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OneWireHub

The OneWireHub is an Arduino compatible (and many more platforms) library to emulate OneWire-Slaves with support for various devices. The motivation is to offer a shared code base for all OneWire-Slaves. With a small overhead one µC can emulate up to 32 ICs simultaneously. The main goal is to use modern sensors (mainly I2C or SPI interface) and transfer their measurements into one or more emulated ds2438 which have 4x16bit registers for values. This feature removes the limitations of modern house-automation-systems. Add humidity, light and other sensors easy to your environment.

Supported Slaves (bold ones are feature-complete):

  • DS1822 Digital Thermometer, 12bit (use DS18B20 with family code set to 0x22)
  • DS18B20 Digital Thermometer, 12bit
  • DS18S20 Digital Thermometer, 12bit (use DS18B20 with family code set to 0x10)
  • DS1990 iButton (use DS2401 with same family code 0x01)
  • DS2401 Serial Number
  • DS2405 Single address switch
  • DS2408 8-Channel Addressable Switch, GPIO Port-expander
  • DS2411 Serial Number (use DS2401 with same family code 0x01)
  • DS2413 Dual channel addressable switch with input-sensing
  • DS2423 4kb 1-Wire RAM with Counter
  • DS2433 4Kb 1-Wire EEPROM
  • DS2438 Smart Battery Monitor, measures temperature, 2x voltage and current, 10bit
  • DS2450 4 channel A/D
  • DS2890 Single channel digital potentiometer - extended to 1-4 CH

Features:

  • supports up to 32 slaves (8 is standard setting), adjust HUB_SLAVE_LIMIT in OneWireHub.h to safe RAM & program space
  • hot-plug slaves as needed
  • cleaner, faster code with c++11 features (requires arduino sw 1.6.x or higher)
    • i.e. use of constexpr instead of #define for better compiler-messages
  • hardware-dependencies are combined in "platform.h", synced with onewire-lib
    • extra supported: arduino zero, teensy, sam3x, pic32, ATtiny, esp8266, nrf51822 (...)
    • for portability and tests the hub can even be compiled on a PC with the supplied mock-up functions
    • at the moment the lib relies sole on the micros()-fn for timing, no direct access to interrupt or timers
  • Serial debug output can be enabled in OneWireHub.h: set USE_SERIAL_DEBUG to 1
  • good documentation, numerous examples, easy interface for hub and sensors

Recent development (latest at the top):

  • hub is more robust to odd master-behaviour (lazy timings and subsequent resets)
  • prepare new timing-method which will replace the old one in the next couple of weeks (a 6µs millis() call at 8MHz is not suitable for OW)
  • cleanup send / receive / waitForTimeslot to react faster to bus (better for µC with less than 16 MHz)
  • support for skipROM-cmd if only one slave is present (thanks to Giermann)
  • speed up atmel-crc-functions
  • tested with DS9490R: ds28b20, ds2401, ds2405, ds2413, more will follow
  • rework of error system, switch to enum, slaves can raise errors now & and Serial interferes less with OW-timings
  • rework of the whole timings, if needed you can configure overdrive speed (arduino uno would probably be to slow)
  • bug fix: non conformal behaviour as a onewire-slave (hopefully)
  • raise the maximal slave limit from 8 to 32, code adapts via variable dataTypes
  • open up for a lot more platforms with "platform.h" (taken from onewire-lib)
  • per-bit-CRC16 with sendAndCRC16() and sendAndCRC16() for load-balancing, 900ns/bit instead of 7µs/byte on Atmega328@16MHz
  • add examples for onewire-master, for testing the bus
  • rework of checkReset(), showPresence(), send(), recv() - Hub is much more reliable now and it saves ~120 byte program-space
  • faster CRC16 (ds2450 and ds2408 and ds2423), takes 5-7µs/byte instead of 10µs
  • refactored the interface: hub.poll() replaces hub.waitForRequest()
  • extended ds2890 to up to 4CH (datasheet has it covered), ds2413, ds2413 --> feature-complete
  • implement and test ds2438
  • replace search() algorithm, safes a lot of ram (debug-codeSize-4slaves.ino needs 3986 & 155 byte instead of 3928 & 891 byte) and allows >4 devices

Plans for the future:

  • implementation of ds2450
  • add table of tested and working sensors
  • irq-handled hub on supported ports, split lib into onewire() and onewireIRQ()
  • test each example with real onewire-masters, for now it's tested with the onewire-lib and a loxone-system (ds18b20 passed)
  • DS1963S 0x18 iButton, datasheet under NDA
  • List of all Family-Codes
  • List of Maxim Sensors (at the bottom)

Connecting the HUB with the Network:

Onewire-Schematic

read more

Parasite Power with two wires

Parasite-Power-Schematic

read more

Ancestors of this Lib:

  • original pieces seem to be adopted from OneWireSlave
  • further development was done in OneWireSlave from MarkusLange and OneWire
  • first implementation of the OneWireHub by Shagrat2
  • the current state of code has the concepts in common, but the codebase is a total rewrite