DS18B20

Dependents:   DS1820_HelloWorld

Files at this revision

API Documentation at this revision

Comitter:
jack__zen
Date:
Wed Sep 06 05:35:15 2017 +0000
Commit message:
onewire

Changed in this revision

OneWireCRC.cpp Show annotated file Show diff for this revision Revisions of this file
OneWireCRC.h Show annotated file Show diff for this revision Revisions of this file
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diff -r 000000000000 -r a47e8ec71a4e OneWireCRC.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OneWireCRC.cpp	Wed Sep 06 05:35:15 2017 +0000
@@ -0,0 +1,459 @@
+/*
+* OneWireCRC. This is a port to mbed of Jim Studt's Adruino One Wire
+* library. Please see additional copyrights below this one, including
+* references to other copyrights.
+*
+* 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/>.
+*/
+/*
+Copyright (c) 2007, Jim Studt
+
+Updated to work with arduino-0008 and to include skip() as of
+2007/07/06. --RJL20
+
+Modified to calculate the 8-bit CRC directly, avoiding the need for
+the 256-byte lookup table to be loaded in RAM.  Tested in arduino-0010
+-- Tom Pollard, Jan 23, 2008
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Much of the code was inspired by Derek Yerger's code, though I don't
+think much of that remains.  In any event that was..
+    (copyleft) 2006 by Derek Yerger - Free to distribute freely.
+
+The CRC code was excerpted and inspired by the Dallas Semiconductor 
+sample code bearing this copyright.
+//---------------------------------------------------------------------------
+// Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
+// OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+//
+// Except as contained in this notice, the name of Dallas Semiconductor
+// shall not be used except as stated in the Dallas Semiconductor
+// Branding Policy.
+//--------------------------------------------------------------------------
+*/
+
+#include "OneWireCRC.h"
+#include "OneWireDefs.h"
+
+// recommended data sheet timings in micro seconds
+const int standardT[] = {6, 64, 60, 10, 9, 55, 0, 480, 70, 410};
+const int overdriveT[] = {1.5, 7.5, 7.5, 2.5, 0.75, 7, 2.5, 70, 8.5, 40};
+
+OneWireCRC::OneWireCRC(PinName oneWire, eSpeed speed) : oneWirePort(oneWire)
+{
+    if (STANDARD == speed) timing = standardT;   
+    else  timing = overdriveT;  // overdrive
+    
+    resetSearch();    // reset address search state
+}
+
+// Generate a 1-wire reset, return 1 if no presence detect was found,
+// return 0 otherwise.
+// (NOTE: does not handle alarm presence from DS2404/DS1994)
+int OneWireCRC::reset() 
+{
+    
+    BYTE result = 0;    // sample presence pulse result
+        
+    wait_us(timing[6]);
+    oneWirePort.output();
+    oneWirePort = 0;
+    wait_us(timing[7]);
+    oneWirePort.input();
+    wait_us(timing[8]);
+    result = !(oneWirePort & 0x01);
+    wait_us(timing[9]);
+    
+    return result;
+}
+
+//
+// Write a bit. Port and bit is used to cut lookup time and provide
+// more certain timing.
+//
+void OneWireCRC::writeBit(int bit)
+{
+    bit = bit & 0x01;
+    
+    if (bit)
+    {
+        // Write '1' bit
+        oneWirePort.output();
+        oneWirePort = 0;
+        wait_us(timing[0]);
+        oneWirePort.input();
+        wait_us(timing[1]);
+    }
+    else
+    {
+        // Write '0' bit
+        oneWirePort.output();
+        oneWirePort = 0;
+        wait_us(timing[2]);
+        oneWirePort.input();
+        wait_us(timing[3]);
+    }
+}
+
+//
+// Read a bit. Port and bit is used to cut lookup time and provide
+// more certain timing.
