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/*
* spreadspace avr utils - usb-1wire example
*
*
* Copyright (C) 2013 Bernhard Tittelbach <xro@realraum.at>
* based on code from:
* http://www.pjrc.com/teensy/td_libs_OneWire.html
*
* This file is part of spreadspace avr utils.
*
* spreadspace avr utils 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 3 of the License, or
* any later version.
*
* spreadspace avr utils 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 spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
*/
#include "ds1820.h"
#include "onewire.h"
#include "util/delay.h"
uint8_t owi_ds1820_addr_[MAX_OWI_DEVICES][8];
uint8_t num_ds1820_found_;
uint8_t ds1820_discover(void)
{
uint8_t d=0;
num_ds1820_found_ = 0;
if (! owi_reset()) //if no devices on bus, return now
return 0;
owi_reset_search();
_delay_ms(250);
//Search only for DS1820 temp sensors
owi_target_search(DS1820_FAMILY_ID);
while ( owi_search(owi_ds1820_addr_[ d ]))
{
d++;
if ( d >= MAX_OWI_DEVICES)
break;
}
num_ds1820_found_ = d;
return num_ds1820_found_;
}
void ds1820_set_resolution(uint8_t d, uint8_t bits)
{
uint8_t resolution;
if (d >= num_ds1820_found_ || bits < 9 || bits > 12)
return;
owi_reset();
owi_select(owi_ds1820_addr_[d]);
owi_write(DS1820_WRITE_SCRATCHPAD, 0);
owi_write(0xFF, 0);
owi_write(0x7F, 0);
resolution = (bits - 9) << 5;
owi_write(resolution | 0x1F, 0);
}
void ds1820_start_measuring(uint8_t d)
{
owi_reset();
owi_select(owi_ds1820_addr_[d]);
owi_write(DS1820_START_CONVERSION, 1);
}
uint16_t ds1820_get_conversion_time_ms(uint8_t bits)
{
switch (bits)
{
case 9: return DS1820_TCONV_MS_9BITS;
case 10: return DS1820_TCONV_MS_10BITS;
case 11: return DS1820_TCONV_MS_11BITS;
default: return DS1820_TCONV_MS_12BITS;
}
}
void ds1820_wait_conversion_time(uint8_t bits)
{
switch (bits)
{
case 9: _delay_ms(DS1820_TCONV_MS_9BITS); break;
case 10: _delay_ms(DS1820_TCONV_MS_10BITS); break;
case 11: _delay_ms(DS1820_TCONV_MS_11BITS); break;
default: _delay_ms(DS1820_TCONV_MS_12BITS); break;
}
}
int16_t ds1820_read_temperature(uint8_t d)
{
uint8_t data[9];
int16_t raw = 0;
uint8_t type_s=0;
uint8_t cfg, i;
owi_reset();
owi_select(owi_ds1820_addr_[d]);
owi_write(DS1820_READ_SCRATCHPAD, 0); // Read Scratchpad
for (i = 0; i < 9; i++) { // we need 9 bytes
data[i] = owi_read();
}
#if (ONEWIRE_CRC == 1)
uint8_t crc_result = owi_crc8(data,8);
if (crc_result != data[8])
return DS1820_ERROR;
#endif
// the first ROM byte indicates which chip
switch (owi_ds1820_addr_[d][0])
{
case 0x10:
type_s = 1;
break;
case 0x28:
case 0x22:
type_s = 0;
break;
default:
break;
}
// Convert the data to actual temperature
// because the result is a 16 bit signed integer, it should
// be stored to an "int16_t" type, which is always 16 bits
// even when compiled on a 32 bit processor.
raw = (data[1] << 8) | data[0];
if (type_s)
{
raw = raw << 3; // 9 bit resolution default
if (data[7] == 0x10) {
// "count remain" gives full 12 bit resolution
raw = (raw & 0xFFF0) + 12 - data[6];
}
} else {
cfg = (data[4] & 0x60);
// at lower res, the low bits are undefined, so let's zero them
if (cfg == DS1820_RESOLUTION_9BITS)
raw = raw & ~7; // 9 bit resolution, 93.75 ms
else if (cfg == DS1820_RESOLUTION_10BITS)
raw = raw & ~3; // 10 bit res, 187.5 ms
else if (cfg == DS1820_RESOLUTION_11BITS)
raw = raw & ~1; // 11 bit res, 375 ms
//// default is 12 bit resolution, 750 ms conversion time
}
return raw;
}
float ds1820_raw_temp_to_celsius(int16_t t)
{
if ( t == DS1820_ERROR )
return DS1820_ERROR;
else
return ((float) t) / 16.0;
}
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