STM32WBDK LPM wont allow PWM to work

nayeemcron · ‎2025-06-24

I’m driving a hobby servo on the STM32WB5MM-DK Discovery board using TIM2 PWM and the STM32CubeWB Sequencer/LPM utilities. When I disable low-power mode entirely, the servo moves flawlessly on each 500 ms button-hold toggle. But as soon as I allow the LPM manager to enter Stop mode, the PWM pulses become unstable and the servo either jitters or stops moving.

PWM in Stop Mode: Are there proven techniques to retain stable PWM outputs during Stop or Low-Power Run modes on STM32WB series?

Sequencer Integration: Can anyone share examples of driving servos reliably while staying in LPM using the Utility Sequencer?

I have uploaded the project.

FilipKremen · ‎2025-06-24

Hello,

if you want to generate a PWM signal in LP mode, you could use a LP timer.

Please kindly read section 27 in RM.

Multiprotocol wireless 32-bit MCU Arm®-based Cortex®-M4 with FPU, Bluetooth® Low-Energy and 802.15.4 radio solution - Reference manual

If you have any other question, please let me know.

Best regards,

Filip Kremen

nayeemcron · ‎2025-06-25

I was expecting to have better control over the application as in not enter low power mode before the button event is set. Could you please have a look at my application code and suggest me a way to do so.

FilipKremen · ‎2025-06-25

Hello,

I have quickly checked your project, can you please try to move UTIL_LPM_SetStopMode(1U << CFG_LPM_APP, UTIL_LPM_ENABLE) function at the end of PWM_timer_ISR()? This will enable stop mode after stopping the PWM signal.

Best regards,

Filip Kremen