Petras Saduikis
Now supports DS18B20 and DS18S20 Maxim/Dallas one-wire thermometer devices. Also supports DS18S20 in 9, 10, 11, and 12 bit resolution modes. 'Use Address' mode now checks if the correct device type is present, and informs the user which device to use. Correct temperature conversion times now used in non-parasitic mode. The device should be placed at least 6 inches (15 cm) from the mbed board in order to accurately read ambient temperature.
DS18B20.cpp@0:01a6a40578c9, 2010-01-03 (annotated)
- Committer:
- snatch59
- Date:
- Sun Jan 03 11:57:31 2010 +0000
- Revision:
- 0:01a6a40578c9
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| snatch59 | 0:01a6a40578c9 | 1 | /* |
| snatch59 | 0:01a6a40578c9 | 2 | * DS18B20. Maxim DS18B20 One-Wire Thermometer. |
| snatch59 | 0:01a6a40578c9 | 3 | * Uses the OneWireCRC library. |
| snatch59 | 0:01a6a40578c9 | 4 | * |
| snatch59 | 0:01a6a40578c9 | 5 | * Copyright (C) <2010> Petras Saduikis <petras@petras.co.uk> |
| snatch59 | 0:01a6a40578c9 | 6 | * |
| snatch59 | 0:01a6a40578c9 | 7 | * This file is part of OneWireThermometer. |
| snatch59 | 0:01a6a40578c9 | 8 | * |
| snatch59 | 0:01a6a40578c9 | 9 | * OneWireThermometer is free software: you can redistribute it and/or modify |
| snatch59 | 0:01a6a40578c9 | 10 | * it under the terms of the GNU General Public License as published by |
| snatch59 | 0:01a6a40578c9 | 11 | * the Free Software Foundation, either version 3 of the License, or |
| snatch59 | 0:01a6a40578c9 | 12 | * (at your option) any later version. |
| snatch59 | 0:01a6a40578c9 | 13 | * |
| snatch59 | 0:01a6a40578c9 | 14 | * OneWireThermometer is distributed in the hope that it will be useful, |
| snatch59 | 0:01a6a40578c9 | 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| snatch59 | 0:01a6a40578c9 | 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| snatch59 | 0:01a6a40578c9 | 17 | * GNU General Public License for more details. |
| snatch59 | 0:01a6a40578c9 | 18 | * |
| snatch59 | 0:01a6a40578c9 | 19 | * You should have received a copy of the GNU General Public License |
| snatch59 | 0:01a6a40578c9 | 20 | * along with OneWireThermometer. If not, see <http://www.gnu.org/licenses/>. |
| snatch59 | 0:01a6a40578c9 | 21 | */ |
| snatch59 | 0:01a6a40578c9 | 22 | |
| snatch59 | 0:01a6a40578c9 | 23 | #include "DS18B20.h" |
| snatch59 | 0:01a6a40578c9 | 24 | #include "DebugTrace.h" |
| snatch59 | 0:01a6a40578c9 | 25 | |
| snatch59 | 0:01a6a40578c9 | 26 | DebugTrace pc_ds18B20(ON, TO_SERIAL); |
| snatch59 | 0:01a6a40578c9 | 27 | |
| snatch59 | 0:01a6a40578c9 | 28 | DS18B20::DS18B20(bool crcOn, bool useAddr, bool parasitic, PinName pin) : |
| snatch59 | 0:01a6a40578c9 | 29 | OneWireThermometer(crcOn, useAddr, parasitic, pin, DS18B20_ID) |
| snatch59 | 0:01a6a40578c9 | 30 | { |
| snatch59 | 0:01a6a40578c9 | 31 | } |
| snatch59 | 0:01a6a40578c9 | 32 | |
| snatch59 | 0:01a6a40578c9 | 33 | void DS18B20::setResolution(eResolution resln) |
| snatch59 | 0:01a6a40578c9 | 34 | { |
| snatch59 | 0:01a6a40578c9 | 35 | // as the write to the configuration register involves a write to the |
| snatch59 | 0:01a6a40578c9 | 36 | // high and low alarm bytes, need to read these registers first |
| snatch59 | 0:01a6a40578c9 | 37 | // and copy them back on the write |
| snatch59 | 0:01a6a40578c9 | 38 | |
| snatch59 | 0:01a6a40578c9 | 39 | BYTE read_data[THERMOM_SCRATCHPAD_SIZE]; |
| snatch59 | 0:01a6a40578c9 | 40 | BYTE write_data[ALARM_CONFIG_SIZE]; |
| snatch59 | 0:01a6a40578c9 | 41 | |
| snatch59 | 0:01a6a40578c9 | 42 | if (readAndValidateData(read_data)) |
| snatch59 | 0:01a6a40578c9 | 43 | { |
| snatch59 | 0:01a6a40578c9 | 44 | // copy alarm and config data to write data |
