some question of nrf51822 timer

[hjjeon]

I am developing using a nrf51822.I need delay timer that can be substitued for nrf_delay_ms(). in other words,need a task delay that can be taken some event from another side during delay time. Is nrf_timer_delay_ms() possible ? If so,please tell me how to use and attention point regarding sw side and hw side. BR

[Tim]

Here's my best guess. Not tested:

#include <nrf51_bitfields.h>
#include <nrf51.h>

#define LFCLK_FREQUENCY           (32768UL)                               /**< LFCLK frequency in Hertz, constant. */

// The attribute constructor ensures this runs before main.
void initClock() __attribute__((constructor));

void initClock()
{
	NRF_CLOCK->LFCLKSRC             = (CLOCK_LFCLKSRC_SRC_Synth << CLOCK_LFCLKSRC_SRC_Pos);
	NRF_CLOCK->EVENTS_LFCLKSTARTED  = 0;
	NRF_CLOCK->TASKS_LFCLKSTART     = 1;
	while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0)
	{
	}
}

/** @brief Function for configuring the RTC with TICK to 100Hz and COMPARE0 to 10 sec.
 */
void sleepDelay(uint32_t ms)
{
	// We use RTC1 since RTC0 is controlled by the soft device.

	// Enable interrupt.
	NVIC_EnableIRQ(RTC1_IRQn);

	// Find the minimum prescalar for this delay.
	//
	// Freq = 32768 Hz / (PRESCALAR + 1)
	//
	// RTC1 has a 24 bit counter.
	//
	// So we want 0xFFFFFF / Freq > ms
	// =>   PRESCALAR > ms * 32768 / 0xFFFFFF - 1
	//
	// PRESCALAR is in the range 0 to 2^12-1.

	NRF_RTC1->PRESCALER     = ms * LFCLK_FREQUENCY / 0xFFFFFFUL;
	NRF_RTC1->CC[0]         = ms * LFCLK_FREQUENCY / (NRF_RTC1->PRESCALER + 1);

	// Enable COMPARE0 event and COMPARE0 interrupt:
	NRF_RTC1->EVTENSET      = RTC_EVTENSET_COMPARE0_Msk;
	NRF_RTC1->INTENSET      = RTC_INTENSET_COMPARE0_Msk;

	NRF_RTC1->TASKS_CLEAR = 1;
	NRF_RTC1->TASKS_START = 1;

	// Wait For Event.
	// This wakes up when any interrupt is fired so it is possible that the delay will not be as long as requested.
	__WFE();
}

/** @brief: Function for handling the RTC0 interrupts.
 * Triggered on TICK and COMPARE0 match.
 */
void RTC1_IRQHandler()
{
	if ((NRF_RTC1->EVENTS_COMPARE[0] != 0) && ((NRF_RTC1->INTENSET & RTC_INTENSET_COMPARE0_Msk) != 0))
	{
		NRF_RTC1->EVENTS_COMPARE[0] = 0;
		NRF_RTC1->INTENSET = 0;
		NRF_RTC1->TASKS_STOP = 1;
	}
}