How can you measure values from several ADC channels on a DE1 SoC?

TAhme12 · ‎05-04-2019

Hi,

By following the DE1_SoC_ADC example of the DE1 revF CD, I can collect measurements from a single ADC channel. I have connected a pulse rate sensor to the ADC and am using a timer interrupt on the NIOS II processor to take measurements from the ADC as 2ms interval. However, when I want to measure a different channel, I am unable to receive and data from it?

Any help would be appreciated.

int ch[2];
int main(){
 
	printf("Pulse Rate Demo\r\n");
 
	// register the timer irq to be serviced by handle_timer_interrupt() function
	 alt_irq_register(TIMER_IRQ, 0, handle_timer_interrupt);
	 // activate the time
	 IOWR_ALTERA_AVALON_TIMER_CONTROL(TIMER_BASE,
	                 ALTERA_AVALON_TIMER_CONTROL_CONT_MSK
	               | ALTERA_AVALON_TIMER_CONTROL_START_MSK
	               | ALTERA_AVALON_TIMER_CONTROL_ITO_MSK);
 
	while(1){
		ch[0] = IORD(SW_BASE, 0x00) & 0x07; 
 
		ch[1] = IORD(SW_BASE, 0x4) & 0x07; 
 
		// set measure number for ADC convert
		IOWR(ADC_LTC2308_BASE, 0x01, nReadNum);
 
		//printf("%d,%d,%d,%d, %d,%d\n",thresh,T,P,N,adcVal,BPM-1);
		printf("ch:%d, i:%d, BPM:%d\n",ch[i],i,BPM);
		usleep(200*1000);
	}
}
 
 
void handle_timer_interrupt(void*p, alt_u32 param)
{
   // clear irq status in order to prevent retriggering
   IOWR_ALTERA_AVALON_TIMER_STATUS(TIMER_BASE, 0);
   // your isr code here
 
   i=!i;
 
 
  if(i==1){
   // start measure
   		IOWR(ADC_LTC2308_BASE, 0x00, (ch[0] << 1) | 0x00);
   		IOWR(ADC_LTC2308_BASE, 0x00, (ch[0] << 1) | 0x01);
   		IOWR(ADC_LTC2308_BASE, 0x00, (ch[0] << 1) | 0x00);
   		i=0;
   }
   else {
		IOWR(ADC_LTC2308_BASE, 0x00, (ch[1] << 1) | 0x00);
		IOWR(ADC_LTC2308_BASE, 0x00, (ch[1] << 1) | 0x01);
		IOWR(ADC_LTC2308_BASE, 0x00, (ch[1] << 1) | 0x00);
   }
 
   		// wait measure done
   		while ((IORD(ADC_LTC2308_BASE,0x00) & 0x01) == 0x00);
 
   		Value = IORD(ADC_LTC2308_BASE, 0x01);
 
   		adcVal = ((float)(Value/1000.0)/5)*1024;
                .............................................

Rahul_S_Intel1 · ‎05-08-2019

May I have the project file for reference