I use
http://eagle.cc.ukans.edu/~mturvey/firecracker.html
as a starting off point for the firecracker interface.  It is not similar to the
CM11A interface:

Consists of a PIC12c5xx, a transister, 5 or so resisters, 3 caps, two 1n4148
diodes, and a 5v1 zener.  Three wires go to the serial port, RTS, DTR and GND.
Signalling is accomplished by bringing both RTS and DTR high, and switching
either one off according to whether one wants to send a 1 or a 0 to the pic.
Quite a cool idea, IMHO.

I've 'decoded' the 16 data bits mentioned in the protocol specification:
http://www.x10.com/manuals/cm17a_proto.txt
and will be posting it to my web site later today.

-Adam
http://www.ubasics.com/adam/

Adam Bryant wrote:
>
> Tell me more.  Is it the same protocol used to talk to the X10 CM11A
> computer interface module?  Any links to additional information would be
> greatly appreciated.
>
> Thanks,
> Adam
>
> On Wed, 11 Aug 1999 16:23:27 -0400 Adam Davis <adavis@BALADYNE.COM>
> writes:
> > Yes, it is quite a spiffy little device.  There are details on the
> > 'net about
> > the protocol for communicating with the pic and the transmission
> > protocol, as
> > well as the frequency (I think 300MHz??).
<snip></snip>
> > -Adam