nrfx_pwm_simple_playback() on nRF9160?

[Jake]

Hi, 

I'm using nRF9160 and want to use PWM with the automatic duty sequence feature using DMA, to make an LED "pulse" for example. 

Looking at the documentation for the registers to control PWM, they seem to be the same on nRF9160 as nRF52, so I have tried to use the nrfx library with the nrfx_pwm_simple_playback() function. Though the library seems to be aimed at nRF52, it is included in zephyr and compiles and runs without crashing just fine on nRF9160. 

GPIO and PWM are working in this project, just the nrfx_pwm_simple_playback() isn't working as expected. The output on the scope is showing an unchanging wave at ~10kHz with a duty of around 95%, I have no idea where this configuration comes from. The output from the pins do not seem to be following the sequence I have configured, and I am wondering if this isn't actually supposed to work, or whether my code is just incorrect. 

Is this library expected to work on nRF9160? If not, is there a similarly easy way to get the right result on nRF9160?

I'm using the 1.0.0 DK with SDK 1.5.0 and modem firmware 1.2.3. I've included some code for review. 

Thank you for your help!

nrfx_pwm_config_t conf = {
    .output_pins   = { 
        leds[0].led_pin,    /*  Extracted from DTS, P0.16 for easy scope probing */
        leds[1].led_pin,    /*  Extracted from DTS, P0.3 */
        leds[2].led_pin,    /*  Extracted from DTS, P0.4 */
        leds[3].led_pin     /*  Extracted from DTS, P0.5 */
     },                                   
    .irq_priority  = NRFX_PWM_DEFAULT_CONFIG_IRQ_PRIORITY,
    .base_clock    = NRF_PWM_CLK_1MHz,                    
    .count_mode    = NRF_PWM_MODE_UP,                     
    .top_value     = 1000,                                
    .load_mode     = NRF_PWM_LOAD_COMMON,                 
    .step_mode     = NRF_PWM_STEP_AUTO,                   
    .skip_gpio_cfg = false 
};

nrfx_pwm_init(&_nrfx_pwm_dev, &conf, unused_dummy_handler, NULL);

static nrf_pwm_values_common_t seq_values[32];
for (uint8_t i = 0; i < 8; i++)
{
    seq_values[i] = (i * 2 + 1) * 62;
    seq_values[15-i] = (i * 2 + 1) * 62;
    seq_values[16+i] = (i * 2 + 1) * 62;
    seq_values[31-i] = (i * 2 + 1) * 62;
}

nrf_pwm_sequence_t seq = { .values.p_common = seq_values, .length = 32, .repeats = 1, .end_delay = 0 };

nrfx_pwm_simple_playback(&_nrfx_pwm_dev, &seq, 1, 0);

[parobin]

Hi,

I try this library with nRF5_SDK16 and the PWM is correctly generated but now I try to use it with Zephyr so I added like Simon said :

IRQ_CONNECT(DT_IRQN(DT_NODELABEL(pwm0)), DT_IRQ(DT_NODELABEL(pwm0), priority),nrfx_isr, nrfx_pwm_0_irq_handler, 0);

All build correctly with no error during initisalization but I have no signal generated... it's the correct way to connect the IRQ_CONNECT ? And in the DT, I have this: 

&pwm0 {

status = "okay";

ch0-pin = <29>;

};

Have you any idea ?

[parobin]

I found the problem. It is the body of the configure_pins function in nrfx_pwm.c which is not executed because two flags have been added which do not allow to process the initialization of gpios by this function (skip_gpio_cfg and skip_psel_cfg). By disabling the conditions related to these two flags, the pwm to drive the leds works correctly.