Adds support for optional RESET pin

Author: andrewn

README.md

@@ -6,12 +6,15 @@ The CAP1188 is an 8-channel capacitive touch sensor and is available in a handy
 
 You can wire this up as follows:
 
-| Device Pin | Pi                                                |
-| ---------- | ------------------------------------------------- |
-| 1 (GND)    | [Ground](https://pinout.xyz/pinout/ground)        |
-| 2 (VIN)    | [3.3v](https://pinout.xyz/pinout/pin1_3v3_power)  |
-| 3 (SDA)    | [BCM 2/SDA](https://pinout.xyz/pinout/pin3_gpio2) |
-| 4 (SCK)    | [BCM 3/SCL](https://pinout.xyz/pinout/pin5_gpio3) |
+| Device Pin | Pi                                                              |
+| ---------- | --------------------------------------------------------------- |
+| 1 (GND)    | [Ground](https://pinout.xyz/pinout/ground)                      |
+| 2 (VIN)    | [3.3v](https://pinout.xyz/pinout/pin1_3v3_power)                |
+| 3 (SDA)    | [BCM 2/SDA](https://pinout.xyz/pinout/pin3_gpio2)               |
+| 4 (SCK)    | [BCM 3/SCL](https://pinout.xyz/pinout/pin5_gpio3)               |
+| RST        | [BCM 17 (0)](https://pinout.xyz/pinout/pin11_gpio17) Optional\* |
+
+* Any GPIO pin can be used, see [Reset]() below.
 
 ## Install
 
@@ -50,6 +53,21 @@ connect().then(cap1188 => {
 
 See the [`examples`](./examples) directory for more examples.
 
+### Reset
+
+Optionally, you can connect the reset pin on the board (marked RST), to a pin on the Pi. Call the `reset()` method to reinitialize the sensor which can recalibrate it instead of having to cycle the power. A Promise is returned that resolves when the board has been reset.
+
+See [this page about how to specify a pin](https://github.com/nebrius/raspi-gpio#pin-naming).
+
+In addition, the `reset` event is also emitted.
+
+```
+var cap = require("CAP1188").connect(I2C1, { resetPin: 0 }); // using WiringPi number for BCM17
+cap.reset(function () {
+  // the board has been reset
+});
+```
+
 ## GUI
 
 There's a tiny GUI you can run:

examples/cap1188-events.js

@@ -3,12 +3,18 @@ const connect = require("../").connect;
 // Connect to the CAP1188 breakout.
 // Returns a promise that resolves to the
 // CAP1188 instance when it's ready.
-const connectionPromise = connect();
+const connectionPromise = connect({ resetPin: 0 });
 
 // When it's ready, add a listener that emits
 // when a touch is registered
 connectionPromise.then(cap1188 => {
   cap1188.on("change", function(evt) {
     console.log(evt);
   });
-});
+
+  cap1188.on("reset", function(evt) {
+    console.log("reset");
+  });
+
+  cap1188.reset();
+}, console.error);

index.js

@@ -1,12 +1,12 @@
-const init = require('raspi').init;
-const I2C = require('raspi-i2c').I2C;
+const init = require("raspi").init;
+const I2C = require("raspi-i2c").I2C;
 
-const connect = require('./lib/CAP1188').connect;
+const connect = require("./lib/CAP1188").connect;
 
-module.exports.connect = ({ i2c = new I2C() } = {}) => {
+module.exports.connect = ({ i2c = new I2C(), ...opts } = {}) => {
   return new Promise((resolve, reject) => {
     init(() => {
-      const cap1188 = connect(i2c);
+      const cap1188 = connect(i2c, opts);
       resolve(cap1188);
     });
   });

lib/CAP1188.js

@@ -8,6 +8,8 @@
     http://www.espruino.com/CAP1188
 */
 const EventEmitter = require("events").EventEmitter;
+const gpio = require("raspi-gpio");
+const createPromiseTimeout = require("./createPromiseTimeout");
 
 var C = {
   ADDRESS_DEFAULT: 0x29
@@ -40,13 +42,24 @@ class CAP1188 extends EventEmitter {
       this.addr = _opts;
     } else {
       this.addr = _opts.address || C.ADDRESS_DEFAULT;
-      this.resetPin = _opts.resetPin || null;
+      this.resetPin =
+        _opts.resetPin != null ? new gpio.DigitalOutput(_opts.resetPin) : null;
     }
 
     this.pollingIntervalMs = _opts.pollingIntervalMs || 500;
     this.pollingId = null;
     this.lastTouches = [false, false, false, false, false, false, false, false];
 
