PWM on nRF52840 GPIO with Zephyr

RE: PWM on nRF52840 GPIO with Zephyr

Håkon Alseth — Tue, 16 Feb 2021 11:40:04 GMT

Hi Bojan,

The zephyr pwm driver API has this restriction, as per its header docs:

https://github.com/nrfconnect/sdk-zephyr/blob/v2.4.99-ncs1-rc1/include/drivers/pwm.h#L155-L158

[quote user="bojan"]Also, where is the place we define the polarity of the PWM signal?[/quote]

bit 0 in the flags you pass is the polarity:

https://github.com/nrfconnect/sdk-zephyr/blob/v2.4.99-ncs1-rc1/include/drivers/pwm.h#L40

Kind regards,

Håkon

RE: PWM on nRF52840 GPIO with Zephyr

bojan — Tue, 16 Feb 2021 10:32:02 GMT

Hello, Hakon...

I still have a hard time to properly use Zephyr PWM driver.

According to some threads (link), in order to stop playing PWM pattern on GPIO, we need to set the pulse width parameter to 0:

pwm_pin_set_usec(pwm_dev, PWM_CHANNEL, period_us, 0)

However, here is what I get on GPIO when I want to stop PWM (Channel D0):

What is the proper way of stop playing PWM pattern on GPIO? Also, where is the place we define the polarity of the PWM signal?

Thanks in advance. Looking forward to reading from you.

Sincerely,

Bojan.

RE: PWM on nRF52840 GPIO with Zephyr

bojan — Tue, 16 Feb 2021 09:02:42 GMT

Thank you!

RE: PWM on nRF52840 GPIO with Zephyr

Håkon Alseth — Mon, 15 Feb 2021 13:28:36 GMT

Hi,

[quote user=""]As I said, PWMs are working only for GPIOs 13, 14, 15, and 16. When I set GPIO 0 for &pwm0, for example, we don't get PWM signal on P0.0 output.[/quote]

If you use the external 32k clock, P0.00 and P0.01 is already in use by the LFCLK. If you do not have or plan to use the external LFCLK, you can switch the source to RC for instance, by setting this configuration:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

Kind regards,

Håkon