Port C on PIC18F2420 not working

[barryw]

I have a problem in that the port C on a PIC18F2420 can't be controled! all works in simulation however once the program is compiled port C seems to be switched to all output's set to low, port A & B are OK (in and outputs on port A OK, LCD connected to port B is also OK) I have tried to set port C with
a "C" function (TRISC = 0xfc;) but still no control. any Idea's?

[Benj]

Hello Barry,

Please can you post up your program or a program that exibits this problem and I will take a look for you. From looking at the device datasheet there doesn't seem to be anything out of the ordinary with PortC on these devices.

[barryw]

port c test.fcf

(40.71 KiB) Downloaded 226 times

Hi Ben,
I hope the attachment is ok as I an not used to this froum. As I said all works well in simlation but not in hardware. I had tried to use port c for the display
and noticed that leds connected to bort b (bits 2 & 3 ) were misbehaving too wilst in simulation.
Regards

Barry w

[Benj]

Hello Barry,

I have just had a look at your program and it seems to be fine. I cant find any reason that PortC should not be working correctly for you.

I would do the following C code in a blank program to see if you can make the lower nibble of PortC do anything.

trisc = 0x00;
portc = 0x01;
delay_s(2);
portc = 0x02;
delay_s(2);
portc = 0x04;
delay_s(2);
portc = 0x08;
delay_s(2);

It may also be worth using the above code for say PortB just to ensure that the program is actually running.

LEDs connected to PortB will share connections with the LCD and as such will do strange looking things when the program is running.