111._c

来自「温度测量ds18b20.rar」· _C 代码 · 共 56 行

//ICC-AVR application builder : 2008/11/17 22:33:32
// Target : M8
// Crystal: 8.0000Mhz

#include <iom8v.h>
#include <macros.h>
#include "mydelay.h"
#define uchar unsigned char
void delay0ms5us(void)
{
/*精确延时0ms 5us ,晶振8MHz*/
/*us级精确延时 766us/晶振以内 延时=1+n*3 */
// CLI;//屏蔽中断
asm("LDI R18,10");//1t ，寄存器R15~R30
asm("CLZ");//1t
asm("LOOP1:DEC R18");//1t
asm("BRNE LOOP1");//1t或2t//标志位Z是0就转移
asm("NOP");//1t
asm("NOP");//1t
// SEI;
/*us级精确延时 24543us以内,可用nop补足余数*/
//===精确延时 4.125us,晶振8MHz ===//
//===调用函数及返回花费0.875us==//
}

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

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

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

void main(void)
{
  init_devices();
  PORTC=0x00;
  delay0ms5us();
  PORTC=0xff;
}