PIC18F8720 PORTD problem

[Charles Linquis]

I, too, found some real weirdness with early
8720s. They were the only chip big enough to
handle my task, so I couldn't switch to another
device or slow it down. I found myself doing all
sorts of work-arounds to get it to work.

The "late model" (July 2005 and later) 8720s and the
8722's are fine.


Something you might try -
Read PORTD with one instruction

Something like:

PORTDMirror = PortD

channel.bit0 = PORTDMirror.0
channel.bit1 = PORTDMirror.1
channel.bit2 = PORTDMirror.2
channel.bit3 = PORTDMirror.3
...

[nverma]

Markings are as follows:

PIC18F8720
-I/PT
05473PP

And I tried reading the whole port at once aswell. It didn't make any difference. Wow something so simple, I really wonder what the problem is now.

[skimask]

Markings are as follows:

PIC18F8720
-I/PT
05473PP

And I tried reading the whole port at once aswell. It didn't make any difference. Wow something so simple, I really wonder what the problem is now.

Date code of 0547...that makes it a newer revision...

Watchdog timer disabled?

[nverma]

Yes, watchdog timer and low voltage programming disabled. And im running the PIC at 5 V.

[mister_e]

What happen if you do a SEROUT loop and skip the PORT reading?

Which device programmer, PBP and MPASm version are you using?

[nverma]

If I skip reading the port and just do a SEROUT loop, then I always read the initial value that was input on the port at the time of reset. Like I said, if the PIC is reset, it does read the port with the correct inputs. It just doesn't read continuously during the program at every reading. Its almost like the port stop working after reset. I am using melabs programmer v4.10, MicroCode studio v2.3.

[skimask]

If I skip reading the port and just do a SEROUT loop, then I always read the initial value that was input on the port at the time of reset. Like I said, if the PIC is reset, it does read the port with the correct inputs. It just doesn't read continuously during the program at every reading. Its almost like the port stop working after reset. I am using melabs programmer v4.10, MicroCode studio v2.3.

Which version of PBP?