init.c

这是Mega8I2c通讯时的主机访问程序.

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/signal.h>
#include <compat/twi.h>

#include "main.h"
#include "init.h"
#include "inter.h"
volatile  uint16_t cnt_t0; //记录t0发生的次数

void port_init(void)
{
   PORTB = 0xFF; //输出为高 
   DDRB  = 0xfC; //输出  pb0.1为输入
   PORTC = 0xfF; //m103 output only
   DDRC  = 0x07;
   PORTD = 0xFF;
   DDRD  = 0x00;
 
}

/*TIMER0 initialisation - prescale:1
 WGM: Normal 
 desired value: 38KHz
 actual value: 38.095KHz (0.2%)*/
void timer0_init(void)  //0.1毫秒定时   
{
  // TCCR0 = 0x00; //stop
   
   TCCR0 = 0x02; //start timer 8分频
   TCNT0 = 0x9B; //set count
   cnt_t0 = 0;
}

/*TIMER1 initialisation - prescale:1024
 WGM: 0) Normal, TOP=0xFFFF
 desired value: 1Sec
 actual value:  1.000Sec (0.0%)*/
void timer1_init(void)
{
   TCCR1B = 0x00; //stop
   TCNT1 = 0x0008; //setup
  // OCR1A = 0x0F42;
  // OCR1B = 0x0F42;
  // ICR1  = 0x0F42;
   TCCR1A = 0x00;
   TCCR1B = 0x01; //start Timer  1分频,内部晶振为1M
}

/*TIMER2 initialisation - prescale:128
 WGM: Normal
 desired value: 2mSec
 actual value:  1.979mSec (1.0%)*/
void timer2_init(void)
{
   TCCR2 = 0x00; //stop
   ASSR  = 0x00; //set async mode
   TCNT2 = 0xC7; //setup
   OCR2  = 0x39;
   TCCR2 = 0x05; //start
}
/*TWI初始化*/
void twi_init(void)
{
   TWCR= 0X00; //disable twi
   TWBR= 0x32; //set bit rate
   TWSR= 0x00; //set prescale
   TWAR= 0x00; //set slave address
  // TWCR= 0x04; //enable twi
}


void uart0_init(void)
{
    UCSRA=0x00;
	  UCSRB = (1<<RXEN)|(1<<TXEN)|(1<<RXCIE);
    UBRRL=(FOSC/16/(BAUD+1))%256;
	  UBRRH=(FOSC/16/(BAUD+1))/256;
	  UCSRC=(1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);//8位数据+1位STOP位
}

void init_devices(void)
{
	 port_init();
	 timer0_init();
// timer1_init();
// timer2_init();
//	spi_init();
   twi_init();
	 uart0_init();
	 putchar('O');
	 putchar('K');
//	comparator_init();
//	adc_init();
//	 lcd_init();
	 MCUCR = 0x08;
	 OSCCAL = 0xAF;
	 GICR  = 0x80;
 	 TIMSK |= _BV(TOIE0);      // enable T0 interrupt
}