At 08:18 AM 1/31/02 EST, you wrote:
>Hi Michael, I think I see your problem RA4 is open drain output.
>One of the EE guys can explain it better than I, but I never
>use it like a normal I/O pin. I am not sure if you can
>just add a pullup resistor or not ?

A pullup resistor should make it work fine in this case- it's just
driving a CMOS (TTL level) input. The only caveat is that the
transition from 0->1 will be a bit slower than if it was a
push-pull output, with a relatively high 10K and 25pF of
load capacitance, it would be in the 250nsec range. Probably not
a problem unless your timing is tight- minimum steup time
is 140 nsec usually, so a NOP or two (depending on the PIC
clock frequency) wouldn't hurt if you are clocking the E line with
the next instruction after setting RS -> 1.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

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