Work with temperature sensor DS18B20

ds18b20.c

/**
	ds18b20.c - work with temperature sensor DS18B20
	
	Author:	Vitaiy Zhuk
 */

#include <util/delay.h>
#include "ds18b20.h"

/**
	Write bit \a bit to 1-Wire PIN.
 */
void ds18b20WriteBit(uint8_t bit)
{
	DS18B20_LOW();
	DS18B20_OUTPUT();
	_delay_us(1);
	
	if (bit) {
		DS18B20_INPUT();
	}
	
	_delay_us(60);
	DS18B20_INPUT();
}

/**
	Read bit from 1-Wire PIN
 */
uint8_t ds18b20ReadBit()
{
	uint8_t bit = 0;
	
	DS18B20_LOW();
	DS18B20_OUTPUT();
	_delay_us(1);
	DS18B20_INPUT();
	_delay_us(14);
	
	if (DS18B20_PORT_PIN & (1 << DS18B20_PIN)) {
		bit = 1;
	}
	
	_delay_us(45);
	
	return bit;
}

uint8_t ds18b20Reset()
{
	uint8_t status;
	
	DS18B20_LOW();
	DS18B20_OUTPUT();
	
	_delay_us(480);
	
	DS18B20_INPUT();
	
	_delay_us(60);
	
	status = (DS18B20_PORT_PIN & (1 << DS18B20_PIN));
	
	_delay_us(420);
	
	return status;
}

void ds18b20WriteByte(uint8_t byte)
{
	uint8_t i = 8;
	
	while (i--) {
		ds18b20WriteBit(byte & 1);
		byte >>= 1;
	}
}

uint8_t ds18b20ReadByte()
{
	uint8_t byte = 0, i = 8;
	
	while (i--) {
		byte >>= 1;
		byte |= (ds18b20ReadBit() << 7);
	}
	
	return byte;
}

void ds18b20ReadTemperature(int8_t *temperature)
{
	ds18b20Reset();
	
	ds18b20WriteByte(DS18B20_CMD_SCIPROM);
	ds18b20WriteByte(DS18B20_CMD_CONVERT);
	
	while (!ds18b20ReadBit());
	
	ds18b20Reset();
	
	ds18b20WriteByte(DS18B20_CMD_SCIPROM);
	ds18b20WriteByte(DS18B20_CMD_MEMREAD);
	
	uint8_t secondByte = ds18b20ReadByte();
	uint8_t firstByte = ds18b20ReadByte();
	uint8_t positive = ~(1 & (firstByte >> 4));
	
	temperature[0] |= (firstByte << 4) | (secondByte >> 4);
	temperature[0] &= ~(0b10000000);
	temperature[1] = secondByte & 0b00001111;
	
	if (!positive) {
		temperature[0] ^= 0xFF;
		temperature[1] ^= 0x0F;
	}
}

void ds18b20WriteConfig(uint8_t th, uint8_t tl, uint8_t config)
{
	ds18b20Reset();
	ds18b20WriteByte(DS18B20_CMD_SCIPROM);
	ds18b20WriteByte(DS18B20_CMD_MEMWRITE);
	ds18b20WriteByte(th);
	ds18b20WriteByte(tl);
	ds18b20WriteByte(config);
	ds18b20WriteByte(DS18B20_CMD_MEMWRITE);
}

ds18b20.h

/**
	ds18b20.h - work with temperature sensor DS18B20
	
	Author:	Vitaiy Zhuk
 */

// Data PORT/DDR must be defined
#ifndef DS18B20_DDR
# error "DS18B20_DDR not defined for temp/ds18b20.h"
#endif

#ifndef DS18B20_PORT
# error "DS18B20_PORT not defined for temp/ds18b20.h"
#endif

#ifndef DS18B20_PORT_PIN
# error "DS18B20_PORT_PIN not defined for temp/ds18b29.h"
#endif

#ifndef DS18B20_PIN
# error "DS18B20_PIN not defined for temp/ds18b20.h"
#endif

// Define macros
#define DS18B20_INPUT() DS18B20_DDR &= ~(1 << DS18B20_PIN)
#define DS18B20_OUTPUT() DS18B20_DDR |= (1 << DS18B20_PIN)
#define DS18B20_LOW() DS18B20_PORT &= ~(1 << DS18B20_PIN)
#define DS18B20_HIGH() DS18B20_PORT |= (1 << DS18B20_PIN)

/** ROM COMMANDS **/
#define DS18B20_CMD_SEARCHROM 0xF0
#define DS18B20_CMD_READROM 0x33
#define DS18B20_CMD_MATCHROM 0x55
#define DS18B20_CMD_SCIPROM 0xCC
#define DS18B20_CMD_ALARMSEARCH 0xEC
/** FUNCTIONAL COMMANDS **/
#define DS18B20_CMD_CONVERT 0x44
#define DS18B20_CMD_MEMWRITE 0x4E
#define DS18B20_CMD_MEMREAD 0xBE
#define DS18B20_CMD_MEMCOPY 0x48
#define DS18B20_CMD_RETRYLOAD 0xB8
#define DS18B20_CMD_RPWRSUPPLY 0xB4

// Configurations
#define DS18B20_CONFIG_R1 6
#define DS18B20_CONFIG_R0 5

/**
	Reset sensor
 */
uint8_t ds18b20Reset();

/**
	Write byte \a byte to sensor
 */
void ds18b20WriteByte(uint8_t byte);

/**
	Read byte from sensor
 */
uint8_t ds18b20ReadByte();

/**
	Read temperature.
 */
void ds18b20ReadTemperature(int8_t *temperature);

/**
	Write configuration bytes to DS18B20 memory
	\a th - Alert of temperature high
	\a tl - Alert of temperature low
	\a config - Configuration byte
 */
void ds18b20WriteConfig(uint8_t th, uint8_t tl, uint8_t config);