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ds18b20.c
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ds18b20.c
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/*
CodeVisionAVR C Compiler
(C) 1998-2007 Pavel Haiduc, HP InfoTech S.R.L.
Dallas Semiconductor DS18B20 1 Wire bus temperature sensor functions
*/
#include <delay.h>
#include <ds18b20.h>
struct __ds18b20_scratch_pad_struct __ds18b20_scratch_pad;
// temp. conversion time [ms] depending on the resolution
static flash int conv_delay[4]={100,200,400,800};
// valid temp. bit mask depending on the resolution
static flash unsigned bit_mask[4]={0xFFF8,0xFFFC,0xFFFE,0xFFFF};
unsigned char ds18b20_select(unsigned char *addr)
{
unsigned char i;
if (w1_init() == 0)
{
return 0;
}
if (addr)
{
w1_write(0x55);
i = 0;
do
{
w1_write(*(addr++));
}
while (++i < 8);
}
else
{
w1_write(0xcc);
}
return 1;
}
unsigned char ds18b20_read_spd(unsigned char *addr)
{
unsigned char i;
unsigned char *p;
if (ds18b20_select(addr)==0)
{
return 0;
}
w1_write(0xbe);
i = 0;
p = (char*) &__ds18b20_scratch_pad;
do
{
*(p++) = w1_read();
}
while (++i < 9);
return !w1_dow_crc8(&__ds18b20_scratch_pad, 9);
}
// Запросить данные о температуре и получить их через некоторое время.
float ds18b20_temperature(unsigned char *addr)
{
unsigned char resolution;
if (ds18b20_read_spd(addr) == 0)
{
return -9999;
}
resolution = (__ds18b20_scratch_pad.conf_register >> 5) & 3;
if (ds18b20_select(addr) == 0)
{
return -9999;
}
w1_write(0x44);
delay_ms(conv_delay[resolution]);
if (ds18b20_read_spd(addr)==0)
{
return -9999;
}
w1_init();
return (*((int *) &__ds18b20_scratch_pad.temp_lsb) & ((int) bit_mask[resolution]))*0.0625;
}
// Запросить данные о температуре.
// В зависимости от разрешения данныех потребуеться 100,200,400,800 ms.
int ds18b20_request_temperature(unsigned char *addr)
{
if (ds18b20_read_spd(addr) == 0)
{
return 0;
}
if (ds18b20_select(addr) == 0)
{
return 0;
}
w1_write(0x44);
return 1;
}
// Получить подготовленные данные.
float ds18b20_get_temperature(unsigned char *addr)
{
unsigned char resolution;
resolution = (__ds18b20_scratch_pad.conf_register >> 5) & 3;
if (ds18b20_read_spd(addr)==0)
{
return -9999;
}
w1_init();
return (*((int *) &__ds18b20_scratch_pad.temp_lsb) & ((int) bit_mask[resolution]))*0.0625;
}
// Инициализация устройства.
unsigned char ds18b20_init(unsigned char *addr, signed char temp_low, signed char temp_high, unsigned char resolution)
{
if (ds18b20_select(addr) == 0)
{
return 0;
}
resolution=(resolution << 5) | 0x1f;
w1_write(0x4e);
w1_write(temp_high);
w1_write(temp_low);
w1_write(resolution);
if (ds18b20_read_spd(addr) == 0)
{
return 0;
}
if ((__ds18b20_scratch_pad.temp_low != temp_low) || (__ds18b20_scratch_pad.temp_high != temp_high) || (__ds18b20_scratch_pad.conf_register!=resolution))
{
return 0;
}
if (ds18b20_select(addr) == 0)
{
return 0;
}
w1_write(0x48);
delay_ms(15);
return w1_init();
}