ZERO using timer and DMA to drive DAC

mantoui · November 29, 2015, 6:09pm

Here is a simple proof of concept of using TCC0 timer to drive DAC from circular DMA buffer.

manitou48/ZERO/blob/master/dacdma.ino

//  dacdma
//  TCC timer   OVF triggers DMA to write to DAC (A0)


// use pin 12 for PWM TCC0 ch3 
#define PWMPIN 12
#define TCCx TCC0
#define TCCchannel 3

#define syncTCC while (TCCx->SYNCBUSY.reg & TCC_SYNCBUSY_MASK)

// TCC freq = 48mhz/period
#define PERIOD 0x1000
#define DUTY (PERIOD/2)

void timer_init() {
	uint32_t cc;

	analogWrite(PWMPIN,0);  // init clock,timer,pin, and zero TODO just timer
	TCCx->CTRLA.reg &= ~TCC_CTRLA_ENABLE;   // disable

This file has been truncated. show original

The sketch uses the PWM timer TCC0 on pin 12 (not used), and then overrides the frequency and duty cycle. A circular buffer of 128 half-words is used by the DMA to fill the DAC on each timer tick. Example can use sawtooth or sine wave in buffer.
Verified with scope.

AloyseTech · November 29, 2015, 6:54pm

Great, as always ! Thanks

electro_95 · August 15, 2017, 8:23am

Thanks as always for these useful examples. I'm trying to adapt this to use the DMA to copy cc0 each time that the TCC0 MC1 interrupt occurs.

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ZERO using timer and DMA to drive DAC

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