RAK3272S not working


I’m trying to get a RAK3272S to work. I have hooked it up to 3.3V of a bench power supply. The UART is connected to a FTDI TTL-232R-RPi.

The module doesn’t take any current. Also double-checked with a Fluke Multimeter. Is this normal? Also, sending it AT commands via RAK SERIAL PORT TOOL doesn’t do anything.

I have also tried to pull BOOT0 to high/low. Doesn’t change anything to the current.

The same applies to the RST Pin.

Do I have a wiring issue? Or did I maybe receive a faulty module?

Ok, my fault. Got it now working.

  • The Baudrate is 9600 and not 115200.
  • The AT Command interface is just on UART2. UART1 seems to not transmit anything on the firmware v1.0.4 which is preloaded to this module.
  • Disconnecting the module from Power won’t reset it. It needs so little current that it can power itself from capacitors for multiple seconds.
  • Use picocom with --omap crcrlf flag.

Welcome to RAK forum @spinach .

It seems your module has the legacy firmware 1.0.4. If ever you will switch to RUI3, the baud rate will be now 115200. It is not really intuitive but AT CMDs and FW update is done in UART2 and not UART1. LPUART feature of STM32WL chip is on UART2 only.