read tris register

dan king · Joined: 22 Sep 2003 Posts: 119

Is there a way to read the tris register before setting it so a particular ports direction can be changed without affecting the other ports?

Say I want to change c.2 to output after it had been set to input without affecting any others, such as c.1, c.3, c.4 ,....

Question

asjad · Posted: Wed Apr 07, 2004 3:52 pm

If you insert

#byte TRISC xxxxx

Where xxxxx is the address of TRISC in the actual PIC you are using
(look in PIC datasheet -SFR)

you can then read or write to it!

Hope this helps!
_________________
Best Regards

languer · Joined: 09 Jan 2004 Posts: 144 Location: USA

Something like this maybe,

Haplo · Joined: 06 Sep 2003 Posts: 659 Location: Sydney, Australia

I wouldn't recommend this method on PORTC though, because if you have any peripherals on PORTC, CCS will keep a shadow copy of TRISC and it might conflict with what you are doing. Always use set_tris_c() to write back to TRISC, don't do it directly. Look at this post for more info:
http://www.ccsinfo.com/forum/viewtopic.php?t=17970&highlight=

This code would be much better for changing the direction of RC2 to input:

dan king · Joined: 22 Sep 2003 Posts: 119

Thanks for your help, that's great.

Rgds,

Dan