[Bug]: SEED ESP32S3 & WIO SX1262, "No Interface" Error When Setting GPS RX/TX Pins in Meshtastic App

[Genei180]

Category

Hardware Compatibility

Hardware

Other

Is this bug report about any UI component firmware like InkHUD or Meshtatic UI (MUI)?

• Meshtastic UI aka MUI colorTFT
• InkHUD ePaper
• OLED slide UI on any display

Firmware Version

2.6.4.b89355f (Stabel Beta)

Description

Summary:
After flashing two devices with the firmware, they can successfully exchange messages. However, when attempting to set up a GPS module via the Meshtastic app and Bluetooth, critical issues occur.

Steps to Reproduce:

• Connect to the device via Bluetooth using the Meshtastic app.
• Open the Position Settings.
• Set RX to Pin 6 and TX to Pin 7 (attempting to connect a Neo-6M-0-001 GPS module).

Observed Behavior:

• The app immediately shows "Error: Disconnected", without displaying the usual loading/progress bar, and then the device reboots.
• After reboot, the position settings are updated, but:
  • Sending a message results in "Queued for Sending" for a long time, followed by "No Interface".
  • Additional settings cannot be sent.
  • Attempting to reset RX/TX pins to 0 causes the settings progress bar to stay at 0%.
  • Waiting long enough (~5-10min) Reboots the Device, the GPS Pins are reset and message sending works again.

Hardware Context:

• The device is an ESP32-S3 variant with the Wio SX1262 module.
• Initially suspected a pin conflict due to shared ESP32's IO Pins and B2B header Pins connecting to the Module
• However, tried multiple combinations (First D9/D10 then D6/D7), and the same issue occurs.
• According to this forum post, the pins (D6/D7) should be available.

Any guidance on avoiding this issue or clarification how it's meant to work would be greatly appreciated.

Thanks a lot!

Relevant log output

DEBUG | 11:26:46 139 [Router] Save to disk 1

DEBUG | 11:26:46 139 [Router] Opening /prefs/config.proto, fullAtomic=1

INFO | 11:26:47 139 [Router] Save /prefs/config.proto

INFO | 11:26:47 139 [Router] Reboot in 7 seconds

DEBUG | 11:26:47 139 [Router] Module 'Admin' considered

DEBUG | 11:26:47 139 [Router] Module 'routing' wantsPacket=1

INFO | 11:26:47 139 [Router] Received routing from=0x0, id=0x956a644d, portnum=6, payloadlen=36

DEBUG | 11:26:47 139 [Router] Routing sniffing (id=0x956a644d fr=0x00000000 to=0xda73eb3c, WantAck=1, HopLim=3 Ch=0x0 Portnum=6 rxtime=1746444406 priority=70)

DEBUG | 11:26:47 139 [Router] Partially randomized packet id 4192801509

DEBUG | 11:26:47 139 [Router] Enqueued local (id=0xf9e912e5 fr=0xda73eb3c to=0xda73eb3c, WantAck=0, HopLim=3 Ch=0x0 Portnum=5 requestId=956a644d rxtime=1746444407 priority=120)

DEBUG | 11:26:47 139 [Router] Module 'routing' considered

DEBUG | 11:26:47 139 [Router] Rx someone rebroadcasting for us (id=0xf9e912e5 fr=0xda73eb3c to=0xda73eb3c, WantAck=0, HopLim=3 Ch=0x0 Portnum=5 requestId=956a644d rxtime=1746444407 priorit

DEBUG | 11:26:47 139 [Router] Didn't find pending packet

DEBUG | 11:26:47 139 [Router] Add packet record fr=0xda73eb3c, id=0xf9e912e5

DEBUG | 11:26:47 139 [Router] handleReceived(REMOTE) (id=0xf9e912e5 fr=0xda73eb3c to=0xda73eb3c, WantAck=0, HopLim=3 Ch=0x0 Portnum=5 requestId=956a644d rxtime=1746444407 priority=120)

DEBUG | 11:26:47 139 [Router] Module 'routing' wantsPacket=1

INFO | 11:26:47 139 [Router] Received routing from=0xda73eb3c, id=0xf9e912e5, portnum=5, payloadlen=2

DEBUG | 11:26:47 139 [Router] Routing sniffing (id=0xf9e912e5 fr=0xda73eb3c to=0xda73eb3c, WantAck=0, HopLim=3 Ch=0x0 Portnum=5 requestId=956a644d rxtime=1746444407 priority=120)

