File content as of revision 2:193926923cb0:
/*
* 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) <2011> Version 1.2 Wim De Roeve
* <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
Version 2.0: Modifications by Paul Stoffregen, January 2010:
http://www.pjrc.com/teensy/td_libs_OneWire.html
Search fix from Robin James
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
Use direct optimized I/O in all cases
Disable interrupts during timing critical sections
(this solves many random communication errors)
Disable interrupts during read-modify-write I/O
Reduce RAM consumption by eliminating unnecessary
variables and trimming many to 8 bits
Optimize both crc8 - table version moved to flash
Modified to work with larger numbers of devices - avoids loop.
Tested in Arduino 11 alpha with 12 sensors.
26 Sept 2008 -- Robin James
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
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"
// ROM commands
#define OVERDRIVE_SKIP 0x3C
#define MATCH_ROM 0x55
#define SKIP_ROM 0xCC
// 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;
}*/
// reset the search state
LastDiscrepancy = 0;
LastDeviceFlag = 0;
LastFamilyDiscrepancy = 0;
for(int i = 7; ; i--)
{
ROM_NO[i] = 0;
if ( i == 0) break;
}
}
// Changed in version 1.1
//
// 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.
//
// --- Replaced by the one from the Dallas Semiconductor web site ---
//--------------------------------------------------------------------------
// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
// search state.
// Return TRUE : device found, ROM number in ROM_NO buffer
// FALSE : device not found, end of search
//
uint8_t OneWireCRC::search(uint8_t *newAddr)
{
uint8_t id_bit_number;
uint8_t last_zero, rom_byte_number, search_result;
uint8_t id_bit, cmp_id_bit;
unsigned char rom_byte_mask, search_direction;
// initialize for search
id_bit_number = 1;
last_zero = 0;
rom_byte_number = 0;
rom_byte_mask = 1;
search_result = 0;
// if the last call was not the last one
if (!LastDeviceFlag)
{
// 1-Wire reset
if (!reset())
{
// reset the search
LastDiscrepancy = 0;
LastDeviceFlag = 0;
LastFamilyDiscrepancy = 0;
return 0;
}
// issue the search command
writeByte(0xF0);
// loop to do the search
do
{
// read a bit and its complement
id_bit = readBit();
cmp_id_bit = readBit();
// check for no devices on 1-wire
if ((id_bit == 1) && (cmp_id_bit == 1))
break;
else
{
// all devices coupled have 0 or 1
if (id_bit != cmp_id_bit)
search_direction = id_bit; // bit write value for search
else
{
// if this discrepancy if before the Last Discrepancy
// on a previous next then pick the same as last time
if (id_bit_number < LastDiscrepancy)
search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
else
// if equal to last pick 1, if not then pick 0
search_direction = (id_bit_number == LastDiscrepancy);
// if 0 was picked then record its position in LastZero
if (search_direction == 0)
{
last_zero = id_bit_number;
// check for Last discrepancy in family
if (last_zero < 9)
LastFamilyDiscrepancy = last_zero;
}
}
// set or clear the bit in the ROM byte rom_byte_number
// with mask rom_byte_mask
if (search_direction == 1)
ROM_NO[rom_byte_number] |= rom_byte_mask;
else
ROM_NO[rom_byte_number] &= ~rom_byte_mask;
// serial number search direction write bit
writeBit(search_direction);
// increment the byte counter id_bit_number
// and shift the mask rom_byte_mask
id_bit_number++;
rom_byte_mask <<= 1;
// if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
if (rom_byte_mask == 0)
{
rom_byte_number++;
rom_byte_mask = 1;
}
}
}
while(rom_byte_number < 8); // loop until through all ROM bytes 0-7
// if the search was successful then
if (!(id_bit_number < 65))
{
// search successful so set LastDiscrepancy,LastDeviceFlag,search_result
LastDiscrepancy = last_zero;
// check for last device
if (LastDiscrepancy == 0)
LastDeviceFlag = 1;
search_result = 1;
}
}
// if no device found then reset counters so next 'search' will be like a first
if (!search_result || !ROM_NO[0])
{
LastDiscrepancy = 0;
LastDeviceFlag = 0;
LastFamilyDiscrepancy = 0;
search_result = 0;
}
else
for (int i = 0; i < 8; i++) newAddr[i] = ROM_NO[i];
return search_result;
}
// 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;
}
Wim De Roeve