B-WL5M-SUBG1 (STM32WL5MOC) current consumption too high

[JBive.1]

Hello,

We have an issue with the B-WL5M-SUBG1 evaluation board: The idle current consumption is higher than expected: 89 uA (vs. expected: 1-2 uA) after joining (OTAA) successfully.

• Board: B-WL5M-SUBG1
• Firmware: STM32CubeWL/Projects/B-WL5M-SUBG1/Applications/LoRaWAN/LoRaWAN_AT_Slave and STM32CubeWL/Projects/B-WL5M-SUBG1/Applications/LoRaWAN/LoRaWAN_End_Node
• Firmware version: STM32CubeWL V1.3.0 (latest from https://github.com/STMicroelectronics/STM32CubeWL)
• Power supply: 5 V via USB-C adapter board
• Current measurement: STM32WL5MOC, not including sensors, measured at IDD jumper (JP2) using Joulescope

Do you have an idea what could be the issue?

Thanks!

[STTwo-32]

Could you please add the details of the configurations that you are doing.

Best Regards.

STTwo-32

[JBive.1]

Hi, steps to reproduce the issue:

• Firmware: Clone from https://github.com/STMicroelectronics/STM32CubeWL, import project "LoRaWAN_AT_Slave" into STM32CubeIDE, compile "Debug" using STM32CubeIDE.
• Connect debugger (STLINK-V3PWR) to board (B-WL5M-SUBG1), flash firmware to STM32WL5MOC.
• Command to LoRaWAN_AT_Slave application: AT+JOIN=1 (OTAA join).
• Wait until it has joined.
• Measure current consumption of the board over jumper JP2 (IDD) -> 89 uA.
• Same current consumption has been measured with the application "LoRaWAN_End_Node" (change in file sys_conf.h: SENSOR_ENABLED = 0).

Thanks!

[alexemdesgagne · Accepted solution]

Hi,
To resolve this issue, we pull the UART TX and RX pins high.

Maybe that could help you.

Alexandre

[JBive.1]

Hello Alexandre,

Thank you very much for your hint, you nailed it!

We changed two things:

• Pull-up on UART RX (PA3)
• Pull-down on JTDI (PA15)

This way, the idle current consumption went down to 1.9 uA! We are very happy with this.

Details:

Projects/B-WL5M-SUBG1/Applications/LoRaWAN/LoRaWAN_AT_Slave/Core/Src/usart.c: change:

    GPIO_InitStruct.Pin = USARTx_RX_Pin|USARTx_TX_Pin;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_PULLUP; // <-- changed
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF8_LPUART1;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

Projects/B-WL5M-SUBG1/Applications/LoRaWAN/LoRaWAN_AT_Slave/Core/Src/gpio.c: add in function MX_GPIO_Init():

  /* Configure GPIO pin : JTDI */
  GPIO_InitStruct.Pin = GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLDOWN;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

The same changes can be applied to Projects/B-WL5M-SUBG1/Applications/LoRaWAN/LoRaWAN_End_Node as well.

Thanks again!

[alexemdesgagne]

Excellent!

Happy to hear this news!

Alexandre

[Prasadh_004]

Hello there,

Did you use any specfic sleep modes to achieve this or just the above mentioned steps kindly let me know of the configurations and references you have used for achieveing this, I am planning on a low power use case for that chip too.

Thanks in Advance!
Regards,
Prasadh

[JBive.1]

Hello Prasadh,

We used the above mentioned steps, nothing more. Does this answer your question?

BR
Jonas