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Trail ES Solution

The document contains code for an AVR microcontroller that toggles two pins with a delay, along with an explanation of how a cadmium-sulfide sensor works in relation to light and resistance. It also discusses calculating Timer Frequency based on a student ID and configuring the ADC settings for input and conversion. Lastly, it mentions enabling ADC interrupts while keeping certain settings unchanged.

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vipra.19
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26 views2 pages

Trail ES Solution

The document contains code for an AVR microcontroller that toggles two pins with a delay, along with an explanation of how a cadmium-sulfide sensor works in relation to light and resistance. It also discusses calculating Timer Frequency based on a student ID and configuring the ADC settings for input and conversion. Lastly, it mentions enabling ADC interrupts while keeping certain settings unchanged.

Uploaded by

vipra.19
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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task 1:

a).

#include <avr/io.h>
#include <util/delay.h>
//From util/delay.h use void _delay_ms ( double __ms) ;
int main(int argc , char const * argv [ ] ) {
DDRD = 0b00000001; // Data Direction Register D:

while(1){
PD3 = 0b00000001;
PD7 = 0b00000000;
_delay_ms(500);
PD3 = 0b00000000;
PD7 = 0b00000001;
_delay_ms(500);
}
return 0;
}

b).

Cadmium-Sulfide: It's dependend on the volume of light, as more as

well have a light we get less resistance

we need output voltage to measure the difference between in/decresment light where

if no light than the resistance has full resistance => the output still the same

but if we turn on a light source , then the resistance decreases

the output voltage inverse proportion with the resistance

c).

// in this example we use the last three digits of our immatriculation number to find the TimerFreq

For example ur immatriculation number is: 3103400 -> TimerFreq = 1/400


timerFreq = 1/0.000238s = 4202 HZ

TimerFreq = 20 MHz / pre * top => 4202 Hz = 20MHz / pre * top

top = 20000000 Hz / 4202 Hz * pre

20000000 Hz / 4202 Hz * 1 = 4760 > 255

20000000 Hz / 4202 Hz * 8 = 595 > 255

20000000 Hz / 4202 Hz * 64 = 75 =< 255 no error,

-> pre = 64, top = 75

because with 8 bit we can cover until 11111111 (binary) = 255 (decimal)

d).

(i).

ADMUX =ADC7 // use pin ADC7 as input

ADMUX |= (1 << REFS0); // use AVcc as reference voltage

(ii).

ADCSRA |= (1 << ADEN); // Enable the ADC

ADCSRA |= (1 << ADSC); // Start the ADC conversion

// I don't know what he means with remaining hte ADC interrupt and ADC prescaler setting
unchanged !!

(iii).

while (ADSRA & (1<<ADSC)); //wait for end of conversion

ADCSRA |= (1 << ADIE); // Enable Interrupt

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