/*,-----------------------------------------------------------------------------------------.| io/lm75|-----------------------------------------------------------------------------------------| this file supports temperature reading of an i2c temp sensor| - supports LM75 & clones, adjust LM75_DEVICE_ID in config.h !!| - does not check for ACK/NACK/ERROR !|| Author   : {{removed according to contest rules}}|            -> circuitcellar.com avr design contest 2006|            -> Entry #AT2616||-----------------------------------------------------------------------------------------| License:| This program is free software; you can redistribute it and/or modify it under| the terms of the GNU General Public License as published by the Free Software| Foundation; either version 2 of the License, or (at your option) any later| version.| This program is distributed in the hope that it will be useful, but|| WITHOUT ANY WARRANTY;|| without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR| PURPOSE. See the GNU General Public License for more details.|| You should have received a copy of the GNU General Public License along with| this program; if not, write to the Free Software Foundation, Inc., 51| Franklin St, Fifth Floor, Boston, MA 02110, USA|| http://www.gnu.de/gpl-ger.html`-----------------------------------------------------------------------------------------*/#include "lm75.h"#include "main.h"//ACTIVATE DEBUG by editing this file:#include "debug.h"#include <avr/delay.h>#define LM75_READ  1#define LM75_WRITE 0#define LM75_STATE_IDLE            0#define LM75_STATE_DEVICE_ADDRESS  1#define LM75_STATE_WRITE_CMD0      2#define LM75_STATE_START2          3#define LM75_STATE_DEVICE_ADDRESS2 4#define LM75_STATE_DATA_HI         5#define LM75_STATE_DATA_LO         6#define LM75_STATE_STOP            7#define LM75_STATE_ERROR           8#define LM75_ANSWER_START         0x08#define LM75_ANSWER_RESTART       0x10#define LM75_ANSWER_SLAVE_W_ACK   0x18#define LM75_ANSWER_SLAVE_R_ACK   0x40#define LM75_ANSWER_DATA_ACK      0x28#define LM75_ANSWER_DATA_NACK     0x58volatile unsigned char lm75_state;volatile unsigned int lm75_temp_tmp;void lm75_init(void) {	//initialize TWI clock: TWPS = 0 => prescaler = 1 	#if defined(TWPS0)		//has prescaler (mega128 & newer)		TWSR = 0;//0;	#endif	//slow...	TWBR = 20; //f(SCL) = F_CPU / (16+2*TWBR)*4^TWPS)	lm75_state = LM75_STATE_IDLE;	lm75_temp_tmp = (32<<1);}//do a nonblocking read. this function must be called// ? times in order to read a value.// returns 1 if new value measured, otherwise 0unsigned char lm75_nonblocking_temp_read(unsigned char *data){	unsigned char retval = 0;	switch(lm75_state){		//send start cmd & wait for TWI to send it:		case(LM75_STATE_IDLE):			lm75_send_start();			//check for error:			if ((TWSR & 0xF8) != LM75_ANSWER_START)				lm75_state = LM75_STATE_ERROR; 			else				lm75_state = LM75_STATE_DEVICE_ADDRESS;			break;		//send device address:		case(LM75_STATE_DEVICE_ADDRESS):			lm75_send_device_address(LM75_DEVICE_ID | LM75_WRITE);			//check for error:			if ((TWSR & 0xF8) != LM75_ANSWER_SLAVE_W_ACK)				lm75_state = LM75_STATE_ERROR; 			else				lm75_state = LM75_STATE_WRITE_CMD0;			break;		//send "set temp pointer" cmd		case(LM75_STATE_WRITE_CMD0):			lm75_send_byte(0x00);			//check for error:			if ((TWSR & 0xF8) != LM75_ANSWER_DATA_ACK)				lm75_state = LM75_STATE_ERROR; 			else				lm75_state = LM75_STATE_START2;			break;		//send a second start:		case(LM75_STATE_START2):			lm75_send_start();			//check for error:			if ((TWSR & 0xF8) != LM75_ANSWER_RESTART)				