+    this.scheduleTouchPoll = this.scheduleTouchPoll.bind(this);
+
+    // Begin polling touches when a "change" listener is
+    // registered
+    this.on("newListener", function(eventName) {
+      if (eventName === "change" && this.pollingId == null) {
+        this.scheduleTouchPoll();
+      }
+    });
+
     this.initialize();
   }
 
@@ -56,19 +69,13 @@ class CAP1188 extends EventEmitter {
     this.multipleTouches(true);
     // "Speed up a bit"
     this.i2c.writeSync(this.addr, R.STANDBY_CONFIG, Buffer.from([0x30]));
-
-    this.scheduleTouchPoll = this.scheduleTouchPoll.bind(this);
-
-    // Begin polling touches when a listener is
-    // registered
-    this.once("newListener", this.scheduleTouchPoll);
   }
 
   /* Begins polling for touches and
     emits events when they change */
   scheduleTouchPoll() {
     this.readTouchesAndEmit();
-    setTimeout(this.scheduleTouchPoll, this.pollingIntervalMs);
+    this.pollingId = setTimeout(this.scheduleTouchPoll, this.pollingIntervalMs);
   }
 
   readTouchesAndEmit() {
@@ -129,6 +136,42 @@ class CAP1188 extends EventEmitter {
     return touches;
   }
 
+  /* Reset the chip if a reset pin has been specified */
+  reset() {
+    const delay = 100;
+    const pin = this.resetPin;
+    const self = this;
+
+    if (pin == null) {
+      throw new Error("CAP1188 reset called but no resetPin given");
+    }
+
+    const timeout = createPromiseTimeout(delay);
+
+    const writeHigh = function() {
+      pin.write(gpio.HIGH);
+    };
+
+    const writeLow = function() {
+      pin.write(gpio.LOW);
+    };
+
+    return new Promise(function(resolve, reject) {
+      writeLow();
+      timeout()
+        .then(writeHigh)
+        .then(timeout)
+        .then(writeLow)
+        .then(timeout)
+        .then(function() {
+          self.initialize();
+          self.emit("reset");
+          resolve();
+        })
+        .catch(reject);
+    });
+  }
+
   /*  */
   getBit(byt, position) {
     return 1 == ((byt >> position) & 1);

lib/createPromiseTimeout.js

@@ -0,0 +1,7 @@
+module.exports = function(delay) {
+  return function() {
+    return new Promise(function(resolve) {
+      setTimeout(resolve, delay);
+    });
+  };
+};

package-lock.json

@@ -1,8 +1,7 @@
 {
   "name": "raspi-cap",
   "version": "0.0.2",
-  "description":
-    "Raspberry Pi / Node.js module for the CAP1188 capacitive touch breakout ",
+  "description": "Raspberry Pi / Node.js module for the CAP1188 capacitive touch breakout ",
   "main": "index.js",
   "bin": {
     "raspi-cap-debug": "./bin/cap1188"
@@ -14,12 +13,19 @@
   "bugs": {
     "url": "https://github.com/andrewn/raspi-cap/issues"
   },
-  "os": ["linux"],
-  "keywords": ["raspberry pi", "cap1188", "touch"],
+  "os": [
+    "linux"
+  ],
+  "keywords": [
+    "raspberry pi",
+    "cap1188",
+    "touch"
+  ],
   "author": "Andrew Nicolaou <[email protected]>",
   "license": "Apache-2.0",
   "dependencies": {
     "raspi": "^5.0.2",
+    "raspi-gpio": "^5.0.0",
     "raspi-i2c": "^6.1.0"
   }
 }