nRF5340DK PWM mess with zephyr

RE: nRF5340DK PWM mess with zephyr

Nicolas Brunner — Thu, 28 Jan 2021 14:30:52 GMT

Thank you.

I tested further and saw that a call to nrf_gpio_cfg_output(0) make the 32k fail on the DK but not on the PDK.

RE: nRF5340DK PWM mess with zephyr

Jørgen Holmefjord — Thu, 28 Jan 2021 12:22:11 GMT

Hi,

It seems that the problem is caused by some incorrect fields in your PWM config. You do not set output_pins[1]-[3], which will set these to 0. This again will connect P0.00 to the PWM peripheral, preventing it from being controlled correctly from other peripherals.

By default, P0.00 is used for the 32.768 kHz LF crystal, which is used by RTC and k_sleep to control the sleep modes.

I verified that both these options resolves the issue:

Set unused pins to NRFX_PWM_PIN_NOT_USED in PWM config:

void pwm_init(void)
{
	nrfx_pwm_config_t config = {
		.irq_priority = PWM_DEFAULT_CONFIG_IRQ_PRIORITY,
		.base_clock   = NRF_PWM_CLK_125kHz,
		.count_mode   = NRF_PWM_MODE_UP,
		.top_value    = PERIOD,
		.load_mode    = NRF_PWM_LOAD_INDIVIDUAL,
		.step_mode    = NRF_PWM_STEP_AUTO,
		.output_pins[0] = LED2_PIN,
		.output_pins[1] = NRFX_PWM_PIN_NOT_USED,
		.output_pins[2] = NRFX_PWM_PIN_NOT_USED,
		.output_pins[3] = NRFX_PWM_PIN_NOT_USED,
    };

    nrfx_err_t err = nrfx_pwm_init(&pwm, &config, NULL, NULL);
    assert(err == NRFX_SUCCESS);

    nrfx_pwm_simple_playback(&pwm, &sequence, 1, NRFX_PWM_FLAG_LOOP);
}

Configure the 32k clock source to use internal RC oscillator, by adding the following configs to prj.conf:
```
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y
```

Best regards,
Jørgen

RE: nRF5340DK PWM mess with zephyr

Nicolas Brunner — Wed, 27 Jan 2021 08:53:21 GMT

Yes, i have the same behavior on my DK.

I have done further testing and if i replace the k_sleep() with "for (volatile uint32_t i = 0; i < 1000000; i++);", both LED blink.

So why does PWM make k_sleep() never exist on a nRF5340DK but work correctly on a nRF5340PDK ?

RE: nRF5340DK PWM mess with zephyr

Jørgen Holmefjord — Tue, 26 Jan 2021 20:20:41 GMT

Hi,

I tested your code on my DK, and it seems like LED1 starts to blink if I comment our pwm_init(). With pwm_init() included, only LED2 blinks. Can you check if this is also true on your board?

Best regards,
Jørgen