4X4 keypad read

Comments

• deSilva Posts: 2,967

  2007-09-23 14:44 edited 2007-09-23 14:44

  Brian Beckius said...
  Should I be using pull up or pull down resistors on the outputs ! If so what value ?

  
  (1) Hmmm, all the world takes 10k - so you should also... Funny question...
  (2) up or down - well this depends on the active state of your key presses... That's something only you can know!
  (3) Your code

         if ina[noparse][[/noparse]12] == 1
           number := 10 + index
         if ina[noparse][[/noparse]13] == 1
           number := 20 + index
         if ina[noparse][[/noparse]14] == 1
          number := 30 + index
         if ina[noparse][[/noparse]15] == 1
          number := 40 + index
  

  
  
  can be simplified to

    IF INA [noparse][[/noparse]15..12]
       number := INA[noparse][[/noparse]15..12]*10 + index
  
• Skogsgurra Posts: 231

  2007-09-23 14:50 edited 2007-09-23 14:50

  Hello!
  
  Did you really mean to say "out pins are floating"?
  
  If that is so, you may have to look at the dira register and set output bits high.
  
  (No, I didn't check your code. I am sure deSilva did)
  
  ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
• Brian_B Posts: 842

  2007-09-23 15:03 edited 2007-09-23 15:03

  I'm using 4 outputs to select the row of 4 keys . The program makes one output high and then checks to see if a key is pressed , Then it makes the next output high and checks the keys again . Rigth now when I run the program all the leds randomly go off and on with no keys being pressed.
  
  ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
  Thank's Brian
  
  
  www.truckwiz.com
  
  ·"Imagination is more important than knowledge..." ·· Albert Einstein
  
  http://www.diycalculator.com/subroutines.shtml· My favorite website ( Bet you can't guess why)
• Skogsgurra Posts: 231

  2007-09-23 15:41 edited 2007-09-23 15:41

  OK, a multiplexed keyboard. I asked if it is the output pins you were referring to. You do not need any pull-ups (or -downs) on the Prop outputs. They are not open collector.
  
  ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
• Lawson Posts: 870

  2007-09-23 16:14 edited 2007-09-23 16:14

  Do you have a pull-down resistor on the input pins of the Propeller? (needs to be a pull down 'cause the rows are driven high) If you don't have something like a pull-down resistor to define the default (off) state of an input it will float to some random value.
  
  my log($1) cents,
  Marty
  
  ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
  Lunch cures all problems! have you had lunch?
• deSilva Posts: 2,967

  2007-09-23 16:40 edited 2007-09-23 16:40

  Well, before it becomes absolutely confusing here:
  
  (A) Please connect 10k resistors from GND to pins 12 to 15 of your Propeller ("pull down")
  (B) The code

        dira[noparse][[/noparse] 8..11]~~
  ...
    someloop
  ....
        outa[noparse][[/noparse] 8..11]~
        outa[noparse][[/noparse] index]~~
  

  
  
  is no good at all for a simple matrix, as two pressed keys make a shortcut!
  Do

       OUTA[noparse][[/noparse] 8..11] ~~
  ....
    some loop
  ....
        DIRA[noparse][[/noparse] 8..11]~
        DIRA[noparse][[/noparse] index]~~
  

  
  
  instead.
  
  Then it should work!
• Skogsgurra Posts: 231

  2007-09-23 17:01 edited 2007-09-23 17:01

  came to think of that old story about the oldest profession - the one that ends in "and who created chaos?"
  
  ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
• Brian_B Posts: 842

  2007-09-23 18:31 edited 2007-09-23 18:31

  Sorry for the confusion , I somtimes forget that you guys arn't sitting here looking over my shoulder . deSilva , Works perfect ! Thank's
  
  ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
  Thank's Brian
  
  
  www.truckwiz.com
  
  ·"Imagination is more important than knowledge..." ·· Albert Einstein
  
  http://www.diycalculator.com/subroutines.shtml· My favorite website ( Bet you can't guess why)