MPR121 12-Channel Capacitive Sensor (I2C) module

Author: opichals

devices/MPR121.js

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+/* Copyright (c) 2017 Standa Opichal, Gordon Williams. See the file LICENSE for copying permission. */
+/*
+  Module for the MPR121 12-Channel Capacitive Sensor (I2C)
+
+  Based on the http://sonnycruz.blogspot.cz/2014/07/espruino.html code snippet
+  and other available libraries https://github.com/adafruit?q=MPR121 libraries
+```
+I2C1.setup({scl:B6,sda:B7});
+
+function ready() {
+    setTimeout(function() {
+        var keys = mpr.touched();
+        console.log("Touched: " + keys);
+    }, 200);
+}
+
+var mpr = require("MPR121").connect(I2C1, ready);
+// or
+var mpr = require("MPR121").connect(I2C1, ready, { address: 0x5B });
+
+```
+
+Default address is 0x5A, if tied to 3.3V its 0x5B
+If tied to SDA its 0x5C and if SCL then 0x5D
+*/
+exports.connect = (i2c, callback, options) => {
+  options = options || {};
+
+  let addr = options.address || 0x5A; // default address
+
+  let MPR = {
+    read: (count) => i2c.readFrom(addr, count),
+    write: (data) => i2c.writeTo(addr, data),
+
+    touched: () => {
+      i2c.writeTo(addr, 0x00);
+      var data = i2c.readFrom(addr, 2);
+      return (data[1] << 8) || data[0];
+    },
+
+    setThresholds: (touch, release) => {
+      for (i=0; i<24; i+=2) {
+        i2c.writeTo(addr, 0x41+i, touch);
+        i2c.writeTo(addr, 0x42+i, release);
+      }
+    }
+  };
+
+  // disable electrodes
+  i2c.writeTo(addr, [0x5E,0x00]);
+
+  i2c.writeTo(addr, [0x2B,0x01]);
+  i2c.writeTo(addr, [0x2C,0x01]);
+  i2c.writeTo(addr, [0x2D,0x00]);
+  i2c.writeTo(addr, [0x2E,0x00]);
+
+  i2c.writeTo(addr, [0x2F,0x01]);
+  i2c.writeTo(addr, [0x30,0x01]);
+  i2c.writeTo(addr, [0x31,0xFF]);
+  i2c.writeTo(addr, [0x32,0x02]);
+
+  // touch, release thresholds
+  MPR.setThresholds(15, 8);
+
+  // 0x10: 16uA charge current
+  // 0x20: 32uA charge current (default)
+  i2c.writeTo(addr, [0x5C, options.config1 || 0x20]);
+  // 0x20: 0.5us encoding, 1ms period
+  // 0x3A: 0.5us encoding, 18 samples, 4ms period (default)
+  i2c.writeTo(addr, [0x5D, options.config2 || 0x20]);
+
+  // enable all electrodes
+  i2c.writeTo(addr, [0x5E,0x8F]);
+
+  if (callback) callback(MPR);
+  return MPR;
+};
+

devices/MPR121.md

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+<!--- Copyright (c) 2017 Standa Opichal. Released under the MIT license. -->
+Module for the MPR121 12-Channel Capacitive Sensor (I2C)
+=====================
+
+<span style="color:red">:warning: **Please view the correctly rendered version of this page at https://www.espruino.com/MPR121. Links, lists, videos, search, and other features will not work correctly when viewed on GitHub** :warning:</span>
+
+* KEYWORDS: Module,MPR121,touch,capacitative
+
+Use the [MPR121](/modules/MPR121.js) ([About Modules](/Modules)) module for reading which of the MPR121's 12 electrodes are touched
+=====================
+
+This module communicates with the chip over I2C.
+
+Basic usage:
+
+```
+I2C1.setup({scl:B6,sda:B7});
+
+function ready() {
+    setTimeout(function() {
+        var keys = mpr.touched();
+        console.log("Touched: " + keys);
+    }, 200);
+}
+
+var mpr = require("MPR121").connect(I2C1, ready);
+// or
+var mpr = require("MPR121").connect(I2C1, ready, { address: 0x5B });
+```
+
+**MPR121 module functions**
+
+**touched()** - gives back a 12bit number where each high bit is an activated electrode/key
+
+**setThresholds()** - sets the press/release treshold values
+
+**write()** - writes the provided data (array) to the i2c bus
+
+**read()** - reads the given number of bytes from the i2c bus