Ports interacting?? 16F1826

[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.