Not able to setup timer interrupt in nRF51822

Question

Timer_interrupt.txt 
 Hi all, can anyone please help me in setup up the timer interrupt? I could only see the printing of "Entered 2". Kindly check on the attached text file for my code. Kindly assist. Thanks in advance.

monpetit · Accepted Answer

Arduino source code is compiled as C++, but IRQ Handler is linked as C. So you have to declare void TIMER1_IRQHandler(void) with C linkage. #include #ifdef __cplusplus extern "C" { #endif void TIMER1_IRQHandler(void); #ifdef __cplusplus } #endif // count to us (micro seconds) conversion factor // set in start_timer() static volatile float countToUs = 1; // counter static volatile uint32_t tCount = 0; // set up and start Timer1 void start_timer(void) { NRF_TIMER1->MODE = TIMER_MODE_MODE_Timer; NRF_TIMER1->TASKS_CLEAR = 1; // set prescalar n // f = 16 MHz / 2^(n) uint8_t prescaler = 0; NRF_TIMER1->PRESCALER = prescaler; NRF_TIMER1->BITMODE = TIMER_BITMODE_BITMODE_16Bit; // 16 MHz clock generates timer tick every 1/(16000000) s = 62.5 nano s // With compare enabled, the interrupt is fired every: 62.5 * comp1 nano s // = 0.0625*comp1 micro seconds // multiply this by 2^(prescalar) uint16_t comp1 = 500; // set compare NRF_TIMER1->CC[1] = comp1; // set conversion factor countToUs = 0.0625 * comp1 * (1 << prescaler); //printf("timer tick = %f us ", countToUs); // enable compare 1 NRF_TIMER1->INTENSET = (TIMER_INTENSET_COMPARE1_Enabled << TIMER_INTENSET_COMPARE1_Pos); // use the shorts register to clear compare 1 NRF_TIMER1->SHORTS = (TIMER_SHORTS_COMPARE1_CLEAR_Enabled << TIMER_SHORTS_COMPARE1_CLEAR_Pos); // enable IRQ NVIC_EnableIRQ(TIMER1_IRQn); Serial.println("Entered 2"); // start timer NRF_TIMER1->TASKS_START = 1; } // Timer 1 IRQ handler // just increment count void TIMER1_IRQHandler(void) { Serial.println("Entered 3"); if (NRF_TIMER1->EVENTS_COMPARE[1] && NRF_TIMER1->INTENSET & TIMER_INTENSET_COMPARE1_Msk) { // clear compare register event NRF_TIMER1->EVENTS_COMPARE[1] = 0; // increment count tCount++; } } void setup() { // put your setup code here, to run once: Serial.begin(9600); delay(2000); start_timer(); } void loop() { // put your main code here, to run repeatedly: Serial.println("Entered 1"); } Good Luck! :) New code: #include // count to us (micro seconds) conversion factor // set in start_timer() static volatile float countToUs = 1; // counter static volatile uint32_t tCount = 0; #ifdef __cplusplus extern "C" { #endif void TIMER1_IRQHandler(void); #ifdef __cplusplus } #endif // Timer 1 IRQ handler // just increment count void TIMER1_IRQHandler(void) { if (NRF_TIMER1->EVENTS_COMPARE[1] && NRF_TIMER1->INTENSET & TIMER_INTENSET_COMPARE1_Msk) { // clear compare register event NRF_TIMER1->EVENTS_COMPARE[1] = 0; // increment count tCount++; if ((tCount % 300) == 0) Serial.println("Entered 3"); } } // set up and start Timer1 void start_timer(void) { NRF_TIMER1->MODE = TIMER_MODE_MODE_Timer; NRF_TIMER1->TASKS_CLEAR = 1; // set prescalar n // f = 16 MHz / 2^(n) uint8_t prescaler = 0; NRF_TIMER1->PRESCALER = prescaler; NRF_TIMER1->BITMODE = TIMER_BITMODE_BITMODE_16Bit; // 16 MHz clock generates timer tick every 1/(16000000) s = 62.5 nano s // With compare enabled, the interrupt is fired every: 62.5 * comp1 nano s // = 0.0625*comp1 micro seconds // multiply this by 2^(prescalar) uint16_t comp1 = 500; // set compare NRF_TIMER1->CC[1] = comp1; // set conversion factor countToUs = 0.0625 * comp1 * (1 << prescaler); //printf("timer tick = %f us ", countToUs); // enable compare 1 NRF_TIMER1->INTENSET = (TIMER_INTENSET_COMPARE1_Enabled << TIMER_INTENSET_COMPARE1_Pos); // use the shorts register to clear compare 1 NRF_TIMER1->SHORTS = (TIMER_SHORTS_COMPARE1_CLEAR_Enabled << TIMER_SHORTS_COMPARE1_CLEAR_Pos); // enable IRQ NVIC_EnableIRQ(TIMER1_IRQn); Serial.println("Entered 2"); // start timer NRF_TIMER1->TASKS_START = 1; } void setup() { // put your setup code here, to run once: Serial.begin(9600); delay(2000); start_timer(); } void loop() { // put your main code here, to run repeatedly: Serial.println("Entered 1"); __WFE(); }

Not able to setup timer interrupt in nRF51822

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