RAK3272 - ESP 32 UART

LPWAN Modules / EVBs
1

I connected an ESP32 with a RAK3272 to transmit data sent by another RAK device to my home automation system. The ESP32 powers the RAK3272 at 3.3V.

The UART communication is not very stable: sometimes it works fine, other times no data is transmitted by the RAK3272, and occasionally it sends special characters.

I added a 200µF capacitor across the RAK3272’s power supply and introduced a 2-second delay in the ESP32 program, which helped slightly, but I still experience frequent malfunctions.

Do you have any wiring or setup recommendations for connecting an ESP32 with a RAK3272?

2

There are different reasons why UART is not stable. Some ideas.

  1. How do you connect ESP32 and RAK3272? Is it via jumper wires? Using this approach instead of actual board design sometimes causes the issue - not reliable GND return, loose connections, etc.
  2. If hardware is stable, you can try to lessen the baudrate. If you are using 11520, try 9600. This is not a solution but a possible work around.
  3. Use the latest RUI3 FW.
  4. Check the UART lines using oscilloscope. There can be issues on voltage levels, delay on signals or skew.
3

hello,

The connection between the ESP32 and the RAK3272 is made using jumper wires directly on the PCB. The hardware setup is stable.

At a baud rate of 9600, it works perfectly

Thanks

4

Hi @lolo_b ,

If 9600 baudrate works, it can be that it is related to the UART lines. It will be good if you can check the rise and fall of the signals levels. Btw, are you using the latest FW?