Diff: OneWireCRC.cpp

Revision:

0:01a6a40578c9

diff -r 000000000000 -r 01a6a40578c9 OneWireCRC.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OneWireCRC.cpp	Sun Jan 03 11:57:31 2010 +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;
+}
+