CM15A

[nobody@xxxxxxxxxxxx (Dave Houston)]

I have continued to kick around possible designs for a CM15A daughterboard
to replace the MCU that X-10 is using.

I think I finally have a workable design and am about to order a handful of
prototype boards for testing. It will be a month or more before I have the
prototypes and can start testing and is likely to be several weeks after
that before it will be available.

The daughterboard is 0.830" x 1.200" and plugs into the socket in place of
the Cypress MCU. If your MCU is not socketed I recommend that you desolder
it and install a socket. That way you can always go back to the original
MCU.

Two versions are planned. One will have a serial interface (RS-232 but
0-5V). The other will use USB but, on the PC end, use virtual com port
drivers which are available for W98SE, W2K & XP, OS X, and Linux. PC
software can be the same for both the RS232 and USB versions as the VCP acts
like a standard RS232 port. The RS232 version requires an adapter cable (USB
to CM15A, DB-9F to PC).

The board has a PIC16F88 with a small bootloader so its firmware can be
changed over the serial or USB link. The PIC16F88 will handle communications
with the PC (using its hardware USART), the EEPROM (using the PIC's SCL &
SDA pins), PLC, and RF out.

There is also a PIC12F683 which handles the RF receiver and manages an RS485
network. The RS485 network can include additional RF receiver modules which
will allow inputs from devices that use other frequencies (e.g. 418MHz used
by many touchscreen remotes). The firmware will handle standard X-10 RF,
security X-10 RF, Digimax 210 thermostat RF, and Ninja/Robocam RF.

The CM15A EEPROM is 8K which is 8 times the size used in the CM11A. I plan
to include support for an optional 32K EEPROM (will require soldering to
replace the existing EEPROM). I recommend adding an external eggbeater
antenna (and preamp, if necessary). Replacing the antenna requires soldering
two connections.

The firmware will include many of the features that I built into the
BX24-AHT. I'll provide free Windows interface software (similar to that for
the BX24-AHT) but will leave it to others to write something for other
operating systems.

If others want to develop firmware for it, the boards can be supplied
without the PIC16F88 (PDIP). The PIC12F683 can be supplied preprogrammed or
developers can program it themselves via ICSP.

I think it will cost $35-40. Developer boards will cost about half that (w/o
PIC16F88). Since it does not disturb any of the RF hardware, there are no
FCC issues to deal with.

Schedules assume the prototype boards work and my health holds up for a few
more months.