+//
+int OneWireCRC::readBit() 
+{
+    BYTE result;
+    
+    oneWirePort.output();
+    oneWirePort = 0;
+    wait_us(timing[0]);
+    oneWirePort.input();
+    wait_us(timing[4]);
+    result = oneWirePort & 0x01;
+    wait_us(timing[5]);
+       
+    return result;
+}
+
+//
+// Write a byte. The writing code uses the active drivers to raise the
+// pin high, if you need power after the write (e.g. DS18S20 in
+// parasite power mode) then set 'power' to 1, otherwise the pin will
+// go tri-state at the end of the write to avoid heating in a short or
+// other mishap.
+//
+void OneWireCRC::writeByte(int data) 
+{
+    // Loop to write each bit in the byte, LS-bit first
+    for (int loop = 0; loop < 8; loop++)
+    {
+        writeBit(data & 0x01);
+        
+        // shift the data byte for the next bit
+        data >>= 1;
+    }
+}
+
+//
+// Read a byte
+//
+int OneWireCRC::readByte() 
+{
+    int result = 0;
+    
+    for (int loop = 0; loop < 8; loop++)
+    {
+        // shift the result to get it ready for the next bit
+        result >>= 1;
+        
+        // if result is one, then set MS bit
+        if (readBit()) result |= 0x80;
+    }
+    
+    return result;
+}
+
+int OneWireCRC::touchByte(int data)
+{
+    int result = 0;
+    
+    for (int loop = 0; loop < 8; loop++)
+    {
+        // shift the result to get it ready for the next bit
+        result >>= 1;
+        
+        // If sending a '1' then read a bit else write a '0'
+        if (data & 0x01)
+        {
+            if (readBit()) result |= 0x80;
+        }
+        else writeBit(0);
+        
+        // shift the data byte for the next bit
+        data >>= 1;
+    }
+    
+    return result;
+}
+
+void OneWireCRC::block(BYTE* data, int data_len)
+{
+    for (int loop = 0; loop < data_len; loop++)
+    {
+        data[loop] = touchByte(data[loop]);
+    }
+}
+
+int OneWireCRC::overdriveSkip(BYTE* data, int data_len)
+{
+    // set the speed to 'standard'
+    timing = standardT;
+    
+    // reset all devices
+    if (reset()) return 0;    // if no devices found
+    
+    // overdrive skip command
+    writeByte(OVERDRIVE_SKIP);
+    
+    // set the speed to 'overdrive'
+    timing = overdriveT;
+    
+    // do a 1-Wire reset in 'overdrive' and return presence result
+    return reset();
+}
+
+//
+// Do a ROM select
+//
+void OneWireCRC::matchROM(BYTE rom[8])
+{
+    writeByte(MATCH_ROM);         // Choose ROM
+
+    for(int i = 0; i < 8; i++) writeByte(rom[i]);
+}
+
+//
+// Do a ROM skip
+//
+void OneWireCRC::skipROM()
+{
+    writeByte(SKIP_ROM);         // Skip ROM
+}
+
+//
+// You need to use this function to start a search again from the beginning.
+// You do not need to do it for the first search, though you could.
+//
+void OneWireCRC::resetSearch()
+{
+    searchJunction = -1;
+    searchExhausted = false;
+    for (int i = 0; i < 8; i++) 
+    {
+        address[i] = 0;
+    }
+}
+
+//
+// Perform a search. If this function returns a '1' then it has
+// enumerated the next device and you may retrieve the ROM from the
+// OneWire::address variable. If there are no devices, no further
+// devices, or something horrible happens in the middle of the
+// enumeration then a 0 is returned.  If a new device is found then
+// its address is copied to newAddr.  Use OneWire::reset_search() to
+// start over.
