Using a new PIC part no. for the first time is always such an adventure.

[afbecker]

I spent 6 hours studying the docs. It didn't take long to get the oscillator right but disabling all the special purpose pins is a real bear.

Anyway, I got the USART working, partly anyway, I can get the PIC to output text to the PC via my serial cable and RS232-9 pin connected to TX pin, but sending characters back to the PIC into the RC pin, is really not working. I have set BRGH high (1) and SPBRG for 9600 (25) for the 4Mhz Fosc. Enabled receive and set all the other bits I can determine to be necessary. Still no go.

Maybe the internal RC clock is not precise enough. I am going to retrofit an external oscillator ext and see if that works, otherwise I've hiot another wall.

Anyone out there used this animal in USART implementation?

[mister_e]

I know it's a long debate and some have success, some not, but i never suggest to use internal osc for reliable serial comm. BUT you can reduce the baudrate, say 2400 baud, and do some tests.

Use PICMultiCalc to get the USART settings for you.
http://www.mister-e.org/pages/utilitiespag.html

Yours seems to be the good one... just post your code here and maybe we could suggest you few things.

[afbecker]

Pretty cool calculator. Looks like you have a pretty good handle on DataComm.

I'm going to retrofit the external osc. tonight and see what happens. I only have two osc. right now that run at 4Mhz. That has always been fast enough on my 16F628A's to get 9600. In my real time application though, 2400 might be enough.

I refined the code last night and will work on it again tonight, so I could attach it as a .txt file tomorrow.

[afbecker]

I found and 8Mhz osc. laying around and put it into the circuit. With the specs. from the baud calculator inserted into the code the code ran first time out giving me accurate I/O from the PC. Now I'm just one pin short of getting 32 outputs. I'll probably be forced to use the input only MCLR as a DebugIn and another one for DebugOut instead of the hardware serial. That would free up C6 & C7 for outputs.

Thanks for the pointers.

[mister_e]

well, there's always pros and con for using external OSC, if you have many push buttons, you may use the ADC and read from it. a r2r network and ADC can work with at very least 16 push buttons. many many stuff can be multiplexed as well.

You could also waste your time and try to tweak the internal osc using OSCTUNE... as i said... a REAL waste of time knowing the cons of internal RC osc for reliable timing needs.