Quote Originally Posted by Darrel Taylor View Post
On many chips, RA4 is Open-Collector and won't drive the pin high on it's own.

I'm assuming you're still using an 18F4550.

The datasheet doesn't specify, but in ISIS with an 18F4550, the LCD won't initialize without a pull-up.

It could just be a simulator thing.

Try it.
Stick a pull-up in there.
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Tried a 10K pull-iup on RA4 and still no characters appearing on LCD. Going to hook up oscilloscope next to the various LCD interfaces to see if I can figure out what is going on.

I don't know what ISIS is or what you mean by it could be just a simulator thing. Is ISIS a simulator?

For your info I asked Microchip tech support about whether RA4 on 18F2550/4550 is open-collector or not and whether there should be any problem of it driving RA4 high with an LCD interface and here is their response:
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Hi,
Thank you for contacting Microchip Technical Support.
RA4 can drive the pin High, please configure all the Port pin of PortA to digital by setting the bit in PCFG0-PCFG3 in ADCON1 Register.
For further assistance, do write to us with the following details.
1) Please attach your code along with MPLAB IDE workspace.(MCP and MCW files)
2) C18 -Version?
3) MPLAB version?
4) Screen shot of the disassembly listing in the view tab.
Awaiting for your reply
Thanks & Regards,
Microchip Technical Support