+// 
+BYTE OneWireCRC::search(BYTE* newAddr)
+{
+    BYTE i;
+    int lastJunction = -1;
+    BYTE done = 1;
+    
+    if (searchExhausted) return 0;
+    
+    if (!reset()) return 0;
+
+    writeByte(SEARCH_ROM);
+    
+    for(i = 0; i < 64; i++) 
+    {
+        BYTE a = readBit( );
+        BYTE nota = readBit( );
+        BYTE ibyte = i/8;
+        BYTE ibit = 1 << (i & 7);
+    
+        // I don't think this should happen, this means nothing responded, but maybe if
+        // something vanishes during the search it will come up.
+        if (a && nota) return 0;  
+        
+        if (!a && !nota)
+        {
+            if (i == searchJunction) 
+            {
+                // this is our time to decide differently, we went zero last time, go one.
+                a = 1;
+                searchJunction = lastJunction;
+            } 
+            else if (i < searchJunction) 
+            {
+                // take whatever we took last time, look in address
+                if (address[ibyte] & ibit) a = 1;
+                else 
+                {
+                    // Only 0s count as pending junctions, we've already exhasuted the 0 side of 1s
+                    a = 0;
+                    done = 0;
+                    lastJunction = i;
+                }
+            } 
+            else 
+            {
+                // we are blazing new tree, take the 0
+                a = 0;
+                searchJunction = i;
+                done = 0;
+            }
+            lastJunction = i;
+        }
+        
+        if (a) address[ibyte] |= ibit;
+        else address[ibyte] &= ~ibit;
+    
+        writeBit(a);
+    }
+    
+    if (done) searchExhausted = true;
+    
+    for (i = 0; i < 8; i++) newAddr[i] = address[i];
+    
+    return 1;  
+}
+
+// The 1-Wire CRC scheme is described in Maxim Application Note 27:
+// "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
+//
+
+#if ONEWIRE_CRC8_TABLE
+// This table comes from Dallas sample code where it is freely reusable, 
+// though Copyright (C) 2000 Dallas Semiconductor Corporation
+static BYTE dscrc_table[] = 
+{
+      0, 94,188,226, 97, 63,221,131,194,156,126, 32,163,253, 31, 65,
+    157,195, 33,127,252,162, 64, 30, 95,  1,227,189, 62, 96,130,220,
+     35,125,159,193, 66, 28,254,160,225,191, 93,  3,128,222, 60, 98,
+    190,224,  2, 92,223,129, 99, 61,124, 34,192,158, 29, 67,161,255,
+     70, 24,250,164, 39,121,155,197,132,218, 56,102,229,187, 89,  7,
+    219,133,103, 57,186,228,  6, 88, 25, 71,165,251,120, 38,196,154,
+    101, 59,217,135,  4, 90,184,230,167,249, 27, 69,198,152,122, 36,
+    248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91,  5,231,185,
+    140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
+     17, 79,173,243,112, 46,204,146,211,141,111, 49,178,236, 14, 80,
+    175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
+     50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
+    202,148,118, 40,171,245, 23, 73,  8, 86,180,234,105, 55,213,139,
+     87,  9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
+    233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
+    116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107, 53};
+
+//
+// Compute a Dallas Semiconductor 8 bit CRC. These show up in the ROM
+// and the registers.  (note: this might better be done without the
+// table, it would probably be smaller and certainly fast enough
+// compared to all those delayMicrosecond() calls.  But I got
+// confused, so I use this table from the examples.)  
+//
+BYTE OneWireCRC::crc8(BYTE* addr, BYTE len)
+{
+    BYTE i;
+    BYTE crc = 0;
+    
+    for (i = 0; i < len; i++)
+    {
+        crc  = dscrc_table[crc ^ addr[i] ];
+    }
+    
+    return crc;
+}
+#else
+//
+// Compute a Dallas Semiconductor 8 bit CRC directly. 
