PWM control by timer and PPI

Question

Hi all,

I have a problem to activate PWM using a PPI and timer

Attached the code

#define PWM0_GPIOTE_CH      0
#define PWM0_PPI_CH_A       0
#define PWM0_PPI_CH_B       1
#define PWM0_TIMER_CC_NUM   0


void timer_init()
{
    NRF_TIMER3->BITMODE                 = TIMER_BITMODE_BITMODE_24Bit << TIMER_BITMODE_BITMODE_Pos;
    NRF_TIMER3->PRESCALER               = 0;
    NRF_TIMER3->SHORTS                  = TIMER_SHORTS_COMPARE0_CLEAR_Msk << 5;
    NRF_TIMER3->MODE                    = TIMER_MODE_MODE_Timer << TIMER_MODE_MODE_Pos;
    NRF_TIMER3->CC[5] = 125; 
	  NRF_TIMER3->CC[0] = 63; 	
}


void pwm0_init(uint32_t pinselect)
{  
    NRF_GPIOTE->CONFIG[PWM0_GPIOTE_CH] = GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos | 
                                         GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos | 
                                         pinselect << GPIOTE_CONFIG_PSEL_Pos | 
                                         GPIOTE_CONFIG_OUTINIT_High << GPIOTE_CONFIG_OUTINIT_Pos;

    NRF_PPI->CH[PWM0_PPI_CH_A].EEP = (uint32_t)&NRF_TIMER3->EVENTS_COMPARE[0];
    NRF_PPI->CH[PWM0_PPI_CH_A].TEP = (uint32_t)&NRF_GPIOTE->TASKS_CLR[PWM0_GPIOTE_CH];
	 NRF_PPI->CH[PWM0_PPI_CH_B].EEP = (uint32_t)&NRF_TIMER3->EVENTS_COMPARE[5];
	 NRF_PPI->CH[PWM0_PPI_CH_B].TEP = (uint32_t)&NRF_GPIOTE->TASKS_SET[PWM0_GPIOTE_CH];
   
    
    NRF_PPI->CHENSET               = (1 << PWM0_PPI_CH_A) | (1 << PWM0_PPI_CH_B);
}
void mainLoopIteration()
{
	static int i = 0;
	
	
	if (i == 0)
	{		
		timer_init();
		pwm0_init(18);
	
	}
    i++;
	if (i == 20)
	{
		NRF_TIMER3->TASKS_START = 1;

	}

	if (i == 50)
	{

		NRF_TIMER3->TASKS_STOP = 1;
		i = 1;
	}

Doe any one have an idea or advice to help?

Regards,

Amir

Jared · Accepted Answer

Hi 
 Have you seen our example that is featured on our Github on how to use PPI together with PWM here ?

PWM control by timer and PPI

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