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How do you read Wiegand Keypad? — Parallax Forums

How do you read Wiegand Keypad?

T ChapT Chap Posts: 4,094
edited 2022-11-27 14:36 in General Discussion

Hello all. I have a Prop 1 controller with a special request to add a standard 26B Wiegand keypad for code only access, no card. 4-6 digits. The idea is to have on the controller side some method via GUI or Menu on my P1 board to set the code length ie 4 digits, and have the ability to create a few different codes. ie 1234 for some, 5678 for others. Looking at all the Wiegand access control panels, it is not a simple matter to find out even how to buy a keypad and controller that can be configured how I need: read the codes from the keypad, if a known code comes in, trigger a normally open contact, 500millisecond duration. Many wont do pin only. I am ok getting a third party controller to work with the keypad options the end users want to use.

Any suggestions on this?


  • JonnyMacJonnyMac Posts: 8,406
    edited 2022-11-27 20:05

    The attached object will do the trick. I used it to create card & keyboard reader on the P1 while working at a cyber-security firm a few years ago. We used it with this RFID/Keypad combo to read cards and the keys.

    Everything is returned from the background PASM as a bit stream. Keys are treated as individual entities of 4 bits, so you'll have to create code in your app that either uses an ending key (e.g., #) a timeout, or both to collect a string of key presses that you can interpret as a command.

    Looking through the code, I can see a few areas to be improved, but as I don't have my reader handy, I don't want to change anything without testing. This code did work and we used it to read HID cards and accept keypad input.

  • Awesome Jon! I'll check this out. That would be slick to just have inputs on my existing board. I will study what a schematic needs to look like on the Prop side at the inputs.

  • On a board I have already built I had added some spare inputs for an I2C device, using an I2c Extender chip called P82B96TD,118 which allows I2C to run over long lines. I think that by experimenting with Pullups this may work as a nice buffer for the Wiegand, especially since there are no other spare inputs to use short of building a new board.

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