DS18b20在Atmega8下的编程，串口通讯电脑显现

=******************************************************

MCU:Atmega8

内部振荡器：8M

环境：ICCAVR 7.0

程序：sdyzxue 薛海涛

2010/06/16

=*******************************************************
#include
#include
#define fosc 8000000
#define baud 9600
#define SEI() asm(“sei”)
#define CLR_DIR_1WIRE DDRC&=~BIT(1) //只需修正这儿的参数就可以了！呵呵！
#define SET_DIR_1WIRE DDRC|=BIT(1) //里边什么都不必该！
#define CLR_OP_1WIRE PORTC&=~BIT(1)
#define SET_OP_1WIRE PORTC|=BIT(1)
#define CHECK_IP_1WIRE (PINC & 0x02) //检测
unsigned char wmh,wmm,wml;
unsigned int temp,temp0,temp1,temp2;

unsigned char RX_data[10]={0} ; //串口接纳的数据
unsigned char RX_counter=0 ; //串口接纳到的字节数计数器

void delay_1us(void) //1us延时函数
{
asm(“nop”);
}

void delay_nus(unsigned int n) //N us延时函数
{
unsigned int i=0;
for (i=0;i delay_1us();
}

void delay_1ms(void) //1ms延时函数
{
unsigned int i;
for (i=0;i<1140;i++);
}

void delay_nms(unsigned int n) //N ms延时函数
{
unsigned int i=0;
for (i=0;i delay_1ms();
}

void putchar(unsigned char c)
{
while (!(UCSRA&(1< UDR=c;
}

//字符输入函数
unsigned char getchar(void)
{
//等候承受字符
while(!(UCSRA&(1< return UDR;
}

//字符串输出函数
int puts(char *s)
{
while (*s)
{
putchar(*s);
s++;
}
return 1;
}

//含回车换行的字符串输出函数
void puts_hh(char *s)
{
while (*s)
{
putchar(*s);
s++;
}
// putchar(0x0a); //换行
putchar(0x0d); //回车

}

//UART初始化
void uart_init(void)
{

UCSRB=(1< //答应发送和接纳 (RXCIE) 并呼应接纳完结中止
UBRRL=(fosc/16/baud+1)%256;
UBRRH=(fosc/16/baud+1)/256;
UCSRC=(1< //8位数据+1位中止位
}

#pragma interrupt_handler UART_rx: iv_USART_RX
void UART_rx(void) //串口接纳中止函数
{ RX_data[RX_counter] = UDR;

if (RX_data[RX_counter]==t)
{
RX_data[0]=RX_data[RX_counter];
RX_counter=0;
}

RX_counter++; //接纳的字节数计数

}
void init_1820()
{
SET_DIR_1WIRE; //设置PC2 为输出
SET_OP_1WIRE;
CLR_OP_1WIRE;
delay_nus(480); //480us以上
SET_OP_1WIRE;
CLR_DIR_1WIRE;
delay_nus(20); //15~60us
while(CHECK_IP_1WIRE);
SET_DIR_1WIRE;
SET_OP_1WIRE;
delay_nus(140); //60~240us
}
void write_1820(unsigned char x)
{
unsigned char m;
for(m=0;m<8;m++)
{
CLR_OP_1WIRE;
if(x&(1< //写数据了，先写低位的！
SET_OP_1WIRE;
else
{CLR_OP_1WIRE;}
delay_nus(40); //15~60us
SET_OP_1WIRE;
}
SET_OP_1WIRE;
}
unsigned char read_1820()
{
unsigned char temp,k,n;
temp=0;
for(n=0;n<8;n++)
{
CLR_OP_1WIRE;
SET_OP_1WIRE;
CLR_DIR_1WIRE;
k=(CHECK_IP_1WIRE); //读数据,从低位开端
if(k)
temp|=(1<
else
temp&=~(1<
delay_nus(50); //60~120us
SET_DIR_1WIRE;
}
return (temp);
}

void gettemp() //读取温度值
{
unsigned char temh,teml;
init_1820(); //复位18b20
write_1820(0xcc); // 宣布转化指令
write_1820(0x44);
init_1820();
write_1820(0xcc); //宣布读指令
write_1820(0xbe);
teml=read_1820(); //读数据
temh=read_1820();
temp0=teml&0x0F; //小数位
temp1=(temh<<4)|(teml>>4); //整数位
temp2=(temh>>3)&0x1F; //正负温度
wmh=temp1/100; //一百以上输出百位字
wmm=(temp1%100)/10; //出口参数！wmh是显现的高位十位，wml使显现的低位 个位
wml=(temp1%100)%10;
temp=temp0*625; //小数值
}

void main(void) //主函数
{
OSCCAL=0xb7;//体系时钟校准，不同的芯片和不同的频率，
DDRC=0XFF;
PORTC=0X00;
uart_init();
while(1)
{ gettemp();

puts_hh(“=====Temp Test=====”);
if(temp2)//负温度
{

putchar(-);

}
if(!temp2)//正温度
{

putchar(+);

}

putchar(wmh+0x30);//百
putchar(wmm+0x30);//十
putchar(wml+0x30);//个
putchar(.);
putchar(temp/1000+0x30);
putchar((temp%1000)/100+0x30);
putchar((temp%100)/10+0x30);
putchar(temp%10+0x30);

putchar(0x0d); //回车

delay_nms(10000);
}
}