Using timer how to make 5 sec delay in pca10040 board?

[naveen]

Hi,

I am using pca10040 board. i need to toggle a led in 5sec once. I tried to change the prescale value. But im not able to get that much time delay.

Can any one help me on this?

[Ole Bauck]

Have you tried using app_timer? It uses the RTC which will give you overflow at 512 seconds with prescaler 0. The RTC is also much more power efficient than using TIMER. See here for a tutorial on how to use it. You can also use the RTC directly, but be aware that RTC0 is used by SoftDevice and RTC1 is used by app_timer.

[Ole Bauck]

BTW you can use TIMER to get 5 second delay. Using prescaler 9 and 32 bits the overflow value will be 2^32 / 16MHz * 2^9 = 137439 seconds.

[naveen]

Hi Ole Bauck,

Thank you for your valuable answers. Now i can able to do time delay whatever i need.

[naveen]

Hi Ole Bauck,

If i set prescale value 9 and bitmode is 32 means. The counting will be start in 0 to 4,294,967,296. For 5 second delay i set cc[0]=156250. For my requirement i need continuously toggle a led for 5 mins. At very first time its coming in 5 second [0 - 156250] but after that its taking more time [156270 - 4,294,967,296] I dont kw how to do that..

can u guide me on thz.. below is my function:

void start_timer(void)
{
        NRF_TIMER2->MODE = TIMER_MODE_MODE_Timer;
        NRF_TIMER2->TASKS_CLEAR = 1;
        NRF_TIMER2->PRESCALER = 9;
        NRF_TIMER2->BITMODE = TIMER_BITMODE_BITMODE_32Bit;
        NRF_TIMER2->CC[0] = 156250;
        NRF_TIMER2->INTENSET = (TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos) ;
        NVIC_EnableIRQ(TIMER2_IRQn);
        NRF_TIMER2->TASKS_START = 1;
}

void TIMER2_IRQHandler(void)
{
        if ((NRF_TIMER2->EVENTS_COMPARE[0] != 0))
        {
                NRF_TIMER2->EVENTS_COMPARE[0] = 0;                                      
                NRF_TIMER2->CC[0] += 156250;
                nrf_gpio_pin_toggle(GPIO_TOGGLE_PIN);
        }
}

[Ole Bauck]

You can use shorts:

NRF_TIMER2->SHORTS = (TIMER_SHORTS_COMPARE0_CLEAR_Enabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos);

This will clear the timer counter value on CC[0] compare. If not doing this the timer will count to the maximum value before it overflows.