adc._c

atmega8的片内A/D转换操作

//ICC-AVR application builder : 2005-3-1 22:02:29
// Target : M8
// Crystal: 8.0000Mhz

#include <iom8v.h>
#include <macros.h>

void port_init(void)
{
 PORTB = 0xFF;
 DDRB  = 0x00;
 PORTC = 0x7F; //m103 output only
 DDRC  = 0x00;
 PORTD = 0xFF;
 DDRD  = 0x00;
}

//TIMER0 initialisation - prescale:256
// WGM: Normal
// desired value: 5mSec
// actual value:  4.992mSec (0.2%)
void timer0_init(void)
{
 TCCR0 = 0x00; //stop
 TCNT0 = 0x64; //set count
 TCCR0 = 0x04; //start timer
}

#pragma interrupt_handler timer0_ovf_isr:10
void timer0_ovf_isr(void)
{
 TCNT0 = 0x64; //reload counter value
}

//ADC initialisation
// Conversion time: 13uS
void adc_init(void)
{
 ADCSR = 0x00; //disable adc
 ADMUX = 0x00; //select adc input 0
 ACSR  = 0x80;
 ADCSR = 0x83;
}

//call this routine to initialise all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 timer0_init();
 adc_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x01; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialised
}

//
void main(void)
{
 init_devices();
 //insert your functional code here...
}