Public for testMax31820
Fork of OneWire by
OneWire.cpp
- Committer:
- hudakz
- Date:
- 2015-06-07
- Revision:
- 1:ca126d554161
- Parent:
- 0:acf75feb0947
- Child:
- 3:441f7a221b92
File content as of revision 1:ca126d554161:
/* Copyright (c) 2007, Jim Studt (original old version - many contributors since) The latest version of this library may be found at: http://www.pjrc.com/teensy/td_libs_OneWire.html OneWire has been maintained by Paul Stoffregen (paul@pjrc.com) since January 2010. At the time, it was in need of many bug fixes, but had been abandoned the original author (Jim Studt). None of the known contributors were interested in maintaining OneWire. Paul typically works on OneWire every 6 to 12 months. Patches usually wait that long. If anyone is interested in more actively maintaining OneWire, please contact Paul. Version 2.2: Teensy 3.0 compatibility, Paul Stoffregen, paul@pjrc.com Arduino Due compatibility, http://arduino.cc/forum/index.php?topic=141030 Fix DS18B20 example negative temperature Fix DS18B20 example's low res modes, Ken Butcher Improve reset timing, Mark Tillotson Add const qualifiers, Bertrik Sikken Add initial value input to crc16, Bertrik Sikken Add target_search() function, Scott Roberts Version 2.1: Arduino 1.0 compatibility, Paul Stoffregen Improve temperature example, Paul Stoffregen DS250x_PROM example, Guillermo Lovato PIC32 (chipKit) compatibility, Jason Dangel, dangel.jason AT gmail.com Improvements from Glenn Trewitt: - crc16() now works - check_crc16() does all of calculation/checking work. - Added read_bytes() and write_bytes(), to reduce tedious loops. - Added ds2408 example. Delete very old, out-of-date readme file (info is here) Version 2.0: Modifications by Paul Stoffregen, January 2010: http://www.pjrc.com/teensy/td_libs_OneWire.html Search fix from Robin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 Jim Studt's original library was modified by Josh Larios. Tom Pollard, pollard@alum.mit.edu, contributed around May 20, 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 "OneWire.h" OneWire::OneWire(PinName pin): wire(pin) { #if ONEWIRE_SEARCH reset_search(); #endif } // Perform the onewire reset function. We will wait up to 250uS for // the bus to come high, if it doesn't then it is broken or shorted // and we return a 0; // // Returns 1 if a device asserted a presence pulse, 0 otherwise. // uint8_t OneWire::reset(void) { uint8_t r; uint8_t retries = 125; wire.input(); // wait until the wire is high... just in case do { if (--retries == 0) { return 0; } wait_us(2); } while (wire.read() != 1); wire.output(); wire = 0; wait_us(480); wire.input(); wait_us(70); r = !wire.read(); wait_us(410); return r; } // // Write a bit. Port and bit is used to cut lookup time and provide // more certain timing. // void OneWire::write_bit(uint8_t v) { wire.output(); if (v & 1) { wire = 0; // drive output low wait_us(10); wire = 1; // drive output high wait_us(55); } else { wire = 0; // drive output low wait_us(65); wire = 1; // drive output high wait_us(5); } } // // Read a bit. Port and bit is used to cut lookup time and provide // more certain timing. // uint8_t OneWire::read_bit(void) { uint8_t r; wire.output(); wire = 0; wait_us(2); wire.input(); wait_us(7); r = wire.read(); wait_us(54); return r; } // // 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 OneWire::write(uint8_t v, uint8_t power /* = 0 */) { uint8_t bitMask; for (bitMask = 0x01; bitMask; bitMask <<= 1) { OneWire::write_bit( (bitMask & v)?1:0); } if ( !power) { wire.input(); } } void OneWire::write_bytes(const uint8_t *buf, uint16_t count, bool power /* = 0 */) { for (uint16_t i = 0 ; i < count ; i++) write(buf[i]); if (!power) { wire.input(); } } // // Read a byte // uint8_t OneWire::read() { uint8_t bitMask; uint8_t r = 0; for (bitMask = 0x01; bitMask; bitMask <<= 1) { if ( OneWire::read_bit()) r |= bitMask; } return r; } void OneWire::read_bytes(uint8_t *buf, uint16_t count) { for (uint16_t i = 0 ; i < count ; i++) buf[i] = read(); } // // Do a ROM select // void OneWire::select(const uint8_t rom[8]) { uint8_t i; write(0x55); // Choose ROM for (i = 0; i < 8; i++) write(rom[i]); } // // Do a ROM skip // void OneWire::skip() { write(0xCC); // Skip ROM } void OneWire::depower() { wire.input(); } #if ONEWIRE_SEARCH // // 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 OneWire::reset_search() { // reset the search state LastDiscrepancy = 0; LastDeviceFlag = false; LastFamilyDiscrepancy = 0; for(int i = 7; ; i--) { ROM_NO[i] = 0; if ( i == 0) break; } } // Setup the search to find the device type 'family_code' on the next call // to search(*newAddr) if it is present. // void OneWire::target_search(uint8_t family_code) { // set the search state to find SearchFamily type devices ROM_NO[0] = family_code; for (uint8_t i = 1; i < 8; i++) ROM_NO[i] = 0; LastDiscrepancy = 64; LastFamilyDiscrepancy = 0; LastDeviceFlag = false; } // // 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 OneWire::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 = false; LastFamilyDiscrepancy = 0; return false; } // issue the search command write(0xF0); // loop to do the search do { // read a bit and its complement id_bit = read_bit(); cmp_id_bit = read_bit(); // 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 write_bit(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 = true; search_result = true; } } // if no device found then reset counters so next 'search' will be like a first if (!search_result || !ROM_NO[0]) { LastDiscrepancy = 0; LastDeviceFlag = false; LastFamilyDiscrepancy = 0; search_result = false; } for (int i = 0; i < 8; i++) newAddr[i] = ROM_NO[i]; return search_result; } #endif #if ONEWIRE_CRC // The 1-Wire CRC scheme is described in Maxim Application Note 27: // "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products" // Compute a Dallas Semiconductor 8 bit CRC directly. // uint8_t OneWire::crc8(const uint8_t *addr, uint8_t len) { uint8_t crc = 0; while (len--) { uint8_t inbyte = *addr++; for (uint8_t i = 8; i; i--) { uint8_t mix = (crc ^ inbyte) & 0x01; crc >>= 1; if (mix) crc ^= 0x8C; inbyte >>= 1; } } return crc; } #endif