| snatch59 | 0:01a6a40578c9 | 45 | for (int k = 2; k < 5; k++) |
| snatch59 | 0:01a6a40578c9 | 46 | { |
| snatch59 | 0:01a6a40578c9 | 47 | write_data[k - 2] = read_data[k]; |
| snatch59 | 0:01a6a40578c9 | 48 | } |
| snatch59 | 0:01a6a40578c9 | 49 | int config = write_data[2]; |
| snatch59 | 0:01a6a40578c9 | 50 | config &= 0x9F; |
| snatch59 | 0:01a6a40578c9 | 51 | config ^= (resln << 5); |
| snatch59 | 0:01a6a40578c9 | 52 | write_data[2] = config; |
| snatch59 | 0:01a6a40578c9 | 53 | |
| snatch59 | 0:01a6a40578c9 | 54 | resetAndAddress(); |
| snatch59 | 0:01a6a40578c9 | 55 | oneWire.writeByte(WRITESCRATCH); |
| snatch59 | 0:01a6a40578c9 | 56 | for (int k = 0; k < 3; k++) |
| snatch59 | 0:01a6a40578c9 | 57 | { |
| snatch59 | 0:01a6a40578c9 | 58 | oneWire.writeByte(write_data[k]); |
| snatch59 | 0:01a6a40578c9 | 59 | } |
| snatch59 | 0:01a6a40578c9 | 60 | |
| snatch59 | 0:01a6a40578c9 | 61 | // remember it so we can use the correct delay in reading the temperature |
| snatch59 | 0:01a6a40578c9 | 62 | // for parasitic power |
| snatch59 | 0:01a6a40578c9 | 63 | resolution = resln; |
| snatch59 | 0:01a6a40578c9 | 64 | } |
| snatch59 | 0:01a6a40578c9 | 65 | } |
| snatch59 | 0:01a6a40578c9 | 66 | |
| snatch59 | 0:01a6a40578c9 | 67 | float DS18B20::calculateTemperature(BYTE* data) |
| snatch59 | 0:01a6a40578c9 | 68 | { |
| snatch59 | 0:01a6a40578c9 | 69 | bool signBit = false; |
| snatch59 | 0:01a6a40578c9 | 70 | if (data[TEMPERATURE_MSB] & 0x80) signBit = true; |
| snatch59 | 0:01a6a40578c9 | 71 | |
| snatch59 | 0:01a6a40578c9 | 72 | int read_temp = (data[TEMPERATURE_MSB] << 8) + data[TEMPERATURE_LSB]; |
| snatch59 | 0:01a6a40578c9 | 73 | if (signBit) |
| snatch59 | 0:01a6a40578c9 | 74 | { |
| snatch59 | 0:01a6a40578c9 | 75 | read_temp = (read_temp ^ 0xFFFF) + 1; // two's complement |
| snatch59 | 0:01a6a40578c9 | 76 | read_temp *= -1; |
| snatch59 | 0:01a6a40578c9 | 77 | } |
| snatch59 | 0:01a6a40578c9 | 78 | |
| snatch59 | 0:01a6a40578c9 | 79 | int resolution = (data[CONFIG_REG_BYTE] & 0x60) >> 5; // mask off bits 6,5 and move to 1,0 |
| snatch59 | 0:01a6a40578c9 | 80 | switch (resolution) |
| snatch59 | 0:01a6a40578c9 | 81 | { |
| snatch59 | 0:01a6a40578c9 | 82 | case nineBit: // 0.5 deg C increments |
| snatch59 | 0:01a6a40578c9 | 83 | read_temp &= 0xFFF8; // bits 2,1,0 are undefined |
| snatch59 | 0:01a6a40578c9 | 84 | pc_ds18B20.traceOut("9 bit resolution ...\r\n"); |
| snatch59 | 0:01a6a40578c9 | 85 | break; |
| snatch59 | 0:01a6a40578c9 | 86 | case tenBit: // 0.25 deg C increments |
| snatch59 | 0:01a6a40578c9 | 87 | read_temp &= 0xFFFC; // bits 1,0 are undefined |
| snatch59 | 0:01a6a40578c9 | 88 | pc_ds18B20.traceOut("10 bit resolution ...\r\n"); |
| snatch59 | 0:01a6a40578c9 | 89 | break; |
| snatch59 | 0:01a6a40578c9 | 90 | case elevenBit: // 0.125 deg C increments |
| snatch59 | 0:01a6a40578c9 | 91 | read_temp &= 0xFFFE; // bit 0 is undefined |
| snatch59 | 0:01a6a40578c9 | 92 | pc_ds18B20.traceOut("11 bit resolution ...\r\n"); |
| snatch59 | 0:01a6a40578c9 | 93 | break; |
| snatch59 | 0:01a6a40578c9 | 94 | case twelveBit: // 0.0625 deg C increments |
| snatch59 | 0:01a6a40578c9 | 95 | pc_ds18B20.traceOut("12 bit resolution ...\r\n"); |
| snatch59 | 0:01a6a40578c9 | 96 | break; |
| snatch59 | 0:01a6a40578c9 | 97 | } |
| snatch59 | 0:01a6a40578c9 | 98 | float realTemp = (float)read_temp/16 ; |
| snatch59 | 0:01a6a40578c9 | 99 | |
| snatch59 | 0:01a6a40578c9 | 100 | pc_ds18B20.traceOut("TEMP_READ/REAL TEMP: %f \r\n", realTemp); |
| snatch59 | 0:01a6a40578c9 | 101 | |
| snatch59 | 0:01a6a40578c9 | 102 | return realTemp; |
| snatch59 | 0:01a6a40578c9 | 103 | } |