Question about high resolution timer

RE: Question about high resolution timer

Susheel Nuguru — Thu, 16 Apr 2015 11:00:18 GMT

Great it helped, I have converted that comment into an answer. Can you please accept the answer by clicking the "✓" of the acceptable answer. so that we can close the case

RE: Question about high resolution timer

Stanley — Wed, 15 Apr 2015 17:35:32 GMT

Thanks Aryan, you're right, I didn't clear timer in interrupt handler, I had thought the counter will be cleared automatically in TIMER mode, it's my fault. It will be much better if you can give more information in your reference manual, and update the sample code for timer.

Anyway, this timer can meet my request completely. Thanks again!

Regards, Stanley

RE: Question about high resolution timer

Stanley — Wed, 15 Apr 2015 17:21:50 GMT

Hi Aryan,

Yes, I'm using S110 as the BLE stack.

RE: Question about high resolution timer

Susheel Nuguru — Wed, 15 Apr 2015 08:26:34 GMT

you did not mention if you are using softdevice or not?

RE: Question about high resolution timer

Susheel Nuguru — Wed, 15 Apr 2015 08:12:42 GMT

I am not sure why you are getting same timeout. Did you clear the counter everytime you get the TICK? otherwise it will go round the counter overflow everytime and it won't matter what you put in CC registers, you need to have below line when you initialize your timer

NRF_TIMER2->SHORTS      = 1 << TIMER_SHORTS_COMPARE0_CLEAR_Pos;

RE: Question about high resolution timer

Susheel Nuguru — Wed, 15 Apr 2015 07:27:51 GMT

Are you using softdevice for your application? If you are using and if you have NRF_APP_PRIORITY_HIGH, with 5ms tick it might be interfering with softdevice. I will verify to see how low I can go with the RTC1 tick when using softdevice and reply later.

RE: Question about high resolution timer

Stanley — Wed, 15 Apr 2015 07:20:45 GMT

Thanks Aryan for the feedback.

Could you help confirm: 1) what the minimum timer interval of app_timer is? 2) why I can't get exact timeout with the settings in my test codes? something wrong with it?

RE: Question about high resolution timer

Susheel Nuguru — Wed, 15 Apr 2015 07:09:39 GMT

Hi Stanley,

Timer1 and Timer2 only support 16bit and these are the only timers accessable by applications when using softdevice.

Only Timer0 has 32/24/16 bit mode and its access is restricted when using the softdevice. For details on which bitmodes are supporting which timers see the device product specification.

Timer0 can be used by apps in a restricted way when using Multiprotocol Timeslot API

RE: Question about high resolution timer

Stanley — Wed, 15 Apr 2015 06:46:47 GMT

With more tests, I tried to set different value for CC[0] directly, (Interrupt on CC[1] is disabled), and with below interrupt handler, looks like I got same timeout interval:

void TIMER2_IRQHandler(void)
{
        if ((NRF_TIMER2->EVENTS_COMPARE[0] != 0) && ((NRF_TIMER2->INTENSET & TIMER_INTENSET_COMPARE0_Msk) != 0)) {
                static int count = 0;
                count++;
                NRF_TIMER2->EVENTS_COMPARE[0] = 0;           //Clear compare register 0 event   
                if (count % 10 == 0) {
                        printf("%d\r\n", count);
                        nrf_gpio_pin_toggle(GPIO_TOGGLE_PIN);           //Set LED
                }
        }
}

Could anyone help me on this question? Any feedback will be really appreciated.

Thanks & Regards, Stanley