Stopping ADC (Timer triggered) conversions after N readings.

Official Hardware Mega Due
1

Hi,

I have very weird issue, when reading specific number of ADC readings and I have no clue, why is that. I used to use this approach with UNO and it was OK, but here...I don't now what is wrong. Basically, I setup timers and ADC, but Timer is not started after configuration. It is started in main loop() event and when I start it, I run "while" loop to wait for conversions to be finished. ADC handler stops the timer. However, everytime I try to wait for completion with "while" controller stucks... but when I do the same with serial.read() (when I enter commands), code works. What do I miss here?

#define   SMP_RATE         200000UL 
#define   CLK_MAIN       84000000UL
#define   TMR_CNTR       CLK_MAIN / (2 * SMP_RATE)

const int sampleQty = 1024;
double samples[sampleQty];
double samples2[sampleQty];
int currSample;
volatile int isr_counter = 0;
volatile int dur, nowT;
volatile int stopper;
int dum1, dum2;

void setup_pio_TIOA0 () { // Configure Ard pin 2 as output from TC0 channel A (copy of trigger event)
	PIOB->PIO_PDR = PIO_PB25B_TIOA0 ;  // disable PIO control
	PIOB->PIO_IDR = PIO_PB25B_TIOA0 ;   // disable PIO interrupts
	PIOB->PIO_ABSR |= PIO_PB25B_TIOA0 ;  // switch to B peripheral
}

void timerConfig() {
	pmc_enable_periph_clk(ID_TC0); // enable timer 0, chan 0.

	TcChannel *pTcChan = &(TC0->TC_CHANNEL)[0];  // get TC0, chan 0 pointer.
	pTcChan->TC_CCR = TC_CCR_CLKDIS; // disable TC clock.
	pTcChan->TC_IDR = 0xFFFFFFFF; // disable interrupts.
	pTcChan->TC_SR; // clear status register.
 
	pTcChan->TC_CMR =	TC_CMR_TCCLKS_TIMER_CLOCK1 |  // use TCLK1 (prescale by 2, so 42MHz).
						TC_CMR_WAVE | // // waveform mode.
						TC_CMR_WAVSEL_UP_RC | // RC as threshold for PWM. 
						TC_CMR_EEVT_XC0 | // external events from XC0.
						TC_CMR_ACPA_CLEAR | 
						TC_CMR_ACPC_CLEAR |
						TC_CMR_BCPB_CLEAR |
						TC_CMR_BCPC_CLEAR;
	pTcChan->TC_RA = TMR_CNTR / 2;  // counter resets on RC.
	pTcChan->TC_RC = TMR_CNTR; // square wave.
	pTcChan->TC_CMR = (pTcChan->TC_CMR & 0xFFF0FFFF) | TC_CMR_ACPA_CLEAR | TC_CMR_ACPC_SET ;  // set clear and set from RA and RC compares
	
	setup_pio_TIOA0();
	//TC_Start(TC0, 0); ///
}

void adcConfig() {
	pmc_enable_periph_clk(ID_ADC); // enable ADC.
	adc_init(ADC, SystemCoreClock, ADC_FREQ_MAX, ADC_STARTUP_FAST); // dar paž?t d?l šito parametr?.
	NVIC_EnableIRQ (ADC_IRQn);   // enable ADC interrupt vector.
	
	ADC->ADC_IDR = 0xFFFFFFFF; // disable all interrupts.
	ADC->ADC_CGR = 0x15555555; // All gains set to x1.
	ADC->ADC_COR = 0x00000000; // All offsets off, but might be used in the future TODO.
	adc_disable_all_channel(ADC);

	adc_enable_interrupt(ADC, ADC_IER_EOC7); // enable EOC7 interrupt.
	adc_enable_channel(ADC, ADC_CHANNEL_7);
	adc_enable_channel(ADC, ADC_CHANNEL_6);
	adc_configure_trigger(ADC, ADC_TRIG_TIO_CH_0, 0);
}

void ADC_Handler(void) {
	if ((ADC->ADC_ISR & ADC_ISR_EOC7) && (ADC->ADC_ISR & ADC_ISR_EOC6)) {
		int val = *(ADC->ADC_CDR + 7);
		samples[currSample] = val - 2048;
		val = *(ADC->ADC_CDR + 6);
		samples2[currSample] = val - 2048;
		currSample += 1;
		if (currSample == sampleQty) {stopper = 1; TC_Stop(TC0, 0);} 
	}
	isr_counter += 1;
}

void setup() {
    Serial.begin(115200);
	adcConfig();	
	timerConfig();

	isr_counter = 0;
	dum1 = dum2 = 0;
	stopper = 0;
} 

void loop() {
	delay(100);
	stopper = 0;
	Serial.println("Before");
	TC_Start(TC0, 0);
	while (stopper == 0);
	Serial.println("Done");
		
	/* THIS APPROACH WORKS
	while (Serial.available()) {
		uint8_t a = Serial.read();
		if (a == 'x') {
			//isr_counter = 0;
			dum2 += 1;
			Serial.println(dum2);
			nowT = micros();
			TC_Start(TC0, 0);
			//adc_start(ADC);
			//while ((ADC->ADC_CR & ADC_CR_SWRST) != ADC_CR_SWRST) {};
			//for (int i = 0; i < sampleQty; i++) {
			//	Serial.println(samples[i], 2);
			//}
		} else {
			dum1 += 1;
			Serial.println(dum1);
			Serial.print(isr_counter); Serial.print(" ");
			Serial.print("avg. us: "); Serial.print(nowT); Serial.print(" "); Serial.print(dur); Serial.print(" ");
			if (sampleQty != 0) {Serial.println((float)dur/sampleQty, 4);} else {Serial.println(0, 4);}
			for (int i = 0; i < sampleQty; i++) {Serial.print(samples[i]); Serial.print("  "); Serial.println(samples2[i]);}
		}
	}*/
}

Is there a better way to read chunks of ADC values with DUE? Any recommendations or suggestions are welcome.

Thanks alot for your help.

2

Anyone? Probably I should have posted this into programming forum, but... I do not know, how to move it there.

I really need to finish this until tomorrow.

Thanks.