RAK3172-T: Does the module include a 32.768 kHz LSE crystal? What is the default MIB_SYSTEM_MAX_RX_ERROR in RUI3?

LPWAN Modules / EVBs RAK3172
1

Hello, i am deploying LoRaWAN sensor for agricultural IoT and we are evaluating the RAK3172-T as a replacemente for de seed wio e5 because it fails to receive the join accept at high spreading factors.

I believe the root cause is that MIB_SYSTEM_MAX_RX_ERROR is too low in the seed AT firmware, making de RX window too narrow. The known fix is LmHandlerSetSystemMaxRxError(200), but this requires reflashing the module bc no AT firmware exposes this parameter.

We are considering RAK3172-T for future projects, bus we need to know:

  1. Does the RAK3172-T module include a 32.768 kHz crystal (LSE) inside the module package? What is the oscillator used for the timing in the opening of the reception windows?

  2. What is the default value of MIB_SYSTEM_MAX_RX_ERROR in the RUI3 firmware?

  3. Can MIB_SYSTEM_MAX_RX_ERROR be changed via AT command or RUI3 Arduino API without reflashing? We know there are commands to change the delay but not the width of the window.

Thanks in advance.

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Welcome to the forum @beavmarin
Just to clarify:

RAK3172-T does not use the SEEED AT firmware, it does use our in house developed RUI3 firmware, unless you flash it with your own custom firmware created with STM32CubeIDE.

The RAK3172-T does use a TCXO, not a simple crystal. The TCXO has 2.5ppm or 0.5ppm accuracy (RAK3172-TE). There is only one oscillator in the module.

There is no MIB_SYSTEM_MAX_RX_ERROR used in RUI3, as our AT command firmware is not based on the examples provided by STM.
You can change the RX windows for both join and “normal” RX timing with AT commands AT+JN1DL/AT+JN2DL and AT+RX1DL/AT+RX2DL

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