Diff: OneWire.cpp

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0:acf75feb0947

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1:ca126d554161

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+++ b/OneWire.cpp	Sun Mar 15 14:13:55 2015 +0000
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+/*
+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+  Delete very old, out-of-date readme file (info is here)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(9);
+    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