Najemy, Daniel wrote:
>
> anyone out there tried programming a PIC16C6XX in-circuit?
> I'm wondering if Microchip offers any tools/accessories to do so.
> I'd like to know if they recommend/offer any standard
> type headers for the pcb - possibly w/ a standard cable.
> My guess is that the other end of this cable would connect to a pc.
> I doubt it.

Lattice Logic sell a widget that plugs into an LPT port,
and a 10-way cable goes to an IDC cable-mount socket,
to mate with a 10-way header on your board with their
ispLogic chips on.

You might look up the pinout and make your pinout
compatible with that.

Be aware that the programming has to happen when the entire
board is powered up. Thus you must design it so that all the
other stuff does not misbehave while the PIC is being
programmed.

When I was designing industrial I/O, I had a fail-safe signal
driven by a watchdog chip. If the watchdog tripped, or
during reset, this signal ensured the hardware 'failed' in
a safe state: outputs := inactive state, LEDs off, etc.
until the CPU was ready for orderly start up.

You could do something similar with in-site programmed
projects. It is a very useful signal.

I don't use programmable logic here, but expect to be
asked for i.s.p. features to cope with PICs and Hitachi
Flash micros soon. With this in mind I hope to make a
widget with a centronics connector one end and headers
for various standards at the other.

Try seeing if the JTAG standard has any standard
connector pinout. Might be worth adopting or making
your own header compatible.

Finally, consider putting a 5V pin on TTL serial I/O
connectors. This lets you power things like external
LEDs and MAX202 TTL-to-RS232 buffers, without
the hassles of extra power supplies. It might also
drive a DC to DC convertor to generate VPP.
I was looking at the 1W 5V->15V ones from Newport
Magnetics to generate the VPP for a Hitachi micro.
Annoyingly, the Hitachi data book does not mention
IPP. I _presume_ this is no more than the maximum ICC
or 60mA, in which case the 1W converter should do it.