3.2 ADC Series Mode With Event Trigger

1. Change the Conversion mode by changing the Command register:

   ADC0.COMMAND = ADC_MODE_SERIES_gc | ADC_START_EVENT_TRIGGER_gc;

2. Make the ADC trigger an ADC result ready interrupt to wake up the CPU from sleep every time an ADC result is ready by adding the following line to the adc_init():

   /*Activate interrupt on Result ready to wake up from sleep*/
   ADC0.INTCTRL = ADC_RESRDY_bm;

3. Change the following code to adc_init() to enable the ADC to run in Standby sleep mode:

   ADC0.CTRLA = ADC_ENABLE_bm | ADC_RUNSTDBY_bm; /*Enable the ADC and run in standby sleep mode*/

4. Change the adc_result_is_ready() to the following, so it works with an interrupt based ADC:

   bool adc_result_is_ready()
   {
   	if(adc_result_is_ready_flag){
   		adc_result_is_ready_flag = 0;
   		return true;
   	}
   	return false;
   }

RTC.PER = (RTC_CLOCK/(float)(ADC_SAMPLING_FREQ))+0.5;

#define ADC_SAMPL_FREQ (uint16_t)(ADC_RESULT_FREQ << ADC_SAMPLES)

1. Study the slpctrl_init() in sleep_control.c to understand how the sleep controller is configured.
2. Add slpctrl_init() to the initialization sequence in the main function.
3. Add sei() to the end of the initialization sequence in the main function to enable interrupts so the device can wake up from Standby sleep mode.
4. Add sleep_cpu() to the while function so the device will go to sleep between each result:

   while (1) 
   {
   	sleep_cpu(); 
   	if(adc_result_is_ready())
   	{
   		adc_t.adc_sample = adc_get_sample();
   		adc_t.adc_result = adc_get_result();
   		adc_t.adc_average_result = adc_t.adc_result>>ADC_SAMPLES;
   		trasmit_to_DV();
   		PORTB.OUTTGL = LED0_bm;	
   	}
   }
   

5. Add the following code to the end of the transmit_to_DV() in data_streamer.c to make sure the device does not go to sleep before the transmission is complete:

   while (!(USART0.STATUS & USART_TXCIF_bm)); /* Wait for all USART transmission to be finished */
   USART0.STATUS |= USART_TXCIF_bm; /* Clear Tx complete flag */