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Issues With ADC

Dragonleon United States

Hardware: ATmega328P At 16MHz Software: C Project Atmel Studio 7.0

The program requires to read different frequencies from 1 2 3 Hz, when I put voltage 1 2 3 4 5 V [volts] but it does not work. in the oscilloscope. I do not know if the issue is with my atmega328p board or I miss something in the code. Always appear the frequency at 1.87kHz at any voltage like if it is not working the channel analog or ADC channel ADC1. I will appreciate a lot if you figure out the solution.



#define F_CPU	16000000

void Initialize_ADC0(void);

int main(void)
	int i, voltage = 0;
	char toggle = 0;
	DDRB = 1 << 5;              	// Set PB5 output
	Initialize_ADC0();          	// Initialize ADC0 for manual trigger

		ADCSRA = 0xC7;        		// start conversion
		_delay_us(260);			    // ensure max sampling rate not exceeded
		voltage = ADC & 0x3FF;     		// read voltage
		//if(voltage<10||voltage >0){
			toggle = toggle ^ 1;
			PORTB = (toggle & 0x01) << 5;	// toggle LED

			if (voltage<20){
			else if (voltage <40){
			else if (voltage <60){
			else if(voltage < 80){
			else if(voltage < 100){

	return 0;
void Initialize_ADC0(void)
	ADCSRA = 0x87;	//Turn On ADC and set prescaler (CLK/128)
	ADCSRB = 0x00;	//turn off autotrigger
	ADMUX = 0x01;    	//Set ADC channel ADC1


R Avinash Gupta
2016-06-04 05:04:02
are you trying to generate different frequencies (1,2,3,4 & 5) Hz when you input voltages of (1,2,3,4 & 5)?

This is what I understood from the code.

But you have written that "The program requires to read different frequencies..." that is confusing.
R Dragonleon
2016-06-04 05:29:21
Yes, I need to get different frequencies when I input different voltages.
R Avinash
2016-06-08 13:42:23

The proper method to generate waveform is to use the Compare module of the MCU. I have developed a code that can generate 1 Hz square wave signal on OC1A pin (PB1)(PIN 15 on 28 PIN DIP IC). The hex code is attached. Check it with your hardware and inform if you can successully get 1 HZ out.

Once this is ok I will complete the code as per your need.
R Avinash
2016-06-09 14:10:02
Waiting for your reply ...

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