How to change pwm period on runtime in ncs?

[ilockit_CFR]

Hi, 

I'm trying to play some sounds on a piezo with the help of the pwm. I tried to set the period with pwm_set_dt but only the first call is successful and every subsequent call raised an error. 

Here is my test code:

    for(uint16_t i = 400; i < 800; i++)
    {
        int ret = pwm_set_dt(&piezo_pwm_pos, PWM_HZ(i),
						   PWM_HZ(i) / 2);
        LOG_DBG("pwm_set_dt = %d", ret);

        ret = pwm_set_dt(&piezo_pwm_neg, PWM_HZ(i),
						   PWM_HZ(i) / 2);
        LOG_DBG("pwm_set_dt = %d", ret);
        k_msleep(10);
    }

The results looked like this:

00> D: pwm_set_dt = 0
00> D: pwm_set_dt = 0
00> E: Incompatible period.
00> D: pwm_set_dt = -22
00> E: Incompatible period.
00> D: pwm_set_dt = -22
00> E: Incompatible period.
00> D: pwm_set_dt = -22
00> E: Incompatible period.
00> D: pwm_set_dt = -22
00> E: Incompatible period.
00> D: pwm_set_dt = -22

I didn't find anything in the documentation of pwm_set for the error 22.

How can I change period and pulse while the pwm is running?

Best regards,

Christian

[Sigurd]

Hi!

I see you are getting this in the log: "Incompatible period". Looking at the source code where this is printed, https://github.com/nrfconnect/sdk-zephyr/blob/v3.7.99-ncs1/drivers/pwm/pwm_nrfx.c#L94, there is a comment that explains this error:

 /* If any other channel is driven by the PWM peripheral, the period
* that is currently set cannot be changed, as this would influence
* the output for that channel.
*/