Software UART on ICSP (pgd, pgc) pins

maria100 · Joined: 01 Feb 2012 Posts: 63

Hello, I have tried this as in title, but it does not work. Is this a hardware problem? My PIC is 18F14k50. Thank you.

temtronic · Posted: Sun Apr 22, 2012 9:55 am

I suspect that you may have set ICD=TRUE or are trying to use the debugger, or ICSP.....

You must disable all that 'stuff'...

One of the prime reasons for buying CCS back in '99 was their abilty to use any pins for software UARTs, same still holds true today.

maria100 · Joined: 01 Feb 2012 Posts: 63

I did not set ICD, however I have a permanent MCLR pullup on my board. This could be the cause ?

temtronic · Posted: Tue Apr 24, 2012 6:20 am

No, all my boards have MCLR tied high or disabled in fuses, for decades, as I never use ICSP or ICD or any other 'debugger'.

Ttelmah · Joined: 11 Mar 2010 Posts: 19546

You say you don't select ICD. What are you compiling 'through'?. If perchance, you are using MPLAB, this _defaults_ to enabling ICD. You have to change it's settings to say to compile for release, or it turns ICD on whatever you do....
Might be the problem.

Best Wishes

Ttelmah · Joined: 11 Mar 2010 Posts: 19546

Read the data sheet:
"RA0 and RA1 do not have TRISA bits associated with
them. As digital port pins, they can only function as
digital inputs".

So you can use one of the pins as a software UART RX pin, but you can't generate TX on the other pin.

Best Wishes

maria100 · Joined: 01 Feb 2012 Posts: 63

I was just finishing reading now a other post about this and find that pgd, pgc can be only inputs , heh, even so , thank you for clearing things up once again!