PWM moves the specified number of steps in nRF52832

[chianglin]

Hi,

I am try to create a PWM output which can move the specified number of steps.

Please find following source code

uint32_t		TotalMove = 0;
void pwm0_Manual_handler(nrf_drv_pwm_evt_type_t event_type)
{
	#define	StepCntInitial		2
	static	uint32_t		StepCnt = 0/*MotorInitializeStep*/;
	static	uint8_t			DebugPrint = 0;

	TotalMove++;
	if ( StepCnt-- == 0 )
	{
		StepCnt = StepCntInitial;
		nrf_drv_pwm_stop(&m_pwm0, true);
	}
	return;
}

void PwmInit_ManualRun(void)
{
	{	// Control PWM-0
		nrf_drv_pwm_config_t const config =
		{
		    .output_pins =
		    {
		        PwmOutputPin | NRF_DRV_PWM_PIN_INVERTED,
		        2 | NRF_DRV_PWM_PIN_NOT_USED,
		        30 | NRF_DRV_PWM_PIN_NOT_USED,
		        28 | NRF_DRV_PWM_PIN_NOT_USED
		    },
		    .irq_priority = APP_IRQ_PRIORITY_LOWEST,
		    .base_clock   = NRF_PWM_CLK_16MHz,
		    .count_mode   = NRF_PWM_MODE_UP,
		    .top_value    = m_BaseFrequency,
		    .load_mode    = NRF_PWM_LOAD_INDIVIDUAL,
		    .step_mode    = NRF_PWM_STEP_AUTO
		};
		APP_ERROR_CHECK(nrf_drv_pwm_init(&m_pwm0, &config, pwm0_Manual_handler));
		
		m_pwm0_set_value.channel_0 = m_BaseFrequency/2;
		m_pwm0_set_value.channel_1 = m_BaseFrequency/2;
		m_pwm0_set_value.channel_2 = m_BaseFrequency/2;
		m_pwm0_set_value.channel_3 = m_BaseFrequency/2;
		
		(void)nrf_drv_pwm_simple_playback(&m_pwm0, &m_pwm0_seq, 1, NRF_DRV_PWM_FLAG_LOOP);
		NRF_LOG_INFO("Use call-back: pwm0_Manual_handler");
	}
}

After I execute above problem, I can get following wave form output.

First image is correct, and the second image is incorrect.

The second image include to many wave, but I only want send 2 waves output.

Would you please tell me how to fix this problem?

Thank you

[Simonr]

Hi

Can you clarify one thing for me. Are you getting the correct amount of steps sometimes, and sometimes not. Or are you always getting the wrong output?

Also, have you tride setting your StepCntInitial to for example 1, to see how many steps 1 of these step counts provide?

Best regards,

Simon

[chianglin]

Hi Simon,

Yes, the output wave-form some times is correct, some times is wrong, but I don't know its rule.

By the way, how can I set StepCntInitial parameter?

Best Regards,

Chianglin