Ports interacting?? 16F1826

[HenrikOlsson]

Hi,
I don't think you can delete a thread and I don't think you should, but that's my personal thoughts of course.
Instead post what the problem was, how you found it and how you solved it. That way others can read about it and perhaps learn something - which is what a forum like this is all about.

Was it perhaps a R-M-W issue?

/Henrik.

[SOTASOTA]

Hi,
I don't think you can delete a thread and I don't think you should, but that's my personal thoughts of course.
Instead post what the problem was, how you found it and how you solved it. That way others can read about it and perhaps learn something - which is what a forum like this is all about.

Was it perhaps a R-M-W issue?

/Henrik.

Good point Henrik! I thought it was a bad circuit board, that is why I thought the thread should be forgotten. However, it ended up being a bad LED. :-)

[mark_s]

Keep in mind

All of the new "Enhanced 12FXXXX and 16FXXXX" parts use the LATx register for changing the output state. Portx register for reading the input state.

[SOTASOTA]

Keep in mind

All of the new "Enhanced 12FXXXX and 16FXXXX" parts use the LATx register for changing the output state. Portx register for reading the input state.

I would like to know more about "LATs". Know zero. Does PIC Basic Pro support these? Tell me more please! Sounds interesting!!

[mark_s]

I would like to know more about "LATs". Know zero. Does PIC Basic Pro support these? Tell me more please! Sounds interesting!!

Hi,

Lat is short for latch. I not a good communicator, so I can't explain it better than the data sheet. The main thing to understand is that on the older pic16's we used portx.x to read or write to a pin. This could lead to R-M-W problem that Henrik pointed out. On the new pic16fxxxx,pic12fxxxx, pic18, dspic, and pic32 we use Latx.x to change the output. Portx.x is used to read a port pin. So on the above code you provided.

Low PORTA.1 
Low PORTA.4 

PORTA.1 = 1
pause 1000
PORTA.4 = 1
pause 1000
PORTA.4 = 0
PORTA.1 = 1

This is how it should be, as someone pointed out in the other thread.

Low LATA.1 
Low LATA.4 

LATA.1 = 1
pause 1000
LATA.4 = 1
pause 1000
LATA.4 = 0
LATA.1 = 1

Here a similar thread

http://www.picbasic.co.uk/forum/showthread.php?t=15836

[HenrikOlsson]

Hi,
Just to clarify, writing to the PORT registers still works on ALL devices. The thing is that newer devices can run much faster (64MHz) compared to older (20MHz) so the risk of running into RMW issues are bigger.

Using the LAT register (when available) for outputs is a good idea. However, I'm not entirely sure that using HIGH/LOW (or any high level pin/port command) on LAT works, actually I don't think it does, but I'd be happy to stand corrected on that.

/Henrik.

[SOTASOTA]

Hi,
I don't think you can delete a thread and I don't think you should, but that's my personal thoughts of course.
Instead post what the problem was, how you found it and how you solved it. That way others can read about it and perhaps learn something - which is what a forum like this is all about.

Was it perhaps a R-M-W issue?

/Henrik.

I also see that I probably ran into a R-M-W issue as well...or got it to work in an unstable state. Good info!!!!!!! Thanks!!! Again, new to R-M-W. Cool.