uint16_t rd_temp()
{
/*
TWCR = TWCR_START; //send start condition
TWDR = LM73_READ; //send device addr, read bit set
TWCR = TWCR_RACK; //receive data byte, return ACK
while(!(TWCR & (1<<TWINT))){} //wait for data byte to come in
if(TW_STATUS != TW_MR_DATA_ACK){return(1);} //byte 1 read failure
int lm73_temp_high = TWDR; //store temp high byte
TWCR = TWCR_RNACK; //recv temp low byte, return NACK
while(!(TWCR & (1<<TWINT))){} //wait for data byte to come in
if(TW_STATUS != TW_MR_DATA_NACK){return(2);} //byte 2 read failure
int lm73_temp_low = TWDR; //store temp low byte
TWCR = TWCR_STOP; //conclude transaction
return(lm73_temp_low + (lm73_temp_high<<8)); //return success value
*/
TWCR = TWCR_START; //send start condition
while (!(TWCR & (1<<TWINT))); //wait for start condition to transmit
if((TWSR & 0xF8) != TW_START){
string2lcd("ERROR1"); //check start status
}
TWDR = LM73_READ; //send device addr, read bit set
TWCR = (1<<TWINT)|(1<<TWEN);
while (!(TWCR & (1<<TWINT)));
if((TWSR & 0xf8) != TW_MR_SLA_ACK){
string2lcd("ERROR2");
}
TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWEA);//enable TWI and ACK
while(!(TWCR & (1<<TWINT)));
uint8_t indoor1= TWDR;//assign byte read to variable
if((TWSR & 0xF8) != TW_MR_DATA_ACK){
}
TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWEA);//enable TWI and ACK
while(!(TWCR & (1<<TWINT)));
uint8_t indoor2 = TWDR;//assign second byte read to variable
if((TWSR & 0xF8) != TW_MR_DATA_ACK){
}
TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);//stop transmission
return ((((indoor1 << 8) + indoor2) >> 5));
}
int main ()
{
uint16_t lm73_temp; //a place to assemble the temperature from the lm73
spi_init(); //initalize SPI
lcd_init(); //initalize LCD (lcd_functions.h)
init_twi(); //initalize TWI (twi_master.h)
lm73_resolution_config();
//set LM73 mode for reading temperature by loading pointer register
//this is done outside of the normal interrupt mode of operation
//load lm73_wr_buf[0] with temperature pointer address
lm73_wr_buf[0] = LM73_PTR_TEMP;
//start the TWI write process (twi_start_wr())
twi_start_wr(LM73_ADDRESS, lm73_wr_buf, 1);
//enable interrupts to allow start_wr to finish
sei();
clear_display(); //clean up the display
while(1){ //main while loop
_delay_ms(100); //tenth second wait
clear_display(); //wipe the display
//read temperature data from LM73 (2 bytes) (twi_start_rd())
twi_start_rd(LM73_ADDRESS, lm73_rd_buf, 2);
_delay_ms(2); //wait for it to finish
//now assemble the two bytes read back into one 16-bit value
lm73_temp = lm73_rd_buf[0]; //save high temperature byte into lm73_temp
lm73_temp <<= 8; //shift it into upper byte
lm73_temp |= lm73_rd_buf[1]; //"OR" in the low temp byte to lm73_temp
itoa(lm73_temp, lcd_string_array, 2); //convert to string in array with itoa() from avr-libc
string2lcd(lcd_string_array); //send the string to LCD (lcd_functions)
} //while
} //main
