pwm_driver period is always 50Hz.WHY?

[DAneill]

Hello all,

I have created a BLE application on nRF52 PCA10040 devboard with S132 SD, in which I would like to use a PWM with the PWM_Driver. My pwm source code as below wants to control an RGB LED on GPIO outputs:

#define TOPVALUE 1000	/* Value up to which the pulse generator counter counts */
static nrf_drv_pwm_t pwm 	= NRF_DRV_PWM_INSTANCE(1);
static nrf_pwm_values_individual_t seq_values_pwm;		/* Duty cycle values */
static nrf_pwm_sequence_t const seq_pwm =				/* Sequence of duty cycle values */
{
	.values.p_individual = &seq_values_pwm,
	.length				 = NRF_PWM_VALUES_LENGTH(seq_values_pwm),
	.repeats			 = 0,
	.end_delay			 = 0
};
void PWM_Init_f(void){

   ret_code_t err_code;

   nrf_drv_pwm_config_t const config_pwm =
   {
	   .output_pins =
	   {
		GPIO_O_PWM_RGB_R | NRF_DRV_PWM_PIN_INVERTED,			/* Channel 0 - RED   */
		GPIO_O_PWM_RGB_G | NRF_DRV_PWM_PIN_INVERTED,			/* Channel 1 - GREEN */
		GPIO_O_PWM_RGB_B | NRF_DRV_PWM_PIN_INVERTED, 			/* Channel 2 - BLUE  */
		GPIO_O_PWM_W     | NRF_DRV_PWM_PIN_INVERTED				/* Channel 3 - WHITE */
	   },
	   .irq_priority = APP_IRQ_PRIORITY_LOW,
       .base_clock   = NRF_PWM_CLK_1MHz,		/* Base Clock */
       .count_mode   = NRF_PWM_MODE_UP,
       .top_value    = TOPVALUE,
       .load_mode    = NRF_PWM_LOAD_INDIVIDUAL,
       .step_mode    = NRF_PWM_STEP_AUTO
   };
   err_code = nrf_drv_pwm_init(&pwm, &config_pwm, NULL);
   APP_ERROR_CHECK(err_code);
   }
void PWM_Update_f(int16_t dutyR, int16_t dutyG, int16_t dutyB, int16_t dutyW)
{
   /* TOPVALUE - : because the LEDs are woring with negative logic */
   seq_values_pwm.channel_0 = TOPVALUE - dutyR;
   seq_values_pwm.channel_1 = TOPVALUE - dutyG;
   seq_values_pwm.channel_2 = TOPVALUE - dutyB;
   seq_values_pwm.channel_3 = TOPVALUE - dutyW;

   nrf_drv_pwm_simple_playback(&pwm, &seq_pwm, 1, NRF_DRV_PWM_FLAG_STOP);
}

And it is triggered in void main() while a button is pressed:

...
PWM_Init_f();
while (true)
{
	sd_app_evt_wait();

	if(nrf_gpio_pin_read(GPIO_I_BUTTON_4) == BUTTON_PRESSED)
	{
		PWM_Update_f(100, 200, 500, 1000);
	}
}

I detect the signals with an oscilloscope on GPIO output, and I always get 50 Hz (20 msec) periods between the edges. Do you know what I did wrong? I would like to have more than 120 Hz period between the edges because of dimming an RGB LED. How is it possible?

Thank you in advance!

Regards,

Daniel

[DAneill]

Hello Sigurd, I changed my code as you suggested, but I still get 50 Hz periods at 1MHz base frequency and 1000 TOPVALUE. By the way before your idea it worked the same way: when I released BUTTON_4, the pwm stopped because of NRF_DRV_PWM_FLAG_STOP. My question is how I can change the periods? Because I tried several base frequencies and TOPVALUEs. When I set 125kHz with 10000 TOPVALUE, the period frequency changed to 10 Hz. I don't really understand this behaviour, but one thing is the most annoying: I cannot go above 50 Hz period, but it would be really necessary for controlling RGB LEDs. I tried the pwm_app also, with that I could use any period frequencies what I wanted. But I want to use the pwm_driver, because it has much more features. And answering to you question: no, I don't use the BSP module in my code.