PWM via EasyDMA

[Rm3]

Hello,

Following the NRF54L Express course I see that PWM duty cycle can be updated from RAM via EasyDMA but I can't see an example of how this can be done anywhere or how to even start.

Unfortunately I'm quite new to the connect SDK, does anyone have an example of this being done that I could take a look at?

Thank you

[Priyanka]

Hi,

Please take a look at the code snippets mentioned in this documentation:

https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/pwm.html#ariaid-title2 

From the code snippets,

pwm_seq is an array in RAM holding the duty cycle values for each channel.
The .PTR register points to this array, and .MAXCNT sets the number of values to transfer.
The DECODER register is set to load individual values for each channel.
The TASKS_DMA.SEQ[0].START task triggers EasyDMA to start transferring the values from RAM to the PWM peripheral, updating the duty cycle accordingly.

-Priyanka

[Rm3]

Thank you Priyanka, that is very helpful.

Is it possible to query the current duty cycle somehow/know how far into pwm_seq the pwm has got?

Many thanks.

[Priyanka]

I don't think there is any "direct" register for this, but maybe you can check the following registers:

They tell you the number of bytes after a sequence completion and how many bytes from your RAM buffer have been read so far during the ongoing sequence respectively.

You can also track the following registers:

-Priyanka