Question

ANSWER THE QUESTION IN THE END

READING THE DIAL WITH THE AVR ATMEGA16 MICROCONTROLLER #include <axc/ie.h> int main(void) int ads.valusimm 1/Variable used to store the value read from ADC DDRB = (1<<PBC); //PB® is an output ADMUX = (1<<REFSO); ADMUX &= -(1<<REFS1mm //Axcs(+5v) as voltage reference ADCSRA != ((1<<ADPS2) (1<<ADP51)|(1<<ADPS0)); //ecessalec at 128 ADCSRA |= (1<<ADEN); 1/Power up the ADC ADCSRA - (1<<ADSC); 1/Start converting ADCSRA |= (1<<ADATE); // finish the conversion automatically while(1) { //The infinite loop adc value = ADCW; //Read the ADC value iflads.value, > 512){ PORTB = (1<<PBP); //turn LED on } else { PORTB &= -(1<<PBD)mm //Else turn LED off } return; Question 2: Asnwer in one word sentence a. Why we compare the voltage measurements of the potentiometer with 512? b. If the CPU frequency is 4 MHz, what is the frequency of ADC using prescaler, at 128? c. What will happen if ADEN bit of ADCSRA register not set 1 in the previous code? Answer:

Answer 1

(a).

The condetion of turning the LED on is when the ADC output is more than "11111111". When the Decimal equivalent of the Digital Output from the ADC is more than decimal equivalent of "11111111" (512-dec), the ATMEGA16 Microcontroller turns on the LED. So, 512 is taken as the threshold value which is compared with the real time output of the ADC.

(b).

CPU frequency = 4 MHz.

Prescaler Value = 128.

ADC Frequency:

$f=\frac{4\times10^6}{128}=31.25\ kHz$

(c).

If the ADEN and ADCSRA registers are not turned to Logic "1", the ADC will not be powered on and the Prescaler conversion will not be done.