Adding GPS Module to Meshtastic

Hi, I’m new to rak and meshtastic.

I purchased the meshtastic starter kit that comes with a RAK19007 and RAK4631. I downloaded the firmware and used the drag-and-drop method to flash it onto the board. It flashed well and I am able to have two board communicate with each other using the meshtastic app.

What I don’t understand is how to get the gps module (RAK12500) to work. Do I just connect it and it has to work or do I need to flash something else? When I connect it I don’t see any data in the meshtastic app.

I also tried using the arduino IDE to flash for the RAK12500 using the example code in the IDE and was able to get the gps readings on the serial monitor but it seems like it overwrites the flashed meshtastic firmware? Seems like I’m missing some steps.

I’m using Arduino IDE on Windows

Welcome to the forum @cyberjet

Meshtastic firmware should support the RAK12500 automatically.
Flash the “standard” Meshtastic firmware and check the output on USB. It will tell you whether it found the GNSS module or not.

I also have a RAK12500 connected to RAK19007 and RAK4631 but have no idea how to set it up. Under “Position Config” the app asks for GPS Receive GPIO, GPS Transmit GPIO & GPS EN GPIO.
What are these and what should I select? All three drop down boxes show pin 1 to 48.

If you are using the standard Meshtastic firmware you do not have to do anything.

Put RAK12500 into Slot A or Slot D and it is detected.

Log from my RAK4631 with Meshtastic default firmware:
(1) Startup

(2) Search and setup of GPS

It does work with the module in Slot A or Slot D and you using the default firmware for the RAK4631 from Meshtastic Downloads

Thanks Bernd.
At least I know I don’t have to set GPIO pins.

Just another quick question: -

How do you monitor USB on the PC from the RAK4631? Which app do you use?

Any Serial Terminal app will do.
I prefer CoolTerm ( because it is simple to use and has many functions. But there are other options available like Putty, RealTerm, SST, …
Here is an overview:

CoolTerm works fine. Tnx

@beegee Hi Bernd,

I recently got a RAK19007, RAK4631, and RAK12500 modules for Meshtastic applications. Running 2.2.24 firmware, the RAK12500 is in slot A.

The GPS module doesn’t appear to be detected, as there is no mentions of “GPS” in the serial monitor upon device start. Any ideas what the issue can be?


Welcome to the forum @yegor

Try to run the Meshtastic_nRF52_factory_erase_v2.uf2, then flash the Meshtastic firmware again.

The erase firmware is in the ZIP file of the latest Meshtastic firmware.

Thanks for a quick reply. Just did this, no effect. Behavior is the same.

Update: I moved the device to a new location, checked the serial log again and now I see GPS module doing stuff. The only thing that’s different is that I plugged in a lipo battery into the board.

DEBUG | ??:??:?? 0 [Power] Battery: usbPower=1, isCharging=1, batMv=3100, batPct=0
DEBUG | ??:??:?? 0 [GPS] Since no problematic peripherals or interested modules were found, setting power save GPS_EN to pin 34
DEBUG | ??:??:?? 0 [GPS] Probing for GPS at 9600 
INFO  | ??:??:?? 1 [GPS] UBlox Frame Errors using baudrate 9600
DEBUG | ??:??:?? 2 [GPS] Module Info : 
DEBUG | ??:??:?? 2 [GPS] Soft version: ROM CORE 3.01 (107888)
DEBUG | ??:??:?? 2 [GPS] Hard version: 00080000
DEBUG | ??:??:?? 2 [GPS] Extensions:4
DEBUG | ??:??:?? 2 [GPS]   FWVER=SPG 3.01
DEBUG | ??:??:?? 2 [GPS]   PROTVER=18.00
DEBUG | ??:??:?? 2 [GPS]   GPS;GLO;GAL;BDS
DEBUG | ??:??:?? 2 [GPS]   SBAS;IMES;QZSS
DEBUG | ??:??:?? 2 [GPS] Protocol Version:18.00
DEBUG | ??:??:?? 2 [GPS] ProtVer=18
INFO  | ??:??:?? 2 [GPS] GNSS configured for GPS+SBAS+GLONASS+Galileo. Pause for 0.75s before sending next command.
INFO  | ??:??:?? 4 [GPS] GNSS module configuration saved