Tony Mudd
Program to read the temperature from multiple DS18B20 sensors on the same pin. The original library/code came from Petras Saduikis (see http://mbed.org/users/snatch59/programs/OneWireCRC/gpdz56), but I've modified it to remember the address of multiple sensors all connected to the same data pin. My sample program displays the temperature of each device in turn. If you want to see more of what's going on behind the scenes turn on the debug by setting DebugTrace pc(OFF, TO_SERIAL); to ON (instead of OFF) in the couple of places it's used - it will log the device addresses as they are found etc. The addresses are set in the devices at the factory - I don't think they can be changed, the search always seems to find them in the same order, but this won't be anything to do with the way you've plugged them in. I've had a play with up to 7 sensors (the code has a limit of 10 hardwired in it, but this would be easy to change)
Diff: OneWireDefs.h
- Revision:
- 0:fb8b6da96a8b
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/OneWireDefs.h Sun Jul 17 15:56:49 2011 +0000
@@ -0,0 +1,66 @@
+/*
+* OneWireCRC. This is a port to mbed of Jim Studt's Adruino One Wire
+* library.
+*
+* Copyright (C) <2009> Petras Saduikis <petras@petras.co.uk>
+*
+* This file is part of OneWireCRC.
+*
+* OneWireCRC 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
+* (at your option) any later version.
+*
+* OneWireCRC 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 OneWireCRC. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef SNATCH59_ONEWIREDEFS_H
+#define SNATCH59_ONEWIREDEFS_H
+
+// device ids
+#define DS18B20_ID 0x28
+#define DS18S20_ID 0x10
+
+#define ALARM_CONFIG_SIZE 3
+#define THERMOM_SCRATCHPAD_SIZE 9
+#define THERMOM_CRC_BYTE 8
+#define ADDRESS_SIZE 8
+#define ADDRESS_CRC_BYTE 7
+
+// One Wire command codes
+#define OVERDRIVE_SKIP 0x3C
+// ROM commands
+#define SEARCH_ROM 0xF0
+#define READ_ROM 0x33
+#define MATCH_ROM 0x55
+#define SKIP_ROM 0xCC
+#define ALARM_SEARCH 0xEC
+// Functions Commnds
+#define CONVERT 0x44
+#define WRITESCRATCH 0x4E
+#define READSCRATCH 0xBE
+#define COPYSCRATCH 0x48
+#define RECALLE2 0xB8
+#define READPOWERSUPPLY 0xB4
+
+// temperature read resolutions
+enum eResolution {nineBit = 0, tenBit, elevenBit, twelveBit};
+const int CONVERSION_TIME[] = {94, 188, 375, 750}; // milli-seconds
+
+// DS18B20/DS18S20 related
+#define TEMPERATURE_LSB 0
+#define TEMPERATURE_MSB 1
+#define HIGH_ALARM_BYTE 2
+#define LOW_ALARM_BYTE 3
+#define CONFIG_REG_BYTE 4
+#define CONFIG_READ_END 5
+#define COUNT_REMAIN_BYTE 6
+#define COUNT_PER_DEG_BYTE 7
+
+#endif