How to achieve low power in PWM in NCS

[Vignesh R]

Hi
Im using the pwm led example in the connect sdk and tried few changed according to our requirements

The PWM works fine, but the current consumption during the OFF cycle is upto 470uA

Is this an expected behaviour?? Is this because of the clock used for PWM??
When i clear or turn off the PWM, i can able to see 3uA sleep current

There was an example "low-power pwm" only in nrf5SDK, is there any similar example in ncs??
or is there any other way to reduce the power consumption of the PWM led??

Thanks!

[Vidar Berg]

Hello,

The idle current suggests that the HF clock is not being released during idle. Have you disabled logging over UART by building the project with CONFIG_SERIAL=n? If not, the clock will be kept active by the UARTE peripheral.

You may also want to try using the low-power PWM implementation in Zephyr by changing your device tree configuration, as shown in this thread:

SW PWM power consumption  

Best regards,

Vidar

[Vignesh R]

Vidar Berg said:

The idle current suggests that the HF clock is not being released during idle. Have you disabled logging over UART by building the project with CONFIG_SERIAL=n? If not, the clock will be kept active by the UARTE peripheral.

Yes i have done that and also set status = "disabled" in overlay too and able to achieve 3uA when pwm is set to 0 ( pwm is turned off)

Vidar Berg said:

You may also want to try using the low-power PWM implementation in Zephyr by changing your device tree configuration, as shown in this thread:

I have tried this earlier, but coudn't able to achieve PWM's basic functionality(LED was ON always when used this) with this, so i just left it behind
probably i will check into this further

[Vidar Berg]

Vignesh R said:

Yes i have done that and also set status = "disabled" in overlay too and able to achieve 3uA when pwm is set to 0 ( pwm is turned off)

This confirms that you are seeing the PWM active current then. The PWM LED sample runs through various sequences in the run_led_test(), some of which will turn off the PWM, and others that keep it on.

Vignesh R said:

I have tried this earlier, but coudn't able to achieve PWM's basic functionality(LED was ON always when used this) with this, so i just left it behind
probably i will check into this further

I'm not sure what could have caused this. I have not encountered this problem myself. Let me know if you still experience this problem if you try it again.