Demand: nRF52 Timer operate in 400ns. nRF52 Timer Interrupt response time is too slow!

RE: Demand: nRF52 Timer operate in 400ns. nRF52 Timer Interrupt response time is too slow!

Austin (S.F.) — Sat, 23 May 2020 03:57:20 GMT

Hi Edvin

Thanks you reply.

I try to make timer as fast as possible, but it's failed.

I toggle the pin to check the interrupt timing cost. I found interrupt timing cost is around 730ns ~ 1us.

--------------------------------------

I will try your suggestion, the PPI and GPIOTE.

Could you tell me how to use PPI to setup a pin to be input mode?

Austin

RE: Demand: nRF52 Timer operate in 400ns. nRF52 Timer Interrupt response time is too slow!

Edvin — Fri, 22 May 2020 14:05:16 GMT

Hello,

I don't understand. You set up the timer, but you toggle the pin both from your main loop and in your timeout interrupt?

If the timer is too fast, you should look into the PPI (programmable peripheral interface). Check out the example found in SDK\examples\peripheral\ppi

This example doesn't toggle a pin, but writes some information in the log. Monitor the UART log.

But you can change this example to set the PPI task to toggle the pin. It is a bit complex. You need to use nrf_drv_gpiote_set_task_addr_get instead of nrf_drv_timer_task_address_get in nrf_drv_timer_task_address_get().

BR,

Edvin

RE: Demand: nRF52 Timer operate in 400ns. nRF52 Timer Interrupt response time is too slow!

Austin (S.F.) — Thu, 21 May 2020 09:45:14 GMT

#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "nrf_drv_timer.h"
#include "bsp.h"
#include "app_error.h"

const nrf_drv_timer_t TIMER_LED = NRF_DRV_TIMER_INSTANCE(0);

#define TEST_OUT1	12

/**
 * @brief Handler for timer events.
 */
void timer_led_event_handler(nrf_timer_event_t event_type, void* p_context)
{
		nrf_gpio_pin_write (TEST_OUT1, 1);
		NRF_TIMER0->EVENTS_COMPARE[0] = 0;	
}


/**
 * @brief Function for main application entry.
 */
int main(void)
{
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_HFCLKSTART = 1;
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
	
	nrf_gpio_cfg_output (TEST_OUT1);									//SETUP TEST P1 = OUTPUT	
	
  NRF_TIMER0->TASKS_STOP = 1;	// Stop timer
  NRF_TIMER0->MODE = TIMER_MODE_MODE_Timer;  // taken from Nordic dev zone
  NRF_TIMER0->BITMODE = (TIMER_BITMODE_BITMODE_08Bit << TIMER_BITMODE_BITMODE_Pos);
  NRF_TIMER0->PRESCALER = 0;	// 1us resolution
  NRF_TIMER0->TASKS_CLEAR = 1; // Clear timer
  NRF_TIMER0->CC[0] = 200;					//375ns 
  NRF_TIMER0->INTENSET = TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos;  // taken from Nordic dev zone
  NRF_TIMER0->SHORTS = (TIMER_SHORTS_COMPARE0_CLEAR_Enabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos);
	_NRFX_IRQ_PRIORITY_SET(TIMER0_IRQn,1);
	NVIC_EnableIRQ(TIMER0_IRQn);
  NRF_TIMER0->TASKS_START = 1;	// Start TIMER

    while (1)
    {
		nrf_gpio_pin_write (TEST_OUT1, 0);
    }
}

/** @} */

void timer_led_event_handler(void);

#if NRFX_CHECK(NRFX_TIMER0_ENABLED)
void nrfx_timer_0_irq_handler(void)
{
	timer_led_event_handler();
//    irq_handler(NRF_TIMER0, &m_cb[NRFX_TIMER0_INST_IDX],
//        NRF_TIMER_CC_CHANNEL_COUNT(0));
}
#endif

Modify SDK16 example Timer

RE: Demand: nRF52 Timer operate in 400ns. nRF52 Timer Interrupt response time is too slow!

awneil — Thu, 21 May 2020 09:15:17 GMT