OneWireCRC.h

00001 /*
00002 * OneWireCRC. This is a port to mbed of Jim Studt's Adruino One Wire
00003 * library. Please see additional copyrights below this one, including
00004 * references to other copyrights.
00005 *
00006 * Copyright (C) <2009> Petras Saduikis <petras@petras.co.uk>
00007 *
00008 * This file is part of OneWireCRC.
00009 *
00010 * OneWireCRC is free software: you can redistribute it and/or modify
00011 * it under the terms of the GNU General Public License as published by
00012 * the Free Software Foundation, either version 3 of the License, or
00013 * (at your option) any later version.
00014 * 
00015 * OneWireCRC is distributed in the hope that it will be useful,
00016 * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00018 * GNU General Public License for more details.
00019 *
00020 * You should have received a copy of the GNU General Public License
00021 * along with OneWireCRC.  If not, see <http://www.gnu.org/licenses/>.
00022 */
00023 /*
00024 Copyright (c) 2007, Jim Studt
00025 
00026 Updated to work with arduino-0008 and to include skip() as of
00027 2007/07/06. --RJL20
00028 
00029 Modified to calculate the 8-bit CRC directly, avoiding the need for
00030 the 256-byte lookup table to be loaded in RAM.  Tested in arduino-0010
00031 -- Tom Pollard, Jan 23, 2008
00032 
00033 Permission is hereby granted, free of charge, to any person obtaining
00034 a copy of this software and associated documentation files (the
00035 "Software"), to deal in the Software without restriction, including
00036 without limitation the rights to use, copy, modify, merge, publish,
00037 distribute, sublicense, and/or sell copies of the Software, and to
00038 permit persons to whom the Software is furnished to do so, subject to
00039 the following conditions:
00040 
00041 The above copyright notice and this permission notice shall be
00042 included in all copies or substantial portions of the Software.
00043 
00044 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00045 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00046 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00047 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
00048 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
00049 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
00050 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00051 
00052 Much of the code was inspired by Derek Yerger's code, though I don't
00053 think much of that remains.  In any event that was..
00054     (copyleft) 2006 by Derek Yerger - Free to distribute freely.
00055 
00056 The CRC code was excerpted and inspired by the Dallas Semiconductor 
00057 sample code bearing this copyright.
00058 */
00059 //---------------------------------------------------------------------------
00060 // Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
00061 //
00062 // Permission is hereby granted, free of charge, to any person obtaining a
00063 // copy of this software and associated documentation files (the "Software"),
00064 // to deal in the Software without restriction, including without limitation
00065 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
00066 // and/or sell copies of the Software, and to permit persons to whom the
00067 // Software is furnished to do so, subject to the following conditions:
00068 //
00069 // The above copyright notice and this permission notice shall be included
00070 // in all copies or substantial portions of the Software.
00071 //
00072 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
00073 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00074 // MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
00075 // IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
00076 // OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
00077 // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
00078 // OTHER DEALINGS IN THE SOFTWARE.
00079 //
00080 // Except as contained in this notice, the name of Dallas Semiconductor
00081 // shall not be used except as stated in the Dallas Semiconductor
00082 // Branding Policy.
00083 //--------------------------------------------------------------------------
00084 
00085 #ifndef SNATCH59_ONEWIRECRC_H
00086 #define SNATCH59_ONEWIRECRC_H
00087 
00088 #include <mbed.h>
00089 
00090 // Select the table-lookup method of computing the 8-bit CRC by setting this to 1
00091 #ifndef ONEWIRE_CRC8_TABLE
00092 #define ONEWIRE_CRC8_TABLE 1
00093 #endif
00094 
00095 typedef unsigned char BYTE;    // used to be uint8_t : something a byte wide, whatever ....
00096 
00097 enum eSpeed {OVERDRIVE, STANDARD};
00098 
00099 class OneWireCRC
00100 {
00101 public:
00102     OneWireCRC(PinName oneWire, eSpeed);
00103     
00104     // reset, read, write functions
00105     int reset();
00106     void writeByte(int data);
00107     int readByte();
00108     int touchByte(int data);
00109     void block(BYTE* data, int data_len);
00110     int overdriveSkip(BYTE* data, int data_len);
00111     
00112     // address functions
00113     void matchROM(BYTE rom[8]);
00114     void skipROM();
00115 
00116     // address search functions
00117     void resetSearch();
00118     BYTE search(BYTE* newAddr);
00119 
00120     // CRC check functions
00121     static BYTE crc8(BYTE* addr, BYTE len);
00122     static unsigned short crc16(unsigned short* data, unsigned short len);
00123 
00124 private:
00125     const int* timing;
00126     
00127     BYTE address[8];
00128     int searchJunction;        // so we can set to it -1 somewhere
00129     bool searchExhausted;
00130     
00131     DigitalInOut oneWirePort;
00132     
00133     // read/write bit functions
00134     void writeBit(int bit);
00135     int readBit();
00136 };
00137 
00138 #endif