+//
+BYTE OneWireCRC::crc8(BYTE* addr, BYTE len)
+{
+    BYTE i, j;
+    BYTE crc = 0;
+    
+    for (i = 0; i < len; i++) 
+    {
+        BYTE inbyte = addr[i];
+        for (j = 0; j < 8; j++) 
+        {
+            BYTE mix = (crc ^ inbyte) & 0x01;
+            crc >>= 1;
+            if (mix) crc ^= 0x8C;
+            inbyte >>= 1;
+        }
+    }
+    
+    return crc;
+}
+#endif
+
+static short oddparity[16] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };
+
+//
+// Compute a Dallas Semiconductor 16 bit CRC. I have never seen one of
+// these, but here it is.
+//
+unsigned short OneWireCRC::crc16(unsigned short* data, unsigned short len)
+{
+    unsigned short i;
+    unsigned short crc = 0;
+    
+    for ( i = 0; i < len; i++) 
+    {
+        unsigned short cdata = data[len];
+    
+        cdata = (cdata ^ (crc & 0xff)) & 0xff;
+        crc >>= 8;
+    
+        if (oddparity[cdata & 0xf] ^ oddparity[cdata >> 4]) crc ^= 0xc001;
+    
+        cdata <<= 6;
+        crc ^= cdata;
+        cdata <<= 1;
+        crc ^= cdata;
+    }
+    
+    return crc;
+}
+
diff -r 000000000000 -r a47e8ec71a4e OneWireCRC.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OneWireCRC.h	Wed Sep 06 05:35:15 2017 +0000
@@ -0,0 +1,138 @@
+/*
+* OneWireCRC. This is a port to mbed of Jim Studt's Adruino One Wire
+* library. Please see additional copyrights below this one, including
+* references to other copyrights.
+*
+* 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/>.
+*/
+/*
+Copyright (c) 2007, Jim Studt
+
+Updated to work with arduino-0008 and to include skip() as of
+2007/07/06. --RJL20
+
+Modified to calculate the 8-bit CRC directly, avoiding the need for
+the 256-byte lookup table to be loaded in RAM.  Tested in arduino-0010
+-- Tom Pollard, Jan 23, 2008
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Much of the code was inspired by Derek Yerger's code, though I don't
+think much of that remains.  In any event that was..
+    (copyleft) 2006 by Derek Yerger - Free to distribute freely.
+
+The CRC code was excerpted and inspired by the Dallas Semiconductor 
+sample code bearing this copyright.
+*/
+//---------------------------------------------------------------------------
+// Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
+// OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+//
+// Except as contained in this notice, the name of Dallas Semiconductor
+// shall not be used except as stated in the Dallas Semiconductor
+// Branding Policy.
+//--------------------------------------------------------------------------
+
+#ifndef SNATCH59_ONEWIRECRC_H
+#define SNATCH59_ONEWIRECRC_H
+
+#include <mbed.h>
+
+// Select the table-lookup method of computing the 8-bit CRC by setting this to 1
+#ifndef ONEWIRE_CRC8_TABLE
+#define ONEWIRE_CRC8_TABLE 1
+#endif
+
+typedef unsigned char BYTE;    // used to be uint8_t : something a byte wide, whatever ....
+
+enum eSpeed {OVERDRIVE, STANDARD};
+
+class OneWireCRC
+{
+public:
+    OneWireCRC(PinName oneWire, eSpeed);
+    
+    // reset, read, write functions
+    int reset();
+    void writeByte(int data);
+    int readByte();
+    int touchByte(int data);
+    void block(BYTE* data, int data_len);
+    int overdriveSkip(BYTE* data, int data_len);
+    
+    // address functions
+    void matchROM(BYTE rom[8]);
+    void skipROM();
+
+    // address search functions
+    void resetSearch();
+    BYTE search(BYTE* newAddr);
+
+    // CRC check functions
+    static BYTE crc8(BYTE* addr, BYTE len);
+    static unsigned short crc16(unsigned short* data, unsigned short len);
+
+private:
+    const int* timing;
+    
+    BYTE address[8];
+    int searchJunction;        // so we can set to it -1 somewhere
+    bool searchExhausted;
+    
+    DigitalInOut oneWirePort;
+    
+    // read/write bit functions
+    void writeBit(int bit);
+    int readBit();
+};
+
+#endif
diff -r 000000000000 -r a47e8ec71a4e OneWireDefs.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OneWireDefs.h	Wed Sep 06 05:35:15 2017 +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
diff -r 000000000000 -r a47e8ec71a4e OneWireThermometer.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OneWireThermometer.cpp	Wed Sep 06 05:35:15 2017 +0000
@@ -0,0 +1,167 @@
+/*
+* OneWireThermometer. Base class for Maxim One-Wire Thermometers. 
