Using nrfx drivers with Zephyr device tree

[grzegorz]

I'd like to use playback feature of PWM. There is NRFX function for that: nrfx_pwm_complex_playback(). This function, like other NRFX drivers, needs appropriate instance structure, here it's nrfx_pwm_t. The instance variable can be created with NRFX_PWM_INSTANCE. But now we have NCS and device trees. I already have PWM in device tree and I use it with functions such as pwm_set_dt(). How can I use nrfx_pwm_complex_playback() now? I don't see any way to initialize nrfx_pwm_t variable using pwm_dt_spec variable. Should I use NCS device tree and old NRFX device instance at the same time? It would give messy code.

[Sigurd]

Hi!

If the Zephyr PWM driver does not fulfill your use-case, you would instead have to use the nrfx driver. 

See this example on how to use it in a NCS/Zephyr context:

https://github.com/zephyrproject-rtos/hal_nordic/blob/master/nrfx/samples/src/nrfx_pwm/grouped_mode/main.c

[grzegorz]

Hi!

Yes, I know I can use the nrfx driver and I have seen this example. My concern is the coexistence of device tree and nrfx. For example I have the PWM pin configured in device tree. With nrfx I need to configure it second time with NRFX_PWM_DEFAULT_CONFIG() macro. It's not flexible and can lead to mistakes. So I'm looking for a way in which nrfx driver could use config from device tree. This is what I came up with:

static const struct pwm_dt_spec buzzer = PWM_DT_SPEC_GET(DT_NODELABEL(buzzer_pwm));

const nrfx_pwm_t *pwm = buzzer.dev->config;
const int PLAYBACK_COUNT = 1;
nrf_pwm_sequence_t seq[2]; //not initialized, but this is just an example
nrfx_pwm_t instance;
instance.p_reg = pwm->p_reg;
nrfx_pwm_complex_playback(&instance, &seq[0], &seq[1], PLAYBACK_COUNT, NRFX_PWM_FLAG_LOOP);