Temperature controller using PIC16F877A microcontroller Software is

Temperature controller using PIC16F877A microcontroller
Software is written in C language and compiled using HI-TECH ANSI C Compiler
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//program for temperature monitoring system written for PIC16F877A //
//below 36.5ºC LED switches OFF //above 37.5ºC LED switches ON //
//between 36.5C and 37.5 C LED Toggles ON/OFF//
//timer delay~0.5sec //
//10/30/09//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#define LED PORTB.F1 //LED port pin
#define max_count 15
#define low_temp 30 //define lower temperature range
#define high_temp 40 //define higher temperature range
//Function declarations
void send_data(unsigned char *p,unsigned char no_of_bytes);
unsigned char hex_to_ascii(unsigned char number);
//global variable declarations
unsigned short int timer_counter=0;
unsigned char mes_temp[]={"temp:"},mes_sensor[]={"sdata: "};
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//timer 0 ISR; increments timer_counter ; reinitializes TMR0 //
//input: none output: none affected: timer_counter, TMR0,INTCON //
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void interrupt() //timer0 interrupt
{
timer_counter++; //increment counter
TMR0 = 96; //reinitialize TMR0 register

INTCON.TMR0IF=0; //clear timer0 overflow interrupt flag bit
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
////main program starts here; reads ADC channel 0; calibrates the sensor data; //
////sends to serial port //
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void main(void)
{
unsigned char sensor_data,sensor_data1,sensor_data2,high_temp_flag,low_temp_flag,med_temp_flag,i;
TRISA=0xFF; //configure PORTA as input
TRISB=0; //configure PORTB as output
PORTA=0; //clear PORTA
PORTB=0; //clear PORTB
Usart_Init(9600); //initialize serial port using built in function
//if built in function is not used then use bellow commented //codes to initialize serial port
//SPBRG=103; //for 9600 baud rate (with 4MHz)
//TXSTA=0x22; //8 bit transmission, asynchronous, low baud rate, no parity
//RCSTA=0x90; //8 bit receive, enable serial port, no parity
//PIE1.RCIE=1; //enable receive interrupt
//PIE1.TXIE=1; //enable transmission interrupt
//Configure A/D
ADCON0=0x80; //Fosc/32, AN0, A/D disabled
ADCON1=0x80; //right justified, Fosc/32, analog inputs
ADCON0.ADON=1; //enable ADC module
OPTION_REG=0b00000111; //disable portb pullup, -ve edge, internal clock, increment
INTCON.TMR0IE=1; //enable timer0 interrupt
INTCON.PEIE=1; //enable peripheral interrupts
//on +ve edge, prescalar-0:256

INTCON.GIE=1; //enable global interrupt
for(;;)
{
INTCON.TMR0IE=1; //enable timer 0 interrupt
while(timer_counter!=max_count) //timer0 delay; wait till delay elapsed
{asm nop;}
timer_counter=0; //delay over; reinitialize counter
//Delay_ms(450); //without timer delay we can use built in delay function
sensor_data=Adc_Read(0); // read A/D using built in function
//ADCON0.GO=1; //start A/D conversion
//while(ADCON0.GO){} //wait till A/D conversion is over (1.6µS )
//sensor_data=ADRESL; //get ADC data; lower byte is sufficient
for(i=0;i

if(sensor_data2>high_temp) //check for temperature range
{high_temp_flag=0xFF; //if temperature > 37.5ºC set high_temp_flag
low_temp_flag=0;} //clear low_temp_flag
else if(sensor_data2
{low_temp_flag=0xFF; //if temperature
high_temp_flag=0;} //clear high_temp_flag
else
{low_temp_flag=0;
high_temp_flag=0;} //to avoid false triggering of LED clear both temp flags
if(high_temp_flag==0xFF) //check flag conditions;
LED=1; //if high_temp_flag is set switch ON LED
//PORTB.F1=1;
else if(low_temp_flag==0xFF) //if low_temp_flag is set switch OFF LED
LED=0;
//PORTB.F1=0;
else //if temperature is in between 36.5ºC and 37.5ºC blink LED
LED=~LED; //toggle LED
//PORTB.F1= ~PORTB.F1;
for(i=0;i

TXREG=sensor_data1; //send to serial port
}
}
/////////////////////////////////////////////////////////////
//function to convert hex number to ASCII format //
unsigned char hex_to_ascii(unsigned char number)
{ //if hex number is 0 to 9 add 0x30
if(number