CPU：STC89C54RD+
晶震：11.0592M
A0 A1 A2 均接地 地址設置為0 OS腳和INT0相連并通過10K上拉到VCC；當轉換溫度超過極限溫度，輸出中斷蜂鳴器報警；刷新數碼管顯示溫度 共5位前一位表示正負溫度后三位為溫度125 - -55 最后一位為0.1度 最高可精確到0.125 數碼管圖略定時器100MS采集溫度一次

#include
#include
#include

sbit xiaoshu=P2^0; //COM口
sbit ge=P2^1;
sbit shi=P2^3;
sbit bai=P2^4;
sbit fh=P2^5;
sbit SDA_LM75=P1^0; //數據
sbit SCL_LM75=P1^1;
sbit BP=P2^1;
bit dp=0;
unsigned char JS=0;

#define LED P0 //8位數碼管 動態(tài)時時刷新

#define CONF 0X01 //配置寄存器
#define TEMP 0X00 //溫度寄存器 只讀
#define ALARM 0X03 //超溫關閉極限寄存器默認5000H
#define DELAY 0X02 //滯后寄存器默認4B00H
#define WADDR 0X90 //寫地址
#define RADDR 0X91 //讀地址

unsigned int tempdata=0; //全局變量申明溫度

unsigned char code tab[]={ 0x3f,0x30,0x6d,0x79,0x72,0x5b,0x5f,0x31,0x7f,0x7b,0x40};//共陰
//0, 1, 2 3 4 5 6 7 8 9
//unsigned char tab[]={ 0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};//共陽
//0, 1, 2 3 4 5 6 7 8 9

unsigned char code tabdp[]={ 0xbf,0xb0,0xed,0xf9,0xf2,0xdb,0xdf,0xb1,0xff,0xfb,0xc0};//共陰帶小數點
//0, 1, 2 3 4 5 6 7 8 9
//unsigned char tabdp[]={ 0x40,0x79,0x24,0x30,0x19,0x12,0x02,0x78,0x00,0x10};//共陽

void delay_xms(unsigned int count) //延時函數
{
register unsigned char j;
while (count --)
{
for (j=0;j<125;j++) //約1MS
{
}
}
}

void Led_Display(unsigned int i,bit mode) //顯示函數
{
if(mode)
LED = 0x40; //共陰負
//LED=0xBF;
else
LED = 0x00;
//LED= 0XFF;
fh = 1;
bai = 0;
shi = 0;
ge = 0;
xiaoshu=0;
delay_xms(1);
LED = tab[i/1000];
i%=1000;
fh = 0;
bai = 1;
shi = 0;
ge = 0;
xiaoshu=0;
delay_xms(1);
LED = tab[i/100];
i%=100;
fh=0;
bai = 0;
shi = 1;
ge = 0;
xiaoshu=0;
delay_xms(1);
LED = tabdp[i/10]; //帶小數點
fh=0;
bai = 0;
shi = 0;
ge = 1;
xiaoshu=0;
delay_xms(1);
LED = tab[i%10];
fh=0;
bai = 0;
shi = 0;
ge = 0;
xiaoshu=1;
delay_xms(1);
}

void delay(void) //延時函數
{
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
}

void start_lm75(void)//起始
{
SDA_LM75=1;
SCL_LM75=1;
delay();
SDA_LM75=0;
delay();
SCL_LM75=0;
}

void stop_lm75(void)//停止
{
SDA_LM75=0;
SCL_LM75=1;
delay();
SDA_LM75=1;
delay();
SCL_LM75=0;
}

void Check_Ack(void) //檢查應答信號
{
SDA_LM75=1;
SCL_LM75=1;
F0=0;
delay();
if(SDA_LM75) //如果數據為高 置位非應答標志FO
F0=1; //通用標志位 PSW狀態(tài)寄存器
SCL_LM75=0; //準備下一變化數據
}

void Ack(void) //發(fā)響應信號
{
SDA_LM75=0;
delay();
SCL_LM75=1;
delay();
SCL_LM75=0;
}

void no_Ack(void) //發(fā)非響應信號
{
SDA_LM75=1;
SCL_LM75=0;
delay();
SCL_LM75=1; //迫使數據傳輸結束
delay();
}

