Need help in matrix keypad coding

[skimask]

Rano, don't worry about Skimask. This is his own way to tell you...

Good one...
What I was getting at was the fact that the O/P said he 'found the code on the internet' and didn't know how to make it do what he needed it to do...suggesting that maybe the O/P dove in head first, maybe without so much as first creating a 'blinky' and working up from there. 'cause quite frankly, that fix up there a couple of posts back is a very basic fix (change should be the operative word here).
In other words, I think a fish has been given...and more fish might soon be handed out...

[T.Jackson]

In other words, I think a fish has been given...and more fish might soon be handed out...

Don't you go stealing my fish, I'm not very good at sharing

[skimask]

Don't you go stealing my fish, I'm not very good at sharing

You got fish? Sounds like a slogan for something...

Got Fish?

[T.Jackson]

Got Fish?

After studying applied reasoning I can't help but wonder if maybe I do.

[rano_zen06]

It's ok skimask, I understand what you're trying to say. I'm just new in the world of PIC and know nothing about it.Now I need to deal with PIC to finish my project. So, I just do reverse Engineering..study the codes given and learn how it function.

[Probotics]

All right I've seen this code a bit now and I have to admit I don't know WHY it works. I do know that may or may not work if you change the port (that's informative I know) which might be related to some weak pull up issue (?) or some other circuit design point I missed.

Here's the question - This code sets all values of the portD to zero

' Wait for keypress
For col = 0 to 3 ' 4 columns in keypad
PORTD = 0 ' All output pins low
TRISD = (dcd col) ^ $ff ' Set one column pin to output
row = PORTD >> 4 ' Read row
If row != $f Then gotkey ' If any keydown, exit


then changes the direction of one pin/column at a time to output instead of input. Great. The question is: why by simply changing the pin to output does the value of that pin go from low (portd=0) to high?

[tenaja]

The output state of the pin is stored, even when it is an input. When you make it an input, it automatically goes wherever the input is pulling it. As soon as you make it an output, the old output value is restored.

The way to ensure it goes to the desired state is to set the value prior to TRISing it to an output.