DIP switch select delay

[Bruce]

Hi Joe,

It's a lot simpler than it might look at first glance.

Index = (PORTA >> 2) & $0F ' Read DIP switch AND mask result

By shifting the value read in from the 8-bit porta register right by 2, we're just shifting the 4-bits of interest into the lower 4-bits of the Index variable. Next we AND the intermediate result with %00001111 so the Index variable can never be larger than 15.

We do this because the lookup table has 16 entries. 0 to 15.

LOOKUP2 Index,[200,300,400,500,600,700,800,900,1000,2000,3000,400 0,5000,6000,7000,8000],X

If Index = 0 then 200 is placed in X. If Index = 15 then X = 8000.

If you used RA0 to RA3 for the switches you wouldn't need to shift right by 2 since the switches would be connected to the lower 4-bits of the port. You would still want to AND the result with %00001111 however just to make sure the result in Index never exceeded 15 since the lookup table only has 16 entries. 0 to 15.

You could of course use portb or any other port with at least 4 inputs for your switches.

Say you already had the lower 4-bits of portb being used for something else, and you added 4 switches to RB4 to RB7.

You could do something like Index = (PORTB >> 4) & $0F for the same effect we had above with the lookup table by limiting the result to
0 - 15.

If you use RB0 to RB3 for the switch inputs, then Index = PORTB & $0F is all you would need. The & $0F just makes sure Index stays within range by masking out the upper 4-bits.

[Archangel]

Thanks Bruce !
Now I Get It !
Thanks Also To Mister_e

[skimask]

Thanks Bruce !
Now I Get It !
Thanks Also To Mister_e

I'd save the pins, and use an old pot and the POT command, if tight accuracy wasn't needed anyways.
Save the pins, possibly save some code space, most likely save some PCB space.

[Archangel]

I'd save the pins, and use an old pot and the POT command, if tight accuracy wasn't needed anyways.
Save the pins, possibly save some code space, most likely save some PCB space.

I thought about that, I really want to port this over to a 12F675 for a dedicated gadget. That is why I asked about using the other pins as outputs . . . so much to learn . . . so many cool tricks . . . so many Giving Caring Wonderful people . . . My Thanks!
JS

[skimask]

I thought about that, I really want to port this over to a 12F675 for a dedicated gadget. That is why I asked about using the other pins as outputs . . .

AND, the POT command doesn't require an analog capable pin.
Bonus points...