tmp_rec.c

vxworks网络通信实例

#pragma SMALL DB OE
#include <reg51.h>
#include "tmp_rec.h"

sbit SDA = P3^0;
sbit SCL = P3^1;

/*************************************************************************/

void pause_short (void) {
    int i;
    
    for ( i = 0; i  < 5; i++ );
}


/*************************************************************************/


void StartI2C (void) {
    SDA = 1;
    SCL = 1;
    SDA = 0;
    pause_short();
    SCL = 0;
}

/*************************************************************************/

void StopI2C (void) {
    SCL = 0;
    SDA = 0;
    SCL = 1;
    pause_short();
    SDA = 1;
}

/*************************************************************************/

char ReadI2C (void) {
    char r;
    
    SDA = 1;  /* This just sets it to high impedence, the LM75 can still pull it low */
    SCL = 1;
    pause_short();
    r = SDA;  /* Read in bit */
    SCL = 0;
    pause_short();
    return r;
}

/*************************************************************************/

void WriteI2C (char write_bit) {
    SDA = write_bit;
    SCL = 1;
    pause_short();
    SCL = 0;
    pause_short();
}
/*************************************************************************/

void Address_LM75_read (void) {
	
    WriteI2C(1);
    WriteI2C(0);
    WriteI2C(0);
    WriteI2C(1);
    WriteI2C(0);/* Note:  This function only works for I2C devices at address 000 */
    WriteI2C(0);/* A2 = 0 */
    WriteI2C(0);/* A1 = 0 */
    WriteI2C(1);/* A0 = 0 */
    
}

/*************************************************************************/

char temperature (void) {
    char in_bit;
    char check;
    char t_8;
    char i;
	
    StartI2C();
	
    Address_LM75_read();
    
	check = ReadI2C();  /*  Check for LM75 acknowledgement */
    
	if ( check == 0 ) {
        t_8 = 0;
        for ( i = 7; i >= 0; i-- ) {
            in_bit = ReadI2C();
            t_8 = t_8 | ( in_bit << i );
        }
        WriteI2C(0);
        for ( i = 7; i > 0; i-- ) {
            in_bit = ReadI2C();  /* Read in lower 8 bits */
        }
        WriteI2C(0);
    }
    else {
        t_8 = 127;
    }
    StopI2C();
    return t_8;
}

/*************************************************************************/

unsigned char PrintTemperature (void)
{
	unsigned char temp;
	float fahr;
	float remainder;
	unsigned char rem;	

	
	temp = temperature();

	// Convert the char to an int
	fahr = 1.8 * (int)temp + 32;
	remainder = fahr;
	remainder = fahr - (int)fahr;
	remainder = remainder * 10;	
	rem = ((int)remainder % 10) + 48;
	
	GotoXY(0,0);
	PrintString("Temperat");

	GotoXY(1,0);
	PrintString("ure:");
	PrintInt( (int)fahr );
	PutChar('.');
	PutChar( rem );

	return temp;
}

/*************************************************************************/