DEBUG | 11:26:47 139 [Router] Received a ACK for 0x956a644d, stopping retransmissions

DEBUG | 11:26:47 139 [Router] Delivering rx packet (id=0xf9e912e5 fr=0xda73eb3c to=0xda73eb3c, WantAck=0, HopLim=3 Ch=0x0 Portnum=5 requestId=956a644d rxtime=1746444407 priority=120)

DEBUG | 11:26:47 139 [Router] Update DB node 0xda73eb3c, rx_time=1746444407

DEBUG | 11:26:47 139 [Router] Forwarding to phone (id=0xf9e912e5 fr=0xda73eb3c to=0xda73eb3c, WantAck=0, HopLim=3 Ch=0x0 Portnum=5 requestId=956a644d rxtime=1746444407 priority=120)

DEBUG | 11:26:47 139 [Router] Module 'routing' considered

DEBUG | 11:26:53 145 [Power] Battery: usbPower=1, isCharging=1, batMv=6368, batPct=100

INFO | 11:26:54 146 Rebooting

[lagunacomputer]

if you can compile your own firmware, try adding the following to your variant.h file.

#define HAS_GPS 1
#define GPS_UBLOX

or

#define HAS_GPS 1
#define GPS_UBLOX
#define GPS_RX_PIN 6
#define GPS_TX_PIN 7

re:
firmware/variants/seeed_xiao_s3
/variant.h

/*Warning:
https://www.seeedstudio.com/L76K-GNSS-Module-for-Seeed-Studio-XIAO-p-5864.html
L76K Expansion Board can not directly used, L76K Reset Pin needs to override or physically remove it,
otherwise it will conflict with the SPI pins
*/
#define GPS_L76K
#ifdef GPS_L76K
#define GPS_RX_PIN 44
#define GPS_TX_PIN 43
#define HAS_GPS 1
#define GPS_BAUDRATE 9600
#define GPS_THREAD_INTERVAL 50
#define PIN_SERIAL1_RX PIN_GPS_TX
#define PIN_SERIAL1_TX PIN_GPS_RX
#define PIN_GPS_STANDBY 1
#endif

[Genei180]

Thanks for your Suggestion!
highly Appreciate it.

This only helps somewhat.
The Pins are now Set RIght, but the Module still is not Detected.
Tryed with:

#define GPS_DEBUG 1
#define HAS_GPS 1
#define GPS_UBLOX
#define GPS_RX_PIN 6
#define GPS_TX_PIN 7
#define GPS_BAUDRATE 9600 

