BLE_HeartRate application consumes more power on STM32WB5MMG than expected

[JHCarter]

I have tried running the BLE_HeartRate application as generated by STM32CubeIDE v1.11.0 which used WB FV 1.15.0. I am running on a custom board (DK board is not available right now) that has a STM32WB5MMG module, the recommended capacitors, and a header for connecting an STLINK-V3MINI, and nothing else.

By default CFG_LPM_SUPPORTED was set to 0, CFG_DEBUGGER_SUPPORTED and CFG_DEBUG_APP_TRACE were set to 1, This setup draws about 13mA.

When I change CFG_LPM_SUPPORTED to 1, CFG_DEBUGGER_SUPPORTED and CFG_DEBUG_APP_TRACE to 0, I see a current draw of 8.7mA. This is far more than I would expect.

In contrast, using the same tools I generated and ran the same application on a Nucleo-WB15CC board and I see a current draw around 400uA in low power mode.

I understand that the BLE_HeartRate application is the recommended low-power demonstration. Is anyone running it on a STM32WB5MM-DK board? Are you seeing similar results?

Can anyone suggest how to reduce the power consumption on this setup?

[JHCarter]

I have modified my test setup for the Nucleo-WB15CC board to remove all jumpers from JP5 to isolate the onboard STLINK. This brings the current draw between advertisements down to 1uA.

The custom board with the STM32WB5MMG module is connected to the STLINK-V3MINI only for programming. The STLINK is disconnected during testing so the whopping 8.7mA current draw remains the same.

[Remy ISSALYS]

Hello,

You should have the same power consumption than on STM32WB55, maybe you have an extra consumption from a peripheral on your custom board. Can you share your schematic?

Best Regards

[JHCarter]

Here is the schematic. R2, R3, and IC1 are not populated, so there are no peripherals on the board. Nothing is connected to J2 or J3 during the test.

Thanks.

[Remy ISSALYS]

Hello,

Can you try with the BLE_HeartRate reference binary?

Best Regards,

[JHCarter]

I tried the BLE_HeartRate reference binary and the results are better but nowhere near as good as with the Nucleo-WB15CC board.

When it starts up it is drawing about 420uA. After one minute the application increases the advertising interval to around 2 seconds and I can see a current draw of about 156uA in between advertisements. I see the expected behavior when I connect to the board with the Android ST BLE ToolBox app.

I also compiled the BLE_HeartRate app for the P-NUCLEO-WB55-NUCLEO board, loaded the result on my custom board, and get the same results.

As noted above I get a current draw that is two orders of magnitude better on the Nucleo-WB15CC board.

Thanks for your help.

[Remy ISSALYS]

Hello,

The extra power consumption may be due to the pull up on PH3-BOOT0 pin.

Best Regards

[JHCarter]

You are correct. I tied PH3-BOOT0 to ground through a 10K resistor and the current draw between advertisements dropped from 160uA to 3uA.

Many thanks for your help.