Newb push-button question

willdabeast

Hi all. I'm trying to get a push button to cycle thru 4 choices. I will make the sub-routines later, but for now I'm just trying to get the button to work. I've tried using the button command, but it was making my head hurt.
Here's the code I have:

i VAR Byte
btn PIN 2

Main:

DO
INPUT btn

IF btn = 1 THEN i=i+1
SELECT i
CASE i=1
DEBUG "one"
CASE i=2
DEBUG "two"
CASE i=3
DEBUG "three"
CASE i=4
DEBUG "four"
ENDSELECT
IF btn = 0 THEN i=i
IF i=5 THEN i=1
LOOP

I have it inside a DO/LOOP because I need it to run for a long time.
I know my physical assembly of the cct is working, so something ain't right with the code.
Thanks,
-Will

GeorgeL

Check that the pin is trully pin 2. On the boe-bot board and its variants, the first pin is PIN 0

GeorgeL

Also, do you need this "IF btn = 0 THEN i=i"

willdabeast

I have it hooked up to pin 2 because 0 and 1 are otherwise occupied. As for that last line...now that I look at it I think it is pointless. I deleted it, but the button still doesn't work.
-Will

Franklin

Try if i > 4 then i = 1

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- Stephen

willdabeast

Isn't "if i>4 then i=1"
the same as "if i=5 then i=1"

They both check to see if i = 5.
If it does, it sets i to 1
If it doesn't it lets i stay the same.

-Will

Franklin

No they are not the same. 5 is a finite number so if i = 6 it will fail. but your button may (will) bounce and you may have a number of any size in i. If you still think they are the same I'll give you $5 for $1000 (>$4)

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- Stephen

vaclav_sal

check syntax of SELECT .
Your code is assigning values to variable i instead of evaluating it.
It should reed

SELECT i
· CASE 1
···· DEBUG "One"
.....


IF btn = 1 THEN i=i+1
SELECT i
CASE i=1
DEBUG "one"
CASE i=2
DEBUG "two"
CASE i=3
DEBUG "three"
CASE i=4
DEBUG "four"
ENDSELECT
IF btn = 0 THEN i=i
IF i=5 THEN i=1
LOOP

willdabeast

ahhhh bouncing.
That does make since. I overlooked the little fact it may skip over 5.
I think I'll add a latch to debounce the button.
Thanks.
-Will

willdabeast

OK. I made the previously mentioned change to the code; however I'm still getting nothing on the debug screen when I push the button.
Any ideas?
-Will

Franklin

did you make the change vaclav_sal mentioned?

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- Stephen

willdabeast

That is a bit odd. I must have had this reply window open while vaclav_sal posted his reply.
Anyway. Thank you both for the input. The button works although it repeats endlessly. I think I know where the problem is.
Thanks again.
-Will

MrBi11

you need to make it trigger on only the leading edge of the button press
[noparse][[/noparse]single shot controlled by flg variable]

do
if in2=1 then
 if flg=0 then
  btn=btn+1
  if btn>4 then btn=1
  select case btn
     case 1
         ....
     case 4
  endsel
  flg=1
 endif
else
 flg=0
endif
loop

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