected, the page opens on its controls instead, in the knob's own colours: the frequency, typed or stepped, band, mode, filter, AGC, the preamp or RF gain, power, the tuner, MAIN/SUB and the antenna, RIT, the web SDR and its balance, and the knob's volume and mic gain — everything the knob can set on the radio, and nothing that transmits. Config leads to the settings above, the radio staying connected.

The same, for other programs — a logbook reading the frequency and mode, or anything setting them with a URL:

GET /api/radio                        the state, as JSON
GET /api/radio/set?freq=14074000      Hz, or MHz with a point (14.074)
    ...&mode=usb&filter=2&agc=mid&rfgain=80&power=50&tuner=on&rit=-120
    ...&sdr=0&balance=-30             a web SDR beside the radio, "local" for none
GET /api/radios                       the radios the knob knows, and the one in use
POST /api/radios/switch  to=1         another in use: the knob restarts into it

A POST with the same fields as a form does the same. Both need the page's login (http://user:password@<knob>/api/radio), and no setting is taken while the radio is on the air.

It is HTTP Basic over plain HTTP. A lock on the door, not a safe — treat the knob as something that belongs on a network you trust.

Updates

Images are RSA-3072 signed and the signature is checked before an update is accepted. Nothing is burned into eFuse and Secure Boot is not enabled, so the board always stays ordinarily flashable — this protects the update path, not the hardware.

• On WiFi the knob checks by itself — at boot, and every 24 h by default — and asks on the dial: UPDATE x.y.z, tap here to install. A tap on the question installs it and restarts into it; anything else — ten seconds, a turn of the knob, a tap elsewhere — and the question goes away and the dial carries on. It never asks while transmitting, and never installs unasked. A yes given mid-session restarts the knob first and installs at boot, where there is room for it. Set the interval to 0 on the configuration page to stop checking.
• Over USB the knob has no route to the internet — it is the DHCP server on that link. The configuration page does the checking and the downloading instead, then pushes the image over. Same image, same signature check.

If an update fails to boot, the bootloader rolls back to the previous slot. The confirmation is tied to the same "this boot looks healthy" timer that clears the boot-loop guard.

There is one firmware per radio, vfo-knob-<radio> — vfo-knob-aethersdr, vfo-knob-icom, vfo-knob-multiflex and vfo-knob-svxconnect — and each has its own update channel, firmware/<radio>/, so a knob is only ever offered its own releases. It also refuses to install another radio's firmware as an update; switching radios is a deliberate choice under Firmware on the configuration page, or on the dial through the setup firmware, vfo-knob-setup.

Publishing a release: tools/release.sh 1.2.3 --push (another radio's: RADIO=<radio> tools/release.sh …). Each release also rewrites firmware/index.json, the list the setup firmware shows, from the channels' manifests.

Building

Needs ESP-IDF 5.5.x.

idf.py -B build_usbnet \
       -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.usbnet" \
       build flash

Leave off sdkconfig.usbnet for a WiFi-only build that keeps the serial console. No credentials are compiled in — a unit ships with empty storage and is configured over the cable.

The IC-705 firmware is WiFi only (the radio is reached over WiFi, and the USB link has no route to it):

idf.py -B build_icom -D VFO_RADIO=icom \
       -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.icom" \
       build flash

So are the multiflex, svxconnect and setup firmwares:

idf.py -B build_multiflex -D VFO_RADIO=multiflex \
       -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.multiflex" \
       build flash
idf.py -B build_svxconnect -D VFO_RADIO=svxconnect \
       -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.svxconnect" \
       build flash
idf.py -B build_setup -D VFO_RADIO=setup \
       -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.setup" \
       build flash

Host-side tests (no hardware, no ESP-IDF):

cmake -S test/host -B build_host && cmake --build build_host && (cd build_host && ctest)

tools/mock_aether.py is a fault-injecting TCI server for exercising the error paths without a radio.

To try the face's touch with nothing keyed, -D VFO_PTT_DRY_RUN=1 builds an image whose PTT taps are only logged, never sent to the radio; its slab reads PTT TEST. Never for a release.

Recovering a knob

Once TinyUSB owns the USB pads there is no serial port, and this board makes that awkward: GPIO0 doubles as the audio mux behind a single button inside the case, and the other Type-C plug orientation reaches the board's second chip, not the ESP32-S3. So the firmware leaves its own way back in.

• Every boot holds the ROM serial port open for 6 seconds before starting USB networking. idf.py flash catches it.
• The PHY mux is put back to serial on every startup — it lives in the RTC domain and survives a reset, so without that a crash would come back with no serial port at all.
• echo reboot | nc <knob-ip> 3333 restarts it remotely and opens that window.
• Holding a finger on the screen through boot skips USB networking entirely.

Port 3333 is also a log stream — the USB build has no console, so it is the only way to watch a boot.

Safety

The knob keys a transmitter. Two things are worth knowing:

• Toggle PTT means the radio stays keyed when you let go. That is why the very loud red screen exists (there is no haptic reminder: on the air the motor would be heard through the microphone), and why the radio's transmit time-out should be set: in AetherSDR, Radio Setup → TX → Timeout. The radio enforces it itself, so it holds even if the knob, the link or the computer does not. The knob no longer keeps a second one.
• A client that loses power while keyed cannot unkey itself. No firmware on this device can fix that; the server has to notice. Filed upstream as aethersdr#5985. On a FlexRadio the knob as a station of its own is safe from this: the radio stops a station's transmission when it leaves. As the dial for another station it is not — that station is still there — so try it before relying on it: key from the knob, pull its power, and see what the radio does. The radio's transmit time-out is the backstop.

Hardware

Waveshare ESP32-S3-Knob-Touch-LCD-1.8: ESP32-S3 with 16 MB flash and 8 MB PSRAM, 360×360 round SH8601 display, CST816 touch, DRV2605L haptics, PCM5100A DAC and a PDM microphone. Every GPIO number lives in components/board/board_pins.h.

Licence

Apache-2.0. You may use, modify, sell and ship this firmware, including on hardware you sell, with no obligation to publish your changes. It carries an explicit patent grant. Keep the LICENSE and NOTICE files with any redistribution, and state what you changed.

The display initialisation table in components/panel/sh8601_init_cmds.c comes from Waveshare's demo for this board. Waveshare confirmed on enquiry that their ESP32 demo code is Apache-2.0, so it carries the same terms as the rest and redistributes cleanly. Full list in THIRD_PARTY_LICENSES.