In the Variant.h

Log

DEBUG | ??:??:?? 5 Pin EN HI
DEBUG | ??:??:?? 5 Use GPIO6 for GPS RX
DEBUG | ??:??:?? 5 Use GPIO7 for GPS TX
DEBUG | ??:??:?? 5 Start multicast thread
DEBUG | ??:??:?? 5 NeighborInfoModule is disabled
DEBUG | ??:??:?? 5 Rescan for I2C keyboard
DEBUG | ??:??:?? 5 Scan for I2C devices on port 1
DEBUG | ??:??:?? 5 Scan address 0x1f
DEBUG | ??:??:?? 6 Scan address 0x34
DEBUG | ??:??:?? 7 Scan address 0x55
DEBUG | ??:??:?? 8 Scan address 0x5a
DEBUG | ??:??:?? 9 Scan address 0x5f
INFO | ??:??:?? 10 External Notification Module Disabled
DEBUG | ??:??:?? 10 SX126xInterface(cs=41, irq=39, rst=42, busy=40)
DEBUG | ??:??:?? 10 SX126X_DIO3_TCXO_VOLTAGE defined, using DIO3 as TCXO reference voltage at 1.800000 V
INFO | ??:??:?? 10 Start meshradio init
INFO | ??:??:?? 10 Radio freq=906.875, config.lora.frequency_offset=0.000
INFO | ??:??:?? 10 Set radio: region=UNSET, name=LongFast, config=0, ch=19, power=30
INFO | ??:??:?? 10 myRegion->freqStart -> myRegion->freqEnd: 902.000000 -> 928.000000 (26.000000 MHz)
INFO | ??:??:?? 10 numChannels: 104 x 250.000kHz
INFO | ??:??:?? 10 channel_num: 20
INFO | ??:??:?? 10 frequency: 906.875000
INFO | ??:??:?? 10 Slot time: 28 msec
INFO | ??:??:?? 10 Set radio: final power level=22
INFO | ??:??:?? 21 SX126x init result -2
WARN | ??:??:?? 21 No SX1262 radio
INFO | ??:??:?? 21 Not using WIFI
ERROR | ??:??:?? 21 NOTE! Record critical error 3 at src/main.cpp:1281
INFO | ??:??:?? 21 PowerFSM init, USB power=1
DEBUG | ??:??:?? 21 State: BOOT
DEBUG | ??:??:?? 21 Free heap : 209612 bytes
DEBUG | ??:??:?? 21 Free PSRAM : 8347211 bytes
DEBUG | ??:??:?? 21 [Power] Battery: usbPower=0, isCharging=0, batMv=3100, batPct=0
DEBUG | ??:??:?? 21 [GPS] Probe for GPS at 9600
DEBUG | ??:??:?? 21 [GPS] Trying $PDTINFO (Unicore Family)...
DEBUG | ??:??:?? 21 [GPS]
DEBUG | ??:??:?? 21 [GPS] Trying $PCAS06,1*1A (ATGM33xx Family)...
DEBUG | ??:??:?? 22 [GPS]
DEBUG | ??:??:?? 22 [GPS] Trying $PAIR021*39 (Airoha Family)...
DEBUG | ??:??:?? 23 [GPS]
DEBUG | ??:??:?? 23 [GPS] Trying $PQTMVERNO*58 (LC86)...
DEBUG | ??:??:?? 23 [GPS] Trying $PCAS06,0*1B (L76K)...
DEBUG | ??:??:?? 24 [GPS] Trying $PMTK605*31 (MTK Family)...
DEBUG | ??:??:?? 25 [GPS]
DEBUG | ??:??:?? 25 [GPS]
WARN | ??:??:?? 25 [GPS] No response for class 06 message 08
WARN | ??:??:?? 25 [GPS] No GNSS Module (baudrate 9600)
INFO | ??:??:?? 25 [RangeTest] Range Test Module - Disabled
INFO | ??:??:?? 25 [PowerFSM] Loss of power in Powered
INFO | ??:??:?? 25 [PowerFSM] Loss of power in Powered
INFO | ??:??:?? 25 [PowerFSM] Init the NimBLE bluetooth module
DEBUG | ??:??:?? 25 [PowerFSM] State: ON
DEBUG | ??:??:?? 27 [GPS] Probe for GPS at 9600
DEBUG | ??:??:?? 27 [GPS] Trying $PDTINFO (Unicore Family)...
DEBUG | ??:??:?? 28 [GPS]
DEBUG | ??:??:?? 28 [GPS] Trying $PCAS06,1*1A (ATGM33xx Family)...
DEBUG | ??:??:?? 29 [GPS]
DEBUG | ??:??:?? 29 [GPS] Trying $PAIR021*39 (Airoha Family)...
DEBUG | ??:??:?? 30 [GPS]
DEBUG | ??:??:?? 30 [GPS] Trying $PQTMVERNO*58 (LC86)...
DEBUG | ??:??:?? 30 [GPS] Trying $PCAS06,0*1B (L76K)...
DEBUG | ??:??:?? 31 [GPS] Trying $PMTK605*31 (MTK Family)...
DEBUG | ??:??:?? 31 [GPS]
DEBUG | ??:??:?? 32 [GPS]
WARN | ??:??:?? 32 [GPS] No response for class 06 message 08
WARN | ??:??:?? 32 [GPS] No GNSS Module (baudrate 9600)
DEBUG | ??:??:?? 32 [GPS] Probe for GPS at 9600
DEBUG | ??:??:?? 32 [GPS] Trying $PDTINFO (Unicore Family)...
DEBUG | ??:??:?? 33 [GPS]
DEBUG | ??:??:?? 33 [GPS] Trying $PCAS06,1*1A (ATGM33xx Family)...
DEBUG | ??:??:?? 33 [GPS]
DEBUG | ??:??:?? 33 [GPS] Trying $PAIR021*39 (Airoha Family)...
DEBUG | ??:??:?? 34 [GPS]
DEBUG | ??:??:?? 34 [GPS] Trying $PQTMVERNO*58 (LC86)...
DEBUG | ??:??:?? 35 [GPS] Trying $PCAS06,0*1B (L76K)...
DEBUG | ??:??:?? 35 [GPS] Trying $PMTK605*31 (MTK Family)...
DEBUG | ??:??:?? 36 [GPS]
DEBUG | ??:??:?? 37 [GPS]
WARN | ??:??:?? 37 [GPS] No response for class 06 message 08
WARN | ??:??:?? 37 [GPS] No GNSS Module (baudrate 9600)
WARN | ??:??:?? 37 [GPS] Give up on GPS probe and set to 9600

Was Inside and the GPS had no Satellite Connection, maybe thats Part of the Problem?
But i atleast expect it to somehow communicate and Show up.

