[vdr] Re: Ready: IR Controller with remote power on

[Thomas Breuer <tb@tb-electronic.de>]

Am 05.08.2002 23:34 schrieb Christian Vogt:

> I have a question about the reset/pwr header: Are you really shure that all
> mainboards out there use the reset & power switches to make a short circuit
> to GND?

http://www.formfactors.org/developer/specs/microatx/matxelec.pdf

page 12: FPBUT_IN, page 13: FP_RST#

You're right, it's not clearly specified (at least not for the pwr
switch). However, like suggested in table 4 on page 12, all ATX MBs I've
ever seen had a GND pin next to the reset and pwr pins. And using active
low signals is very common.

> Otherwise I'd prefer a small reed relay. (this also would simplify
> interfacing to the mainboard, because you don't have to check wether of the
> two pins of the reset/power header is GND...)

Then you'd be on the safe side, although I try to avoid mechanical
relays whenever I can ...

[Improvements]
> Hmm, hopefully this does _not_ mean you won't work on this project any more.

Well, my prototype works, and I'm not going to change this. But of
course I would like to build an improved version and/or other add-ons.
The problem is that there is never enough time ...

> Maybe I can assist in improving the hardware and PIC code ?

You've already started, haven't you? This was one reason for publishing
this little project, so go ahead!

> One more thing:
> I've just taken a look at the datasheed / programming spec of the 16F628. We
> may use the low voltage program/verify mode together with some connections
> between the RS232 control lines and RB4, RB6, RB7 and /MCLR to enable a
> firmware download via RS232. We would need a special program on the PC to
> perform the download sequence and we can't verify at different supply
> voltages, but we would be able to exchange the firmware without opening the
> PC-case, and - maybe the main advantage - we won't need a preprogrammed PIC
> or an additional programmer then. What do you think?

Sounds very interesting. Not only limited to this project, but to all
PIC based circuits. You could even reserve a key on the remote control
to tell the PIC to update it's own firmware ;-)
Could you write the host application? I am actually specialized in
hardware design, and my programming knowledge is currently limited to
writing some assembler code ...

Thomas