void send_byte(unsigned char temp) //發(fā)送一字節(jié)數據
{
unsigned char i=8;
while(i--)
{
SDA_LM75=(bit)(temp&0x80);
SCL_LM75=1;
delay();
SCL_LM75=0;
temp<<=1;
}
SCL_LM75=0;
delay();
SDA_LM75=1; //釋放SDA數據線
}

unsigned char read_byte(void) //讀一字節(jié)數據
{
unsigned char i=8;
unsigned char temp;
while(i--)
{
temp<<=1;
if(SDA_LM75)
temp++;
SCL_LM75=1;
delay();
SCL_LM75=0;
}
SCL_LM75=0;
delay();
SDA_LM75=1; //釋放SDA數據線
return (temp);
}

void Write_chardata(unsigned char addr,unsigned char tempdata)//寫配置寄存器
{
start_lm75();
send_byte(WADDR);
Check_Ack();
if(F0)
{
no_Ack();
return;
}
Ack();
send_byte(addr);
Check_Ack();
if(F0)
{
no_Ack();
return;
}
Ack();
send_byte(tempdata);
Check_Ack();
if(F0)
{
no_Ack();
return;
}
Ack();
delay();
stop_lm75();
}

void Write_intdata(unsigned char addr,unsigned int tempdata)//寫16位寄存器
{
unsigned char datahigh;
unsigned char datalow;
datahigh=(unsigned char)(tempdata>>8);
datalow=(unsigned char)(tempdata&0x00FF);
start_lm75();
send_byte(WADDR);
Check_Ack();
if(F0)
{
no_Ack();
return;
}
Ack();
send_byte(addr);
Check_Ack();
if(F0)
{
no_Ack();
return;
}
Ack();
send_byte(datahigh);
send_byte(datalow);
Check_Ack();
if(F0)
{
no_Ack();
return;
}
Ack();
delay();
stop_lm75();
}

unsigned char read_chardata(unsigned char addr) //讀8位寄存器
{
unsigned char temp;
start_lm75();
send_byte(WADDR);
Check_Ack();
if(F0)
{
no_Ack();
return 0;
}
Ack();
send_byte(addr);
Check_Ack();
if(F0)
{
no_Ack();
return 0;
}
Ack();
send_byte(RADDR);
Check_Ack();
if(F0)
{
no_Ack();
return 0;
}
Ack();
temp=read_byte();
stop_lm75();
return (temp);
}

unsigned int read_intdata(unsigned char addr) //讀16位寄存器
{
unsigned char temphigh,templow;
start_lm75();
send_byte(WADDR);
Check_Ack();
if(F0)
{
no_Ack();
return 0;
}
Ack();
send_byte(addr);
Check_Ack();
if(F0)
{
no_Ack();
return 0;
}
Ack();
send_byte(RADDR);
Check_Ack();
if(F0)
{
no_Ack();
return 0;
}
Ack();
temphigh=read_byte();
templow=(read_byte())&0xe0;
stop_lm75();
if(!(temphigh&0x80))
{
dp=0;
return (((temphigh<<8)|templow)>>5);
}
else
{
dp=1;
return (0x800-((temphigh<<8)|templow)>>5);
}
}

void initial() // 初始化LM75A
{
Write_chardata(CONF,0X20); //0S中斷模式，溫度轉換正常模式
Write_intdata(ALARM,0x3300); //100度極限 由高9位有效位組成 BIT15為1表示為負為0表示為正超過100度 觸發(fā)外部中斷0
Write_intdata(DELAY,0X4A80); // 95度后不報警
}

void int0_int() interrupt 0 using 1 // 外部中斷0服務函數
{
BP=0;
delay_xms(1000);
BP=1;
delay_xms(1000);
}
void t0_int() interrupt 1 using 1 //定時器0中斷服務函數
{
TR0=0;
TH0=0xdc; // 10MS中斷初值
TL0=0xff;
TR0=1;
JS++;
if(JS>10) //加到10為100MS
{
JS=0;
tempdata=read_intdata(TEMP); //采集數據
tempdata=(tempdata/8)*10; //轉換為溫度
}
}

void main() // 入口函數
{
IP=0X01;
TMOD=0X01;
TH0=0xdc; // 10MS中斷初值
TL0=0xff;
IT0=0; //外部中斷0采用電平觸發(fā)

ET0=1;
TR0=1; //開放定時器0中斷
EX0=1;
EA=1;
initial();
while(1)
{
if(dp)
Led_Display(tempdata,1);
else
Led_Display(tempdata,0);
}
}