Side Note:
I tried with the Pins the other Way around, and when compiling over PlatformIO the GPS Pins Stayed in Flash Memory after Reupload.
So the Re-upload had no Effect on Changed Pins.
Had to Update it via, the Online Meshtastic Erase&Install, to be able to reflash it fully via VS Code.

[Genei180]

I since found out the GPS Module was broken, because the GPS Neo 6M LED was never flashing even Outside.
Since then, I replaced it with a new Module, the LED Flashes now.

And the Arduino Sketch Provided here:
https://wiki.seeedstudio.com/get_start_l76k_gnss/
Works for the Neo 6M too.
I can log out GPS Data.

Unfortunately, Meshtastic doesn't recognize the GPS Module.
Any help or Guidance Moving Forward is appreciated.

[lagunacomputer]

try 44/43 or 43/44 instead of 6/7 or 7/6

#define GPS_RX_PIN 44
#define GPS_TX_PIN 43

re:
https://www.seeedstudio.com/XIAO-ESP32S3-p-5627.html
and

firmware/variants/seeed_xiao_s3
/variant.h

/*Warning:
https://www.seeedstudio.com/L76K-GNSS-Module-for-Seeed-Studio-XIAO-p-5864.html
L76K Expansion Board can not directly used, L76K Reset Pin needs to override or physically remove it,
otherwise it will conflict with the SPI pins
*/
#define GPS_L76K
#ifdef GPS_L76K
#define GPS_RX_PIN 44
#define GPS_TX_PIN 43
#define HAS_GPS 1
#define GPS_BAUDRATE 9600
#define GPS_THREAD_INTERVAL 50
#define PIN_SERIAL1_RX PIN_GPS_TX
#define PIN_SERIAL1_TX PIN_GPS_RX
#define PIN_GPS_STANDBY 1
#endif

[fifieldt]

Hi, just confirming that Ublox 6 is supported .

To take some of the guesswork out, you can add
define GPS_DEBUG 1
in your variant.h
and that will print every message sent on the serial bus.

If you don't see any messages, there is probably a problem with your pins

[Genei180]

Hey all Thanks for the Help.

I advanced a little. There were Multiple Problems, some of them really Stupid, but I am just getting started, so thanks a lot for your Time.

First Problem, was 3 of the 5 Ublox 6 Module I bought were somehow broken or didn't React at all on the Serial Connection.

The Second Problem, thanks @lagunacomputer for pointing that out, is that there are Actually TX and RX Pins at 43 and 44.
See

I thought I can just use the ones mentioned, on the Board D6 & D7, this is not the Case.
Pin 43 and 44 need to be used Accordingly. (Quite unintutive on a Chip with 10 Pins)

Additionally, as you expect from a Serial Connection, RX GPS needs to Connect to the TX Pin Configured in Meshtastic.
Not TX Pin Configured in Meshtastic to TX Pin on GPS.

Additionally, I am unsure what the PlatformIO Plugin in VS Code actually Uploads and Resets.
Making it even further Unintuitive what works and what not.
Most of the Time, the settings seem to be made Persistent across Uploads.
Keeping Pins changed via the Android Settings, even when others were Specified in the Code.
Additionally, I had no way of Knowing if the Android Settings Applied Successfully as it's always stuck at 0%, after a while you can observe the Module Rebooting in the Logs (reason for me Unknown). Most of the Time they were applied after.
But this introduced a further Uncertainty, making it even more complicated for me.

With the Original Code provided in this Repo for the XIAO ESP32S3, i had no Success connecting the Ublox 6 Module.
Neither with Setting the Pins in the App nor in code.

The Only way i got the GPS Module to Connect was with the Following Code:

#define GPS_DEBUG 1
#define HAS_GPS 1
#define GPS_UBLOX
#define GPS_RX_PIN 43
#define GPS_TX_PIN 44
#define GPS_BAUDRATE 9600 

Thanks @lagunacomputer for suggesting it.

Interestingly, then setting via the Android App or Compiling the Pins in were both Possible.

If I can provide further Information, or should try out something, let me know.

Thanks a lot for the Support, and helping me work it out.