+* Uses the OneWireCRC library.
+*
+* Copyright (C) <2010> Petras Saduikis <petras@petras.co.uk>
+*
+* This file is part of OneWireThermometer.
+*
+* OneWireThermometer 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.
+* 
+* OneWireThermometer 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 OneWireThermometer.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "OneWireThermometer.h"
+#include "OneWireDefs.h"
+#include "DebugTrace.h"
+
+DebugTrace pc(ON, TO_SERIAL);
+
+// constructor specifies standard speed for the 1-Wire comms
+OneWireThermometer::OneWireThermometer(bool crcOn, bool useAddr, bool parasitic, PinName pin, int device_id) :
+    useCRC(crcOn), useAddress(useAddr), useParasiticPower(parasitic), 
+    oneWire(pin, STANDARD), deviceId(device_id), resolution(twelveBit)
+{
+    // NOTE: the power-up resolution of a DS18B20 is 12 bits. The DS18S20's resolution is always
+    // 9 bits + enhancement, but we treat the DS18S20 as fixed to 12 bits for calculating the
+    // conversion time Tconv.
+}
+
+bool OneWireThermometer::initialize()
+{
+    // get the device address for use in selectROM() when reading the temperature
+    // - not really needed except for device validation if using skipROM()
+    if (useAddress)
+    {
+        pc.traceOut("\r\n");
+        pc.traceOut("New Scan\r\n");
+
+        oneWire.resetSearch();    
+        if (!oneWire.search(address))   // search for 1-wire device address
+        {            
+            pc.traceOut("No more addresses.\r\n");
+            wait(2);
+            return false;
+        }
+
+        pc.traceOut("Address = ");
+        for (int i = 0; i < ADDRESS_SIZE; i++) 
+        {
+            pc.traceOut("%x ", (int)address[i]);
+        }
+        pc.traceOut("\r\n");
+        
+        if (OneWireCRC::crc8(address, ADDRESS_CRC_BYTE) != address[ADDRESS_CRC_BYTE])   // check address CRC is valid
+        {
+            pc.traceOut("CRC is not valid!\r\n");
+            wait(2);
+            return false;
+        }
+
+        if (address[0] != deviceId)
+        {                    
+            // Make sure it is a one-wire thermometer device
+            if (DS18B20_ID == deviceId)
+                pc.traceOut("You need to use a DS1820 or DS18S20 for correct results.\r\n");
+            else if (DS18S20_ID == deviceId)
+                pc.traceOut("You need to use a DS18B20 for correct results.\r\n");
+            else
+              pc.traceOut("Device is not a DS18B20/DS1820/DS18S20 device.\r\n");
+            
+            wait(2);
+            return false;   
+        }
+        else
+        {
+            if (DS18B20_ID == deviceId) pc.traceOut("DS18B20 present and correct.\r\n");
+            if (DS18S20_ID == deviceId) pc.traceOut("DS1820/DS18S20 present and correct.\r\n");            
+        }
+    }
+    
+    return true;
+}
+
+// NOTE ON USING SKIP ROM: ok to use before a Convert command to get all
+// devices on the bus to do simultaneous temperature conversions. BUT can 
+// only use before a Read Scratchpad command if there is only one device on the
+// bus. For purpose of this library it is assumed there is only one device
+// on the bus.
