lm75.c

LM75A数字接口温度传感器

//ICC-AVR application builder : 2007-6-4 20:56:48
// Target : M16
// Crystal: 3.6864Mhz
//功能 数字温度测量
//包含文件   LM75.h，I2C.H，LM75.H
#include <iom16v.h>
#include <macros.h>
#include <LM75.h>
void send_a_byte(unsigned char i);

unsigned char get_temp;

void port_init(void)
{
 //PORTB = 0x00;
 //DDRB  = 0x00;
 PORTC = 0x03; //SCL SDA上拉
 DDRC  = 0x00;
 //PORTD = 0x00;
 //DDRD  = 0x00;
}

void c_tmp(unsigned int aa) //字符方式显示温度值
{//正温度显示
 unsigned char cc;
 if((aa&0x0400)==0)
 {
  send_a_byte('+');  
 }
 else  //负温度显示
 { 
  aa=(0x07ff-aa)+1;
  send_a_byte('-');  
 }
  cc=(char)(aa>>3);
  send_a_byte(cc/100+0x30);
  send_a_byte(cc%100/10+0x30);
  send_a_byte(cc%100%10+0x30);
  send_a_byte('.');
  send_a_byte('C'); 
  send_a_byte(0x0a);
  send_a_byte(0x0d);
}

void LM75_init(void)
{  
  LM75_Write(CONFIG,2,0,0); //POINT 
 // LM75_Write(TSET,0x7d,0,1);//125 c
 // LM75_Write(THYST,0x64,0,1);//100 c
}

void send_a_byte(unsigned char i)
{
 while ( !( UCSRA & (1<<UDRE)) );//发送数据
   UDR=i;
}
//UART0 initialize
// desired baud rate: 9600
// actual: baud rate:9600 (0.0%)
void uart0_init(void)
{
 UCSRB = 0x00; //disable while setting baud rate
 UCSRA = 0x00;
 UCSRC = BIT(URSEL) | 0x06;
 UBRRL = 0x17; //set baud rate lo
 UBRRH = 0x00; //set baud rate hi
 UCSRB = 0x98;
}

//
#pragma interrupt_handler uart0_rx_isr:iv_USART0_RXC
void uart0_rx_isr(void)
{
 unsigned char i;
 i=UDR;
 send_a_byte('T');
 send_a_byte(0x0a);
 send_a_byte(0x0d);
 get_temp=1;
}

//TWI initialize
// bit rate:8
void twi_init(void)
{
 TWCR= 0X00; //disable twi
 TWBR= 0x08; //set bit rate 100KHz
 TWSR= 0x00; //set prescale
 TWAR= 0x00; //set slave address
 TWCR= 0x04; //enable twi
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 twi_init();
 uart0_init();
 
 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x00; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

//
void main(void)
{
 //unsigned char i;
 unsigned char *resever,re;
 unsigned int temper;
 init_devices();
 //insert your functional code here...
 while(1)
 {
    if(get_temp)
	{	
	get_temp=0;	
	re=LM75_Read(TEMP,resever,2);//)==0);//返回0=错误
   	temper=*resever-1;
	temper=((((temper<<8)+*resever)>>5)&0x07ff); //存放温度值
	//re=(char)temper;//存放温度值
	//send_a_byte(re);
	c_tmp(temper);
	
  	}
 }
}