RaspberryPi 1-Wire Expansion

You can’t have failed to notice the buzz around the upcoming RaspberryPi.

Both it’s price £25 for Model B (with ethernet connectivity) and size make it ideally suited to home automation, of particular interest is the expansion header that makes several GPIO connections available.

Included on this header is an i2c connection, making it an ideal candidate as a 1-wire to ethernet convertor for OWFS.

I’ve begun work on two 1-wire breakout boards, both making use of the i2c to 1-wire master chips that are available, providing a single and eight channels using the DS2482-100 and DS2482-800 chip.

Board Features are as follows

  • RJ45 1-wire connection using the 1WRJ45 wiring standard.
  • GPIO Header for connection to RaspberryPi
  • 8 way GPIO Breakout header
  • 2 SPI breakout headers , one for each SPI enable line
  • Screw terminal for 5V power supply connection
  • i2c Level conversion from 3.3v to 5v
  • 3 pin DS18B20 connection (8 way board only)
  • 6 way 1-wire expansion header (8 way board only)

 

Screen shots of initial PCB layout below, PCB’s are 5cm x 5cm in size.

 


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