RE: All Lights On/All Units Off and Modifying an MT10

["K. C. Li" <li@xxxxxxx>]

On Sun, 11 Nov 2001, Mark Hetherington wrote:

> It ought to be trivial even without the source code since somewhere
the
> button is sending 0001 and I just want to change it to send 1101. It
might

You obviously are unfamiliar with the X-10 protocol requirements and
perhaps electronics circuits in general. You are talking about changing
the preprogrammed X-10 binary command sequence. The buttons are connected
directly to the CPU input pins to signal which command has been selected
by the user. They don't do the actual sending of X-10 commands.

> require some disassembly to locate the exact sequence that needs
changing
> but this should be quite trivial. Custom chips would prevent this
obviously

You probably would not be able to read off the firmware program on most
standard microcontrollers, let alone a custom one. Practically all
programmable chips (OTP, flash, EEPROM) have security protection built in
to prevent the disclosure of the control programs inside. There are ways
to defeat various protections, depending on how much one is willing to
spend. There are a small number of chips that can be cracked relatively
easily (eg. PIC16F84) but for the majority, the protection is almost
impossible to defeat by the likes of you and I.

Regards,

Kwong Li
li@xxxxxxx
Laser Business Systems Ltd.
http://www.laser.com