PIC's ports individual bits manipulation - how to?

[flotulopex]

I've attached two pictures about what I can see.

The first picture "Before Loop Start" shows that my PORTA.0 to 3 are set to "1". This is because I need them to be at this state before the main loop starts (driving CA Leds).

I did the same for PORTA.6 (=1) just for testing purpose. PORTA.6 will be used for something else in my program if I can handle the actual problem.

When I start the execution of the program, PORTA.6 goes to "0" witch is unwanted here.

Mister_E you're right, using DCD will modify all ports.... Was not a good idea on my side. Thank you for making me aware.

[mister_e]

I should have see it first... You must set the TRIS register, unless those pin are set as input.

MYPORT  var PORTB
Loop    var BYTE
TRISB=0
PORTB.6 = 1 'Test to check port's state change in simulator...

Start:
    for LOOP = 0 to 3
        myport.0[Loop] = 1  'High
        PAUSE 500
        myport.0[loop] = 0  'Low
    next
    goto start
END

[skimask]

I've attached two pictures about what I can see.

The first picture "Before Loop Start" shows that my PORTA.0 to 3 are set to "1". This is because I need them to be at this state before the main loop starts (driving CA Leds).

I did the same for PORTA.6 (=1) just for testing purpose. PORTA.6 will be used for something else in my program if I can handle the actual problem.

When I start the execution of the program, PORTA.6 goes to "0" witch is unwanted here.

Mister_E you're right, using DCD will modify all ports.... Was not a good idea on my side. Thank you for making me aware.

Looks like it might be a bug in the simulator. PortA.6 on the F88 is also OSC2/CLKO. I may have missed something, ya never know. Try it on the real thing and see what happens.

[mister_e]

Never mind.. misread the original code...

[flotulopex]

You may be right!

I just noticed that, using an additional microcontroler view in the simulator, the port doesn't change.

So I'm going to make it in "real".

Another thing; I have declared PORTA.6 as an Input (TRISA = %11110000). When I change this to an Output (TRISA = %10110000), the port will keep it's status as it should be.

Unfortunalety, I will need it as an Input.

I'll go back to my breadboard....

[skimask]

You may be right!

I just noticed that, using an additional microcontroler view in the simulator, the port doesn't change.

So I'm going to make it in "real".

Another thing; I have declared PORTA.6 as an Input (TRISA = %11110000). When I change this to an Output (TRISA = %10110000), the port will keep it's status as it should be.

Unfortunalety, I will need it as an Input.

I'll go back to my breadboard....

Actually, I believe I heard both mister_e and DT both say that they don't trust simulators one bit.
However, I trust the Microchip simulator almost implicitly. Why don't you try running your code on that and keeping an eye on the port values?

[flotulopex]

Well, the simulator I use is wrong. I checked with my logic probe, and this one says true.

Skimask, I have tried to use the MELABS simulator if this is the one you're talking about.

But, compared to the one I use, it was such a hassle to make it work that I abandonned this one.

Is it the one you use?

[Dave]

flotulopex,
INPUTDATA = PORTA >> 4 'LOWER 4 BITS OF INPUTDATA ARE NOW UPPER 4 BITS OR PORTA (INPUT PINS)
PORTA = PORTA & %11110000 'STRIP LOWER 4 BITS OF PORTA
PORTA = PORTA | (DIGIT & %00001111) 'REPLACE LOWER 4 BITS WITH NEW DIGIT DATA

Now your upper 4 bits are stored in variable INPUTDATA. The lower 4 bits of PORTA have just been updated with the lower 4 bits of variable DIGIT.

If I'm incorrect about your original question? I can't think of any easier method.

Dave Purola,
N8NTA

[mister_e]

Flotulopex,
as far as i'm aware of MELABS don't do any Simulator... but i could be wrong.

Skimask talked about the built-in MPLAB simulator (Debugger>Select Tool>>MPLAB Sim) one.

To use it, you need to add some 'Watch' (View>Watch) and then you enjoy seeing them changing.

[flotulopex]

Thanks Dave, this is another way to solve my problem.

Indexing the port may be faster in the loop's execution (I need speed).

[flotulopex]

Right then Mister_e, that's the one I had a hard time to make work...

Maybe I should insist a little more.

The simulator I use is that easy... but maybe not fully reliable so it may be worth to spend more time on the MELABS Sim programmer.