Using Keypad on ESP8266 (pulldown on pins not supported)

[espruino-discuss]

Posted at 2017-08-29 by n00b

Has anyone ever successfully used a 4x4 switch matrix on ESP8266? Since ESP8266 doesn't support "input_pulldown" on its pins in Espruino, the module from http://www.espruino.com/modules/KeyPad.js doesn't work. Is it possible to modify that module to use "input_pullup" instead?

[espruino-discuss]

Posted at 2017-08-29 by @gfwilliams

You could just copy the code right into your main code? So change:

exports.connect = function (columns, rows, callback) {

to:

var keypad_connect = function (columns, rows, callback) {

and then use keypad_connect(...) instead of require("KeyPad") - hope that helps!

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Posted at 2017-08-29 by n00b

Thanks for the reply @gfwilliams. Sorry I wasn't clear, I tried to do that but I couldn't understand the keypad.js enough to successfully modify it for ESP8266. I tried to switch all the "input_pulldown" to "input_pullup" and set the rows to low instead of high but no dice. Any hint on how to accomplish this in general? Thanks again!

PS. Kudos & great work with Espruino! made MCU development so accessible to an old JS hack like me :) I bought all 3 variants of the official espruino board, but planning to use NodeMCU boards as "throwaway" project boards.

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Posted at 2017-08-29 by @gfwilliams

Wow, thanks!

Ahh, ok - yes, I'm pretty sure it is possible. What about this:

function (columns, rows, callback) {
  var watches = [];
  var lastState = 0;
  var readState = function() {
    var press = -1;
    for (var i in rows) {
      digitalWrite(rows, 0xFFFFFFFF ^ (1 << i));
      var v = digitalRead(columns);
      for (var j in columns)
        if (!(v & (1<<j)))
          press = j+i*columns.length;
    }
    // reset state
    digitalWrite(rows, 0);
    return press;
  };
  var setup = function() {
    for (var i in columns) pinMode(columns[i], "input_pullup");
    digitalWrite(rows, 0);
  };
  var onWatch = function() {
    var s = digitalRead(columns);
    if (s!=lastState) {
      lastState = s;
      removeWatches();
      var c = readState();
      addWatches();
      if (c>=0) callback(c);
    }
  };
  var addWatches = function() {
    for (var i in columns)
      watches[i] = setWatch(onWatch, columns[i], { repeat:true, edge:"both" });
  };
  var removeWatches = function() {
    for (var i in watches)
      clearWatch(watches[i]);
  };
  setup();
  if (callback!==undefined) addWatches();
  return {
    read: readState
  };
};

I haven't tried it but I think it's ok - basically I had to invert everything, any time a pin was written or read.

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Posted at 2017-08-29 by n00b

That works perfect!! Thanks, you're the best!