51單片機(jī)利用IIC總線對(duì)LM75A溫度進(jìn)行讀取

#include "..configc8051f350.h"#include "..configconst.h"#include "..driversystem.h"#include "..driverother.h"#define IIC_WRITE 0#define IIC_READ  1#define VREF 24380static unsigned long sysclk=24500000;sbit SDA=P0^0;sbit SCL=P0^1;sbit led=P1^2; void Delay_us(unsigned int times){unsigned int i;for(i=0;iiic_start(void){SDA = 1;Delay_us(2);SCL = 1;Delay_us(2);SDA = 0;Delay_us(2);  }					  //iic通信起始信號(hào)void iic_stop(void){SDA = 0;Delay_us(2);SCL = 1;Delay_us(2);SDA =1;}				      //iic通信終止信號(hào)void iic_ack(void)                      { SCL = 0;SDA = 0;Delay_us(2);SCL = 1;Delay_us(2);  SCL = 0;Delay_us(1); SDA = 1;}						//發(fā)送應(yīng)答信號(hào)函數(shù)bool read_ack(void)                      { bool flag;SCL = 0;Delay_us(2);    SDA = 1;SCL = 1;Delay_us(2);flag = SDA; SCL = 0;  return flag;}						//iic應(yīng)答函數(shù)void iic_nack()                     {   SDA = 1;Delay_us(2);      SCL = 1;Delay_us(2);      SCL = 0;}                        //iic非應(yīng)答函數(shù)unsigned char get_byte(void)                                 {unsigned char dd;int i;dd=0;SDA = 1;for (i=0;i<8;i++){Delay_us(1);SCL = 0;Delay_us(5);SCL = 1;Delay_us(2); dd<<=1;if (SDA)dd|=0x01;Delay_us(1);}         SCL = 0;Delay_us(1);return dd;}					     //輸入一個(gè)字節(jié)void out_byte(unsigned char dd)                      {unsigned char i;for(i=0;i<8;i++){  SCL = 0;Delay_us(0);			SDA = (dd & 0x80)>>7;Delay_us(2);         SCL = 1;Delay_us(3);dd <<= 1;} SCL = 0;    }					     //輸出一個(gè)字節(jié)bool iic_write_addr(unsigned char addr,unsigned char data_addr){iic_start();out_byte(addr); read_ack();   out_byte(data_addr);read_ack();     return TRUE;          }                        //寫入器件地址和所需讀取寄存器的地址void IICA_Read(unsigned char id, unsigned char addr, unsigned char *p, unsigned int len){                                                    int i;bit EA_SAVE = EA;EA = 0;iic_write_addr(id|IIC_WRITE,addr);  iic_start();out_byte(id|IIC_READ);read_ack();     for (i=0;i總線讀取多個(gè)數(shù)據(jù)float readTemperature(){unsigned char id=0x90;unsigned char addr=0x00;unsigned int len=2;unsigned char temp[2]={0};float temp_value=0.0;unsigned int temp_high=0;unsigned int temp_low=0;unsigned int low=0;unsigned int tempforh=0;unsigned int judge_posneg=0;IICA_Read(id,addr,temp,2);temp_high=temp[0];temp_low=temp[1];low=temp_low>>5;tempforh=temp_high*8+low;judge_posneg=(temp_high & 0x80)>>7;if(judge_posneg==0){temp_value=tempforh*0.125;return temp_value;}else {tempforh=(tempforh^0x7FF)+1;temp_value=tempforh*(-0.125);   return temp_value;}}					    //讀取并計(jì)算當(dāng)前溫度float main(){float tempvalue=0.0;PCA0MD&=~0x40;    // 禁止看門狗定時(shí)器Sysclk_Init();    // 配置系統(tǒng)時(shí)鐘SysPort_Init();   // 端口配置tempvalue=readTemperature();while(1){led=1;Delay_ms(1000);led=0;Delay_ms(1000);}SDA=1;return tempvalue;}