1-Wire Network Printed Circuit Board

In order to simplify the addition of devices and features to my 1-Wire network and in particular to support my 1-Wire network power injector, I've designed a PCB that can be used to support a wide range of functions. The design (Version 1E) and the possible applications and configurations were captured in a MS Powerpoint presentation.

Design Notes

• The 1-Wire GND cannot be connected to any other earth reference point as this will damage the 1-Wire adapter. This means that although I've connected all of the grounds, the 12V supply must not be earthed as the whole network is basically floating.
• A Schottky diode across 1-Wire DATA and 1-Wire GND provides protection by clamping signal excursions below ground to ~0.4V.
• Pin 6 (normally not connected) is daisy chained through the network to support continuity testing.

Manufacture

Having done an initial design layout using Microsoft Power point, the board design was entered into a proper PCB drawing tool by a work colleague, who also has photoboard production facilities and and an etching tank. He introduced me to some Freeware PCB design software called Eagle  and this is what we are using to capture and produce the design.

This is the version 1.0 of the etched PCB. The holes are yet to be drilled to allow mounting of the components. The first application for this board was for 1-Wire network power injection.

Applications

1-Wire Power

The primary function of this device is to support 1-Wire network power injection and I'm using this board as the first node in my network to achieve this. The board accepts a 12V unregulated input and has a 5V voltage regulator on it to supply the 5V down the network.

Temperature Sensor

The board can also support being a simple temperature sensing node with a DS1920 temperature sensor. This can work in parasitic power mode or a jumper can connect it to +5V from the 1-wire network.

PIR Sensor

To enable a 1-Wire PIR, the board can interface to and fit within a 12V PIR sensor for security and occupancy detection. It delivers the required 12V to power the PIR and uses a DS2405 to detect occupancy.

Door / Window Monitoring

To board can be configured to monitor the status of a door, using a reed swtich and magnet, with a DS2405 to switch status changes.

Change History

Version 1.1 - 15/09/2007

Added a few more spare pads for development and testing of ideas, made a few pads bigger to aid drilling process.

Version 1.0 - 15/09/2007

First manufactured version for drilling and testing. Currently in use as my 1-Wire network power injector.

Version 0.9 - 10/08/2007

Added support for a Schottky diode across 1-Wire DATA and 1-Wire GND.

Version 0.8 - 09/08/2007

First public version exposed for comment and improvements.