KeyPad Matrix

Key Pad Key Pad

A KeyPad Matrix is a selection of switches arranged in a grid. One side of each switch is connected with horizontal wires (rows) and one side is connected with vertical wires (columns). By putting a signal on one side (for example the rows) and reading the other side (the columns), you can determine which key is pressed down.

KeyPads are handled by the KeyPad (About Modules) module.

Simply supply two arrays, one of wires connected to columns, one of wires connected to rows.

If a third argument (a callback function) is supplied, watches will be set up, and the callback will be called automatically as soon as a button is pressed. If it isn't, it's up to the user to use to find out what key is pressed. -1 will be returned if no key is pressed.

For example, you could connect the Key Pad in the Ultimate kit to B2,B3,B4,B5,B6,B7,B8 and B9 (they're one long row of pins). The wire nearest the D key could go to B2, and the wire nearest * could go to B9. You'd then use the module as follows:

require("KeyPad").connect([B2,B3,B4,B5],[B6,B7,B8,B9], function(e) {


var keypad = require("KeyPad").connect([B2,B3,B4,B5],[B6,B7,B8,B9]);

With the 4x5 KeyPads (readily availble on ebay), the four wires nearest the F1 key are the columns. For example, it might be hooked up like this:

require("KeyPad").connect([B2,B3,B4,B5],[B6,B7,B8,B9,B12], function(e) {
  print("AB#*123U456D789CL0RE"[e]); //A=F1, B=F2, U/D/L/R = Up/Down/Left/Right, C=ESC, E=Enter

This example uses B12, which also has BTN1 on it - this is fine, though pressing BTN1 will result in spurrious keypresses being recorded.




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