Hello all!
I was using a routine to read the ADC, it worked for several hours/days without any problem.
I decided to add a Watchdog vector interrupt to read the ADC with an interval of 250ms (the timers doesn't have so long delay interval). After installing the routine I start seeing it was running 2, 3 or five minutes and stops at the ADC reading routine.
The code I have is the following:
ADC setup:
// ADC Enable ADCSRA |=(1<<ADEN); ADCSRA |=(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0); ADMUX |=(1<<REFS0); DIDR0 =0b00011111;
The ADC reading routine I had is the following:
uint16_t Read_ADC(uint8_t adc_adr)
{
uint16_t adc_value =0;
ADMUX = (adc_adr);
ADCSRA |=(1<<ADSC);
while (!(ADCSRA & (1<<ADIF))) {}
adc_value=ADCL;
adc_value+=(ADCH<<8);
ADCSRA|=(1<<ADIF);
return adc_value;
}
The watchdog timer setup is the following:
void WDT_on(void)
{
//_watchdog_reset();
MCUSR &= ~(1<<WDRF);
WDTCSR |=(1<<WDCE) | (1<<WDE);
// set prescaller to 0.250ms
WDTCSR= (0<<WDE)|(1<<WDIE) | (1<<WDP2);
}
The watchdog ISR routine is the following:
/****************************************************************
* This is a timer Watchdog interrupt routine with 0.25 ms interrupt interval
* The ADC4 is readed to measure 4 times the currente and the total added.*/
ISR(WDT_vect)
{
sbi(PORTD, 6);// to test the time to measure the current
if (I_status<=3)
{
current_avg += Read_ADC(4+64); // +64 is the REFS= bit, AVCC with external capacitor at AREF pin
I_status++;
cbi(PORTD, 6);// to test the time to measure the current
}
else
{
GPS_data[43]=(uint8_t)(current_avg>>8);
GPS_data[44]=(uint8_t)(current_avg);
current_avg=0;
I_status=0;
}
}
The above was the first setup. After looking in the forum a tutorial I saw a different approach to read the ADC, that is the following:
/****************************************************************
* This routine is to read the ADC. The ADC is going to read the
* motor battery voltage, receiver battery voltage, temperature and
* air speed.
*/
uint16_t Read_ADC(uint8_t adc_adr)
{
uint16_t adc_value =0;
ADMUX = (adc_adr);
ADCSRA |=(1<<ADSC);
while(ADCSRA & (1<<ADSC)); {} // this was modified
adc_value=ADCL;
adc_value+=(ADCH<<8);
ADCSRA|=(1<<ADIF);
return adc_value;
}
Instead of looking for the "ADIF: ADC Interrupt Flag" was changed to "Bit 6 "“ ADSC: ADC Start Conversion".
This doesn't make sense to me according to the device manual Atmega644P.
The fact is: i changed it and it has been running without problems.
Can some one explain me what is wrong in the first version?
Thanks.
Manuel
