Writing data to Central (BLEserial example) at set interval with timer.

[DhirajGehlot]

Hello Everyone,

I am using nrf51822, S130 SDK11 with arduino 1.8.1. Currently I am trying to write data (battery data) and toggle led at set interval using timer 2. I am using BLESerial example code to write data. When the timer times out, the BLE kind of crashes and doesn't respond However, if I disable "BLESerial.write(data);" , the led toggles properly and program runs correctly. Somehow, the BLESerial call is causing problem. Is it something that BLESerial function calls and TIMER2 are inter-related? I checked the product specification which mentions TIMER0 is used by softdevice and there is no dependency on TIMER2. Can someone help me out for this issue?

Timer code:
void ms_timer_init(void)
{

    NRF_TIMER2->TASKS_STOP        = 1;                       // Stop timer, if it was running
    NRF_TIMER2->TASKS_CLEAR       = 1;
    NRF_TIMER2->MODE              = TIMER_MODE_MODE_Timer;   // Timer mode (not counter)
    NRF_TIMER2->EVENTS_COMPARE[0] = 0;                       // clean up possible old events
    NRF_TIMER2->EVENTS_COMPARE[1] = 0;
    NRF_TIMER2->EVENTS_COMPARE[2] = 0;
    NRF_TIMER2->EVENTS_COMPARE[3] = 0;

    // Timer is polled, but enable the compare0 interrupt in order to wakeup from CPU sleep
    NRF_TIMER2->INTENSET    = TIMER_INTENSET_COMPARE0_Msk;
    NRF_TIMER2->SHORTS      = 1 << TIMER_SHORTS_COMPARE0_CLEAR_Pos;    // Clear the count every time timer reaches the CCREG0 count
    NRF_TIMER2->PRESCALER   = 9;                                       // Input clock is 16MHz, timer clock = 2 ^ prescale -> interval 1us
    NRF_TIMER2->CC[0]       = 32;                          // 625uS with 1MHz clock to the timer
    NVIC_EnableIRQ(TIMER2_IRQn);
    NRF_TIMER2->TASKS_START = 1;
}

// Start the timer - it will be running continuously}
/** TIMTER2 peripheral interrupt handler. This interrupt handler is called whenever there it a TIMER2 interrupt*/

void TIMER2_IRQHandler(void)
{
  if ((NRF_TIMER2->EVENTS_COMPARE[0] != 0) && ((NRF_TIMER2->INTENSET & TIMER_INTENSET_COMPARE0_Msk) != 0))
  { 
    NRF_TIMER2->EVENTS_COMPARE[0] = 0;         //Clear compare register 0 event
    BLESerial.write(data);
    digitalWrite(LED, !(digitalRead(LED)));
  }
}

[Slowspark]

Welcome, i have similar problem. Timer1 and Timer2 works together to measure frequency, but when i want send data via BLESerial.write(data) counter stop. Any solution for this? Regards

[DhirajGehlot]

Hello,

I got solution to this problem. The issue is cased by running BLE functions from a high priority interrupt. When using a BLE stack such as the S130 SoftDevice interrupt priorities 0 and 2 are reserved for the SoftDevice, and should not be used by the application. Set the interrupt priority of the TIMER2 interrupt to 3, and it should work better: NVIC_SetPriority(TIMER2_IRQn, 3);