+void OneWireThermometer::resetAndAddress()
+{
+    oneWire.reset();                // reset device 
+    if (useAddress)
+    {
+        oneWire.matchROM(address);  // select which device to talk to
+    }
+    else
+    {
+        oneWire.skipROM();          // broadcast
+    }
+}
+
+bool OneWireThermometer::readAndValidateData(BYTE* data)
+{
+    bool dataOk = true;
+    
+    resetAndAddress();
+    oneWire.writeByte(READSCRATCH);    // read Scratchpad
+
+    pc.traceOut("read = ");
+    for (int i = 0; i < THERMOM_SCRATCHPAD_SIZE; i++) 
+    {               
+        // we need all bytes which includes CRC check byte
+        data[i] = oneWire.readByte();
+        pc.traceOut("%x ", (int)data[i]);
+    }
+    pc.traceOut("\r\n");
+
+    // Check CRC is valid if you want to
+    if (useCRC && !(OneWireCRC::crc8(data, THERMOM_CRC_BYTE) == data[THERMOM_CRC_BYTE]))  
+    {  
+        // CRC failed
+        pc.traceOut("CRC FAILED... \r\n");
+        dataOk = false;
+    }
+    
+    return dataOk;
+}
+
+float OneWireThermometer::readTemperature()
+{
+    BYTE data[THERMOM_SCRATCHPAD_SIZE];
+    float realTemp = -999;
+
+    resetAndAddress();
+    oneWire.writeByte(CONVERT);     // issue Convert command
+    
+    if (useParasiticPower)
+    {
+        // wait while converting - Tconv (according to resolution of reading)
+        wait_ms(CONVERSION_TIME[resolution]);
+    }
+    else
+    {
+        // TODO
+        // after the Convert command, the device should respond by transmitting 0
+        // while the temperature conversion is in progress and 1 when the conversion is done
+        // - as were are not checking this (TODO), we use Tconv, as we would do for
+        // parasitic power 
+        wait_ms(CONVERSION_TIME[resolution]);
+    }
+
+    if (readAndValidateData(data))    // issue Read Scratchpad commmand and get data
+    {
+        realTemp = calculateTemperature(data);
+    }
+    
+    return realTemp; 
+}
\ No newline at end of file
diff -r 000000000000 -r a47e8ec71a4e OneWireThermometer.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OneWireThermometer.h	Wed Sep 06 05:35:15 2017 +0000
@@ -0,0 +1,57 @@
+/*
+* OneWireThermometer. Base class for Maxim One-Wire Thermometers. 
+* Uses the OneWireCRC library.
+*
+* Copyright (C) <2010> Petras Saduikis <petras@petras.co.uk>
+*
+* This file is part of OneWireThermometer.
+*
+* OneWireThermometer 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.
+* 
+* OneWireThermometer 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 OneWireThermometer.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef SNATCH59_ONEWIRETHERMOMETER_H
+#define SNATCH59_ONEWIRETHERMOMETER_H
+
+#include <mbed.h>
+#include "OneWireCRC.h"
+#include "OneWireDefs.h"
+
+typedef unsigned char BYTE;    // something a byte wide
+
+class OneWireThermometer
+{
+public:
+    OneWireThermometer(bool crcOn, bool useAddr, bool parasitic, PinName pin, int device_id);
+    
+    bool initialize();
+    float readTemperature();
+    virtual void setResolution(eResolution resln) = 0; 
+
+protected:
+    const bool useParasiticPower;
+    const bool useCRC;
+    const bool useAddress;
+    const int deviceId;
+    
+    eResolution resolution; 
+    BYTE address[8];
+    
+    OneWireCRC oneWire;
+    
+    void resetAndAddress();
+    bool readAndValidateData(BYTE* data);
+    virtual float calculateTemperature(BYTE* data) = 0;    // device specific
+};
+
+#endif
\ No newline at end of file