Re: for Anand Dhuru

["Anand" <ardhuru@xxxxxxxx>]

Thanks for the valuable pointers again, Dave.

I now have a collection of mains front end circuits, and am tring to
decide on one (or a combination with ideas borrowed from some).

I have one query, Dave; correct me if I am wrong.

Assume that only an injector is required (reception not required).

You have X10 data coming out of the PIC. *The transformer generates the
120 KHz carrier*, and PIC data modulates this so one ends up with 120
KHz modulated X10 data coupled by the transformer into the mains.

Am I right so far? or is it that the data coming out of the PIC is
already pre-modulated by the PIC at 120KHz (regardless of whether a
direct or a transformer coupling is used)? I know the latter happens
with the AN236 design.

If my earlier assumption is correct, then in transformerless designs
one would have to also generate the 120 KHz within the PIC (as in
AN236), or externally using an oscillator to modulate the X10 data.

You mentioned you did not get a decent transfer using the circuit in
app. note AN236. This could perhaps be on account of the front end
using 5 volts, as against the 18 - 30 volts hat X10 uses?

I use a 16F877 when I connect using a PL513; I prefer to use a
bootloader as far as possible. But when I'm experimenting with my own
interface, I prefer to use a 16F628, as I wouldnt like to share any
line with the PC with either a bootloader or an ICSP cable.

Regards,

Anand