lm75_state = LM75_STATE_ERROR; 			else				lm75_state = LM75_STATE_DEVICE_ADDRESS2;			break;		//send address again:		case(LM75_STATE_DEVICE_ADDRESS2):			lm75_send_device_address(LM75_DEVICE_ID | LM75_READ);			//check for error:			if ((TWSR & 0xF8) != LM75_ANSWER_SLAVE_R_ACK)				lm75_state = LM75_STATE_ERROR; 			else				lm75_state = LM75_STATE_DATA_HI;			break;		//read data hi:		case(LM75_STATE_DATA_HI):			lm75_temp_tmp = (lm75_read()<<8);			//check for error:			if ((TWSR & 0xF8) != LM75_ANSWER_DATA_NACK)				lm75_state = LM75_STATE_ERROR; 			else				lm75_state = LM75_STATE_DATA_LO;			break;		//read data lo:		case(LM75_STATE_DATA_LO):			lm75_temp_tmp |= lm75_read();			//is temp negative ? -> convert			if (lm75_temp_tmp&0x8000){				//convert from 2s complement:				lm75_temp_tmp = (0xFFFF-lm75_temp_tmp)|0x8000;			}						//tttt tttt t000 0000 -> 0000 000t tttt tttt			lm75_temp_tmp = lm75_temp_tmp>>7;			//now convert temperature to an 8 bit value.			//-> we are interested in -32.0 to +96.5 degrees			lm75_temp_tmp = lm75_temp_tmp + (32<<1);			//limit range 1:			if (lm75_temp_tmp < 0)				lm75_temp_tmp = 0;			//limit range 2:			if (lm75_temp_tmp >= 255){				lm75_temp_tmp = 255;				return 0;			}/*			//convert to temp vale. 205 = 20.5 °C			//tttt tttt t000 0000 -> 0000 000t tttt tttt			lm75_temp_tmp = lm75_temp_tmp>>7;			//convert to temp vale. 205 = 20.5 °C			(*data) = ((lm75_temp_tmp>>1)&0x007F)*10; 				//add 0.5°C step:			if (lm75_temp_tmp&0x0001)				*data = (*data) + 5;			//is temp negative ?			if (lm75_temp_tmp&0x0100)				*data = -(*data);*/			(*data) = (lm75_temp_tmp)&0xFF;			//success:			retval = 1;			//dont check for error, next state is always stop:		case(LM75_STATE_STOP):		default:			lm75_send_stop();			lm75_state = LM75_STATE_IDLE; 			break;		case(LM75_STATE_ERROR):			#if LM75_DEBUG				softuart_puts_progmem("LM75: error in state ");				softuart_put_uint8(lm75_state);				softuart_puts_progmem(" TWSR=");				softuart_put_uint8(TWSR);				softuart_putnewline();			#endif			lm75_state = LM75_STATE_STOP;	}	return retval;}void lm75_send_start(){	//start cond.	TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);	while (!(TWCR & (1 << TWINT)));}void lm75_send_stop(){	//stop condition	TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);}void lm75_send_device_address(unsigned char addr){	//send device address (including pge offset + write/read flag)	TWDR = addr;	TWCR = (1 << TWINT) | (1 << TWEN);	while (!(TWCR & (1 << TWINT)));}void lm75_send_byte(unsigned char byte){	TWDR = byte;	TWCR = (1 << TWINT) | (1 << TWEN);	while (!(TWCR & (1 << TWINT)));}unsigned char lm75_read(){	//start read transmission	TWCR = (1 << TWINT) | (1 << TWEN);	while (!(TWCR & (1 << TWINT)));	return TWDR;}void lm75_write(unsigned char data){	//load byte to data reg and start transmission	TWDR = data;	TWCR = (1 << TWINT) | (1 << TWEN);	while (!(TWCR & (1 << TWINT)));}/*int lm75_read_temp(){	unsigned int res;	int tmp;	//send start	lm75_send_start();return 0;	//send device address 	lm75_send_device_address(LM75_DEVICE_ID | LM75_WRITE);		//send lm75 pointer cmd for temp	lm75_send_byte(0x00);	//send start	lm75_send_start();	//send device address	lm75_send_device_address(LM75_DEVICE_ID | LM75_READ);		//read data hi:	res = (lm75_read()<<8);		//read data_lo	res |= lm75_read();	//tttt tttt t000 0000 -> 0000 000t tttt tttt	res = res>>7;	//convert to temp vale. 205 = 20.5 °C	tmp = ((res>>1)&0x007F)*10; 		//add 0.5°C step:	if (res&0x0001)		tmp = tmp + 5;	//is temp negative ?	if (res&0x0100)		tmp = -tmp;		//stop	lm75_send_stop();	return tmp;}	*/