105 lines
3.1 KiB
Arduino
105 lines
3.1 KiB
Arduino
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/*
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This sketch illustrates how to set a timer on an SAMD21 based board in Arduino (Feather M0, Arduino Zero should work)
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*/
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uint32_t sampleRate = 1; //sample rate of the sine wave in Hertz, how many times per second the TC5_Handler() function gets called per second basically
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#define LED_PIN 13 //just for an example
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bool state = 0; //just for an example
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/*
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* TIMER SPECIFIC FUNCTIONS FOLLOW
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* you shouldn't change these unless you know what you're doing
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*/
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//Configures the TC to generate output events at the sample frequency.
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//Configures the TC in Frequency Generation mode, with an event output once
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//each time the audio sample frequency period expires.
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void tcConfigure(int sampleRate)
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{
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// Enable GCLK for TCC2 and TC5 (timer counter input clock)
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GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK0 | GCLK_CLKCTRL_ID(GCM_TC4_TC5)) ;
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while (GCLK->STATUS.bit.SYNCBUSY);
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tcReset(); //reset TC5
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// Set Timer counter Mode to 16 bits
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_MODE_COUNT16;
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// Set TC5 mode as match frequency
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_WAVEGEN_MFRQ;
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//set prescaler and enable TC5
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_PRESCALER_DIV1 | TC_CTRLA_ENABLE;
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//set TC5 timer counter based off of the system clock and the user defined sample rate or waveform
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TC5->COUNT16.CC[0].reg = (uint16_t) (SystemCoreClock / sampleRate - 1);
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while (tcIsSyncing());
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// Configure interrupt request
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NVIC_DisableIRQ(TC5_IRQn);
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NVIC_ClearPendingIRQ(TC5_IRQn);
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NVIC_SetPriority(TC5_IRQn, 0);
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NVIC_EnableIRQ(TC5_IRQn);
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// Enable the TC5 interrupt request
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TC5->COUNT16.INTENSET.bit.MC0 = 1;
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while (tcIsSyncing()); //wait until TC5 is done syncing
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}
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//Function that is used to check if TC5 is done syncing
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//returns true when it is done syncing
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bool tcIsSyncing()
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{
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return TC5->COUNT16.STATUS.reg & TC_STATUS_SYNCBUSY;
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}
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//This function enables TC5 and waits for it to be ready
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void tcStartCounter()
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{
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_ENABLE; //set the CTRLA register
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while (tcIsSyncing()); //wait until snyc'd
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}
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//Reset TC5
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void tcReset()
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{
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TC5->COUNT16.CTRLA.reg = TC_CTRLA_SWRST;
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while (tcIsSyncing());
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while (TC5->COUNT16.CTRLA.bit.SWRST);
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}
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//disable TC5
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void tcDisable()
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{
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TC5->COUNT16.CTRLA.reg &= ~TC_CTRLA_ENABLE;
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while (tcIsSyncing());
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}
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void TC5_Handler (void) {
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//YOUR CODE HERE
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if(state == true) {
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Serial.println("ON");
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digitalWrite(LED_PIN,HIGH);
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} else {
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digitalWrite(LED_PIN,LOW);
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Serial.println("OFF");
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}
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state = !state;
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// END OF YOUR CODE
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TC5->COUNT16.INTFLAG.bit.MC0 = 1; //don't change this, it's part of the timer code
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}
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void setup() {
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pinMode(LED_PIN,OUTPUT); //this configures the LED pin, you can remove this it's just example code
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Serial.begin(512000);
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tcConfigure(25); //configure the timer to run at <sampleRate>Hertz
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tcStartCounter(); //starts the timer
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}
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void loop() {
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//tcDisable(); //This function can be used anywhere if you need to stop/pause the timer
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//tcReset(); //This function should be called everytime you stop the timer
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}
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//this function gets called by the interrupt at <sampleRate>Hertz
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