Honeywell Smartfit research and the start of a generic interface (wish me luck!)

[James Derrick <james-ukha@xxxxxxx>]

Hi All,

After trying a few different ways of integrating domestic heating with
home brew home automation, I have splashed out in a Honeywell Smartfit
system in the hope that experimentation will lead to a generic
interface to the Accessory Port.

So far, I have put on the web details of what Smartfit is, my existing
heating system, and the progress so far on making my own interface:

http://www.amarok.demon.co.uk/dl/hvac/index.html
(click on the diagrams to get a full-size view)


Don't get too excited yet- my PIC-based test rig can reliably read the
data bits sent across the Smartfit bus, but the packet format is still
a mystery to me. With luck, this will only be a matter of time and a
generic PIC interface will take shape.

The test rig is based on Maxim PIC chips (10MHz 16F84 single chip
microcontroller) programmed using Crownhill's PROTON+ BASIC compiler
so as to concentrate on the interface rather than assembly language.

For what it is worth, circuits and BASIC files are available so please
feel free to have a go- the more the merrier! If you want HEX files to
program PICs, drop me an email but it's early days yet.

My goal is to build an interface that is capable of communicating with
the Smartfit unit to both read status and set parameters. The
client-side interface is likely to be a simple serial such as ASCII
RS232 or RS485 usable with MisterHouse on a PC. As I'm using PICs,
other interfaces will be possible.

Wish me luck!


James
---
James Derrick
james-ukha@xxxxxxx, Cramlington, England
Beyond the Horizon of the place we lived when we were young,
In a World of Magnets and Miracles. Pink Floyd.