RE: PPI to SWI/EGU connection

BattleDroid — Fri, 24 Apr 2020 15:21:01 GMT
Thank you this is exactly what I was looking for
RE: PPI to SWI/EGU connection

Vidar Berg — Fri, 24 Apr 2020 09:54:39 GMT
Yes, this is possible. I have put together a simple example if you want to test it out:
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/** @file
 *
 * @defgroup blinky_example_main main.c
 * @{
 * @ingroup blinky_example
 * @brief Blinky Example Application main file.
 *
 * This file contains the source code for a sample application to blink LEDs.
 *
 */

#include <stdbool.h>
#include <stdint.h>
#include "nrf_delay.h"
#include "boards.h"

void SWI0_EGU0_IRQHandler(void)
{
    /* Clear event register */
    NRF_EGU0->EVENTS_TRIGGERED[0] = 0;

    bsp_board_led_invert(BSP_BOARD_LED_0);
}


/* Start LF clock source for RTC */
void clock_init()
{
    NRF_CLOCK->LFCLKSRC = CLOCK_LFCLKSTAT_SRC_Xtal << CLOCK_LFCLKSTAT_SRC_Pos;
    NRF_CLOCK->TASKS_LFCLKSTART = 1;
    while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0);
}
void rtc_init()
{
    NRF_RTC2->CC[0] = 32768;
    /* Event signal must be enabled explicitly unlike most other peripherals */
    NRF_RTC2->EVTENSET = RTC_EVTEN_COMPARE0_Msk;
    NRF_RTC2->TASKS_START = 1;
}
void ppi_interrupt_init()
{
    /* 6 is the default int. priority used in SDK drivers */
    NVIC_SetPriority(SWI0_EGU0_IRQn, 6);
    NVIC_EnableIRQ(SWI0_EGU0_IRQn);

    NRF_EGU0->INTENSET = EGU_INTEN_TRIGGERED0_Msk;

    NRF_PPI->CH[0].EEP = (uint32_t) &NRF_RTC2->EVENTS_COMPARE[0];
    NRF_PPI->CH[0].TEP = (uint32_t) &NRF_EGU0->TASKS_TRIGGER[0];
    /* RTC does not have a SHORT to clear counter on compare match
       so using PPI instead */
    NRF_PPI->FORK[0].TEP = (uint32_t) &NRF_RTC2->TASKS_CLEAR;

    NRF_PPI->CHENSET = PPI_CHENSET_CH0_Msk;
}

/**
 * @brief Function for application main entry.
 */
int main(void)
{
    /* Configure board. */
    bsp_board_init(BSP_INIT_LEDS);

    clock_init();
    rtc_init();
    ppi_interrupt_init();

    /* Wait for interrupts */
    while (true)
    {
       __WFI();
    }
}

/**
 *@}
 **/
The example is configured to toggle a LED from the EGU0 ISR once every second.