PWM during sleep mode

[DamienB]

Hello,

I am using the module nRF52840 and nRF SDK 15.2.0. I would like to start a PWM, going to sleep mode and still having the pwm running.

I tried combining the pwr_mgmt example and pwm_library example but when i enter in shutdown mode, the PWM stops.

1. Is there a way to achieve this ?

2. Maybe another sleep mode allow this instead of the shutdown mode ? 

3. Do you have any idea concerning current consumption when the device is using PWM ?

4. What would be the gain of Low-Power PWM (low_pwr_pwm example) ?

[Vidar Berg]

Hello,

1. It's not possible to run the PWM in System OFF mode. All clock sources are powered down in this mode. However, the CPU will automatically enter System ON idle mode as long as you call the __WFE (or sd_app_evt_wait() if softdevice is enabled) from your main loop. This will result in the lowest possible current consumption with PWM enabled. 

2. Yes, System ON mode

3. Around 500-1000 uA depending on frequency and load

4. Significantly lower current consumption, but with lower accuracy and max. frequency.