Sat Aug 9 16:33:00 BST 2008
I started building a 18F1320 prototype which has this male connector
as its programming connector. Next is to find out where to connect
the outputs and inputs of the female connector.
A single input is necessary for the bit-banged serial receive.
Probably another one, or this one shared, for some client->host signal
when using the ICD2 port alone for monitor operation.
Either interrupt on change, or the INT0-INT2 pins can be used.
TXD bit banged serial transmit
/MCLR O target reset
VDD O optional target power
PGD I/O data
PGC O clock
PGM O low voltage programming
Later this could be extended with a charge pump for generating the
* RA4 = open drain
* general purpose ports (not using analog): RA0-3
* more (not using oscillator): RA6-7
Probably best to use RA0-3 for the 4 outputs-only ports /MCLR VDD PGC
PGM. Let's use INT0/RB0 for PGD I/O.
So, what should I do first?
* Get the monitor to work with the ICD2 connector only.
* Build a programmer.
The programmer seems rather trivial. The most difficult problem to
solve now is to get a bidirectional communication going over the ICD2
Some things to think about. The only benefit of this device is to be
able to use both from-scratch programming + staapl console. It is
beneficial for smaller targets when there is actually a charge pump
available. Maybe it is better to just modify the firmware of an
already existing programmer? The ICD2 would be a good target.