• emulates a bus master in a generic way, the lib is handling most of the timing-constrains and the hardware-access
• clean, small, fast code with c++11 features (requires arduino sw 1.6.x or higher)
• proper naming of variables make it easier to read the code
• hardware-dependencies are combined in "platform.h" (see next section)
  • for portability and tests the lib can be compiled on a PC with the supplied mock-up functions in platform.h
• extended and easy understandable examples
• command to enable or disable parasitic bus powering by the master (was implemented wrong before)
• compiler-switch to use pull-ups of micro controller
• improved documentation in doxygen style
• decided on one code style - Allman braces - was closest to main style in original

• embedded real life test
  • setup: run ds18x20-master, enabled internal pull up (if possible), arduino 1.8.3, Windows 10 and the board-library named in the brackets
  • Arduino Uno (Arduino AVR Boards)
  • Arduino Due (Arduino SAMD Boards (32-bits ARM Cortex-M3)) -> NOTE: internal PU is not strong enough to power bus
  • Arduino MKRZero (Arduino SAMD Boards (32-bits ARM Cortex-M0+)) -> NOTE: internal PU is not strong enough to power bus
  • Teensy 3.2 (teensyduino)
  • Wemos D1 Mini ESP32S (esp32) -> NOTE: internal PU is not strong enough to power bus
  • Wemos Wifi & BT ESP32 (esp32) -> NOTE: internal PU is not strong enough to power bus
  • Wemos D1 R2 (esp8266)
  • nodeMCU 1.0 ESP-12E (esp8266)
• Travis CI (automated Continuous Integration) for different platforms
  • Arduino Uno (Arduino AVR Boards)
  • Arduino Due (Arduino SAMD Boards (32-bits ARM Cortex-M3))
  • Arduino Zero (Arduino SAMD Boards (32-bits ARM Cortex-M0+))
  • Arduino 101 (Intel Curie Boards)
  • Teensy 3.0, 3.1, 3.2, LC, 3.5, 3.6 (teensyduino)
  • generic ESP8266 (esp8266)
  • nodeMCU V2 (esp8266)
  • espduino (esp8266)
  • ESP32 dev module (esp32)
  • RFduino nrf51 (RFduino)
  • ATtiny 84, 88 (attiny??)
  • Digispark tiny (DigistumpArduino)
• manual compile test: process passes
  • setup: run ds18x20-master, arduino 1.8.3, Windows 10 and the board-library named in the brackets
  • Arduino Primo (Arduino nRF52 Boards)
  • Teensy 2.0, 2.0++ (teensyduino)
  • Digilent chipKIT UNO32 pic32
  • RedBear nRF51
• if you successfully tested a new controller don't hesitate to open an issue on github to document it
• if you modified / extended the lib to support new hardware don't hesitate to open a pull request on github

• understanding onewire protocol helps a lot during "how to"
• connect your microcontroller (onewire-master) with the onewire-bus
  • the onewire-bus should be set up as described in separate section below
• the examples are mostly self explanatory
  • the microcontroller acts as a master
  • it will search and select devices on the bus
  • master will read data from devices
  • data is processed and send via uart to the pc
• onewire.h has the following compiler-switches to enable special features
  • USE_CRC8_TABLE: will trade compilation size for speed
  • USE_PULL_UP: activate internal pull up of microcontroller (external bus PU most likely not needed then)

• check if your arduino software up to date (>v1.6.8)
• update this lib to the latest release (v3.0.0)
• check if clock-speed of the µC is set correctly (if possible) - test with simple blink example, 1sec ON should really need 1sec. timing is critical
• begin with a simple example like the ds18x20 (if possible) or the bus_discovery example
• check if your setup is right: see sections below
• is there more than one master on the bus? It won't work!
• has any other master ever worked with the slave device?
• if you can provide a recording via logic-analyzer (logic 8 or similar) there should be chance we can help you
• if you checked all these points feel free to open an issue at Github and describe your troubleshooting process
  • please provide the following basic info: which µC do you use, software versions, what device do you try to work with, what works, what doesn't

• update the interface, NOTE: these changes can be made without breaking old code, just use "deprecated" on old interface
  • simplify bus powering as extra argument for reset and read as well, OR we set it on bus constructor
  • predefine standard onewire commands and use send(), skip() is not needed then
• unit tests
• collect timings in variables
• add pull up support directly to constructor
• overdrive and other features (alarm search)
• add or extend hardware support
  • stm32f4 https://github.com/arduino-org/arduino-core-stm32f4
  • stm32 https://github.com/rogerclarkmelbourne/Arduino_STM32
  • msp430 E https://github.com/energia/Energia
  • msp430 arduino, platformIO speaks of a different framework
• add travis tests, currently not supported
  • NRF52 /* arduino primo */
  • NRF51 /* red bear blend, should be good for all nrf51x chips */
  • pic32 -> problem with toolchain in platformIO
  • teensy 2 -> crc-lib has linker problem in platformIO

Version 3.0

• real life tested with several platforms (atmega, atsamD21, Atsam3x, esp8266, esp32, teensy)
• extend and fix hardware support (specially esp-boards, esp32, ...)
• added travis CI for a big bunch of controllers
• delayMicroseconds() hardware abstraction to allow proper nRF51-use (redbear messed up the delaymicroseconds()-implementation)
  • will be removed as soon redbear fixes its code
• overload write() to replace write_bytes() and read() to replace read_byte()
• update code documentation, doxygen style
• allow to use internal pull-up if micro controller has support for it -> most µC support INPUT_PULLUP in combination with pinMode(), others will get an error message or warning if feature is enabled but not supported / tested
• clean up compiler-switches
• better implementation to allow parasitic power to bus, otherwise master will act as open-drain-only! -> this was totally wrong before as the bus was powered for a short amount of time even if powering is disabled
• extend examples with ds2438 and a bus-discovery feature
• clean up examples, easier to understand, more similar to each other
• put hardware dependant code into platform.h
• better naming of variables and a lot of code cleanup
• simplify pin-access and interrupt-handling
• improve onewire class-interface (it was possible to copy the object, ...)
• reduce size of data types if possible, more const correctness and much more explicit code
• get rid of most ancient c and cpp code and reduce language mix
• decide on one code style - Allman braces - was closest to main style in original
• a lot of how-to documentation for this lib inside this readme

Version 2.3

• Unknown chip fallback mode, Roger Clark
• Teensy-LC compatibility, Paul Stoffregen
• Search bug fix, Love Nystrom

Version 2.2

• Teensy 3.0 compatibility, Paul Stoffregen, [email protected]
• Arduino Due compatibility, http:https://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:https://www.pjrc.com/teensy/td_libs_OneWire.html
• Search fix from Robin James http:https://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

Version before 2.0

• Modified to work with larger numbers of devices - avoids loop. Tested in Arduino 11 alpha with 12 sensors. 26 Sept 2008 -- Robin James
• 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

• the picture does not show the power line (assumes parasitic powering)
• by activating the internal pull up of the microcontroller you most likely do not need external PU

read more

advantages:

• reduce number of wires to the slave device

how to do it:

• you will need to activate power-argument on the send-routines or use power()-function of the master
• for low power devices like the ds2401 it should be possible to just lower the resistance of the pullup-resistor of the bus (~1k)
• most slave devices have the circuit shown in the lower picture already included (consult datasheet)
• note: you should only activate / use this feature if you know what you are doing
• possible safety-precaution: do not directly connect the master-pin to the bus, instead add ~200 Ohm between -> in case of shortage or any other bus failure there will only be ~16mA of current flowing

read more