Need help getting Ublox GPS going with Meshtastic/Pico

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43

Ok, all appears to be working properly (now my brain is!)
Correct position, elevation and time on node with GPS and correct time on other nodes.

44

Nice.

for others following along. I did the reading and research then created a variant config to enable GPS on pins GPIO 0/1. This was mainly based on work done by others, just not ported.

Pro, it works, Con, not yet part of the core up-stream.

So if you happy to compile your own firmware, the follow is the two files used in my variant.

I create a variant folder called

rpipico-gps

pioplatformio.ini (based on the original rpipico variant)

[env:pico-gps]
extends = rp2040_base
board = rpipico
upload_protocol = picotool

# add our variants files to the include and src paths
build_flags = ${rp2040_base.build_flags} 
  -DRPI_PICO
  -Ivariants/rpipico-gps
  -DDEBUG_RP2040_PORT=Serial
  -DHW_SPI1_DEVICE
lib_deps =
  ${rp2040_base.lib_deps}
debug_build_flags = ${rp2040_base.build_flags}, -g
debug_tool = cmsis-dap ; for e.g. Picotool

really its only two changes

[env:pico-gps]

and

-Ivariants/rpipico-gps

Then added some lines to variant.h

/ #define RADIOLIB_CUSTOM_ARDUINO 1
// #define RADIOLIB_TONE_UNSUPPORTED 1
// #define RADIOLIB_SOFTWARE_SERIAL_UNSUPPORTED 1

#define ARDUINO_ARCH_AVR

// default I2C pins:
// SDA = 4
// SCL = 5

// Recommended pins for SerialModule:
// txd = 8
// rxd = 9

#define HAS_GPS 1

#define GPS_RX_PIN 0
#define GPS_TX_PIN 1

// No GPS reset available
#undef PIN_GPS_RESET

#define EXT_NOTIFY_OUT 22
#define BUTTON_PIN 17

#define LED_PIN PIN_LED

#define BATTERY_PIN 26
// ratio of voltage divider = 3.0 (R17=200k, R18=100k)
#define ADC_MULTIPLIER 3.1 // 3.0 + a bit for being optimistic
#define BATTERY_SENSE_RESOLUTION_BITS ADC_RESOLUTION

#define USE_SX1262

#undef LORA_SCK
#undef LORA_MISO
#undef LORA_MOSI
#undef LORA_CS
#define LORA_SCK 10
#define LORA_MISO 12
#define LORA_MOSI 11
#define LORA_CS 3

#define LORA_DIO0 RADIOLIB_NC
#define LORA_RESET 15
#define LORA_DIO1 20
#define LORA_DIO2 2
#define LORA_DIO3 RADIOLIB_NC

#ifdef USE_SX1262
#define SX126X_CS LORA_CS
#define SX126X_DIO1 LORA_DIO1
#define SX126X_BUSY LORA_DIO2
#define SX126X_RESET LORA_RESET
#define SX126X_DIO2_AS_RF_SWITCH
#define SX126X_DIO3_TCXO_VOLTAGE 1.8
#endif

Really it was just adding the following lines

#define HAS_GPS 1

#define GPS_RX_PIN 0
#define GPS_TX_PIN 1

// No GPS reset available
#undef PIN_GPS_RESET

So feel free to take as is if you compile your own code.
In theory you should be able to tweak for the picow pico2 and pico2w; but I dont have those modules to test. If you to have one of those and want to test, let me know and I will give you a u2f file to test with a uart based GPS.

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45

Entirely due to Michael99645 's generosity with his time the Pico/Waveshare LoRa now works with the Ublox GPS. However there is a remaining problem that is so far proving difficult to resolve so I am wondering if anyone else may have useful input.
After very close to 8 hours running with the GPS attached the Pico locks up. The OLED display stops updating and the green LED on the Pico is either off, permanently on or flashing rapidly. Disconnecting the USB power cable and reconnecting it restores everything to normal for another 8 hours. But then then the Pico locks up again.
Obviously a Meshtastic node that locks up every 8 hours is not much use!
I have 2 other identical nodes that do not have GPS attached and they never lock up.
I have tried:-

  1. A brand new Pico.
  2. Swapping the Waveshare Lora module.
  3. Different versions of the Meshtastic firmware (obviously each modified by Michael to talk to the GPS)
  4. Different USB power supplies.
  5. Different USB cables

Nothing has made any difference. Within plus or minus a few minutes of 8 hours the Pico always locks up.
We (essentially Michael) are still working on the issue but we thought it was time to see if anyone else can contribute usefully.
Ian

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