Pulse generator with different duty cycle using microcontroller with c code

[ruhulamineee]

Hello Every One,

can i use atmega8 for pulse generator in c programing with different duty cycle like 10%, 30%, 50%.

my code was:

if(adc(0)==1){PROTB.0=1; delay_ms(15); PORTB.0=0;delay_ms(5)};
if(adc(1)==1){PROTB.1=1; delay_ms(14); PORTB.1=0;delay_ms(6)};

but its not working according to my duty cycle. how can i crate proper duty cycle.

Thank u

 

[kvtal]

In a periodic event, duty cycle is the ratio of the duration of the event to the total period of a signal.
duty cycle D=a/b
where
a is the duration that the function is active.
b is the period of the function.

if the delays are according to the formula u can get the exact duty cycle

 

[ruhulamineee]

Thanks for the information kvtal,

for the 50 Hz signal, Time Period is 20ms. According to desired system. for 75% duty cycle it is needed high for 15ms and low for 5ms. again for 70% duty cycle it is needed high for 14ms and low for 5ms.

the code was:
#include <mega8.h>

#include <delay.h>

#define ADC_VREF_TYPE 0x00

// Read the AD conversion result
unsigned int read_adc(unsigned char adc_input)
{
ADMUX=adc_input | (ADC_VREF_TYPE & 0xff);
// Delay needed for the stabilization of the ADC input voltage
delay_us(1);
// Start the AD conversion
ADCSRA|=0x40;
// Wait for the AD conversion to complete
while ((ADCSRA & 0x10)==0);
ADCSRA|=0x10;
return ADCW;
}

// Declare your global variables here

void main(void)
{

// Declare your local variables here

// Input/Output Ports initialization
// Port B initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=Out Func0=Out
// State7=T State6=T State5=T State4=T State3=T State2=T State1=0 State0=0
PORTB=0x00;
DDRB=0x03;


while (1){
if(read_adc(0)>0){PORTB.0=1; delay_ms(15); PORTB.0=0;delay_ms(5);};
if(read_adc(1)>0){PORTB.1=1; delay_ms(14); PORTB.1=0;delay_ms(6);};
};
}

Ans: for 75% duty cycle and 70% duty cycle receptively


why this is happing and how do i get exact duty cycle where frequency is constant 50H

 

[kvtal]

what is happening i can not see the images

 

[ruhulamineee]

it could be
while (1){
if(read_adc(0)>0){PORTB.0=1; delay_ms(15); PORTB.0=0;delay_ms(5);}; // for 75% duty cycle
if(read_adc(1)>0){PORTB.1=1; delay_ms(14); PORTB.1=0;delay_ms(6);}; // for 70% duty cycle
};


but its not working. is there any way to get perfect duty cycle as i wish.