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building a KeyPad — Parallax Forums

building a KeyPad

ftj405ftj405 Posts: 8
edited 2011-02-07 13:45 in General Discussion
i have an old wireless phone that has the keypad on a seperate board. it has nine connector pins to connect to.

Can anyone tell me what i need to get this to interface to a basic stamp 2 and a propeller..

From the pictures attached, it looks like it has a resistor for each key..

Thanks
KeypadFront.jpg
KeypadBack.jpg
KeypadFront.jpg
1024 x 768 - 48K
KeypadBack.jpg
1024 x 768 - 53K

Comments

  • FranklinFranklin Posts: 4,747
    edited 2011-02-06 19:25
    Get out your ohm meter and do some testing. You should be able to figure it out pretty fast.
  • LeonLeon Posts: 7,620
    edited 2011-02-07 04:49
    I think it uses conductive pads on the keys. It has 18 keys, which ties in with the nine connections - 5 * 4 = 20. One will be ground.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-02-07 13:45
    There's an object (I think it comes with the Prop Tool) for interfacing a 4 x 4 keypad with the Prop. It (your keypad) might work with a modified version of the object.

    When I used the object I had to add 0.1uF capacitors to each column pin to get to work correctly (I think my wires were too long).

    I wrote an object that stores the keypresses until they are asked for by the main object. I can set the time I want the keypress to stay valid so old keypresses can be ignored.

    If you want I'll dust it off and post it. I'm pretty sure I posted it once but the version I posted had some bugs. I never did get the cleaned up version posted to OBEX. Let me know if you're interested in it.

    The 4x4 keypad object should give you a good idea on how to hook up your keypad.
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