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Diffstat (limited to 'software/lib/ds1820.c')
| -rw-r--r-- | software/lib/ds1820.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/software/lib/ds1820.c b/software/lib/ds1820.c new file mode 100644 index 0000000..ca1ff16 --- /dev/null +++ b/software/lib/ds1820.c @@ -0,0 +1,167 @@ +/* + * 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; +} |