RAK4200 Floating Pins During Sleep

Putting RAK4200 into sleep doesn’t get the module into the sleep current as advertised.
It is around 40 uA. Upon checking all the pins on RAK4200 during sleep, I notice the following pins are floating during sleep:

  • 3 - UART2_DE
  • 4 - UART1_TX
  • 6 - UART1_DE
  • 9 - I2C_SCL
  • 10 - I2C_SDA
  • 16 - SPI_MISO

But, the biggest culprit among them is pin 16 (SPI_MISO). If I were to put a multimeter to measure the voltage of this pin 16, the extra 40 uA will disappear. Firmware revision is v3.0.12.

Hi @phangmoh, How do you test the module current? Separate module test, or module + your circuit board test?

Hi @Sucre, module + board. Prior to this, RAK4200 was not mounted to ensure nothing is wrong with circuits. Base board current is 7 uA. Adding the RAK4200 shoot up to more than 50 uA. Those RAK4200 pins (3, 4, 6, 9, 10, 16) I mentioned are not connected to anything on the board as they are not needed. The fact that they have voltages other than GND and 3.3V, it means they are floating.