Updated with new methods

2016-04-05 11:42:41 +00:00
parent 2bdcf41538
commit 75b1a4c9bf
71 changed files with 14055 additions and 403 deletions
@@ -0,0 +1,155 @@
+# gpio - talk to your Raspberry Pi's gpio headers
+
+* demo using LED: http://www.youtube.com/watch?v=2Juo-CJ6eu4
+* demo using RC car: http://www.youtube.com/watch?v=klQdX8-YVaI
+
+
+## Important note
+I haven't maintained this project for a while now, and it's unlikely I will provide any updates going forward given other more mature gpio libraries out there. If you're looking for a reliable way to communicate with the raspberry pi in JavaScript, check out the [wiring-pi JavaScript library](https://www.npmjs.com/package/wiring-pi). It provides direct bindings to the fully-featured [Wiring Pi C library](http://wiringpi.com/).
+
+---
+
+##Installation
+##### Get node.js on your Raspberry Pi
+On Raspbian, you can simply run `apt-get install nodejs`,
+otherwise, [compile it](https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager)
+
+## Usage
+
+This library is an npm package, just define "gpio" in your package.json dependencies or
+```js
+npm install gpio
+```
+
+##### Note: you must be running as root or have the proper priviledges to access the gpio headers
+
+##### Standard setup
+
+```js
+var gpio = require("gpio");
+
+// Calling export with a pin number will export that header and return a gpio header instance
+var gpio4 = gpio.export(4, {
+   // When you export a pin, the default direction is out. This allows you to set
+   // the pin value to either LOW or HIGH (3.3V) from your program.
+   direction: 'out',
+
+   // set the time interval (ms) between each read when watching for value changes
+   // note: this is default to 100, setting value too low will cause high CPU usage
+   interval: 200,
+
+   // Due to the asynchronous nature of exporting a header, you may not be able to
+   // read or write to the header right away. Place your logic in this ready
+   // function to guarantee everything will get fired properly
+   ready: function() {
+   }
+});
+```
+
+##### Header direction "in"
+If you plan to set the header voltage externally, use direction `in` and read value from your program.
+```js
+var gpio = require("gpio");
+var gpio4 = gpio.export(4, {
+   direction: "in",
+   ready: function() {
+   }
+});
+```
+
+##### API Methods
+
+```js
+// sets pin to high
+gpio4.set();
+```
+```js
+// sets pin to low (can also call gpio4.reset())
+gpio4.set(0);
+```
+```js
+// Since setting a value happens asynchronously, this method also takes a
+// callback argument which will get fired after the value is set
+gpio4.set(function() {
+   console.log(gpio4.value);    // should log 1
+});
+gpio4.set(0, function() {
+   console.log(gpio4.value);    // should log 0
+});
+```
+```js
+// unexport program when done
+gpio4.unexport();
+```
+
+##### EventEmitter
+This library uses node's [EventEmitter](http://nodejs.org/api/events.html) which allows you to watch
+for value changes and fire a callback.
+```js
+// bind to the "change" event
+gpio4.on("change", function(val) {
+   // value will report either 1 or 0 (number) when the value changes
+   console.log(val)
+});
+      
+// you can bind multiple events
+var processPin4 = function(val) { console.log(val); };
+gpio4.on("change", processPin4);
+            
+// unbind a particular callback from the "change" event
+gpio4.removeListener("change", processPin4);
+      
+// unbind all callbacks from the "change" event
+gpio4.removeAllListeners("change");
+      
+// you can also manually change the direction anytime after instantiation            
+gpio4.setDirection("out");
+gpio4.setDirection("in");
+```
+
+## Example
+##### Cycle voltage every half a second
+```js
+var gpio = require("gpio");
+var gpio22, gpio4, intervalTimer;
+
+// Flashing lights if LED connected to GPIO22
+gpio22 = gpio.export(22, {
+   ready: function() {
+      intervalTimer = setInterval(function() {
+         gpio22.set();
+         setTimeout(function() { gpio22.reset(); }, 500);
+      }, 1000);
+   }
+});
+
+// Lets assume a different LED is hooked up to pin 4, the following code 
+// will make that LED blink inversely with LED from pin 22 
+gpio4 = gpio.export(4, {
+   ready: function() {
+      // bind to gpio22's change event
+      gpio22.on("change", function(val) {
+         gpio4.set(1 - val); // set gpio4 to the opposite value
+      });
+   }
+});
+
+// reset the headers and unexport after 10 seconds
+setTimeout(function() {
+   clearInterval(intervalTimer);          // stops the voltage cycling
+   gpio22.removeAllListeners('change');   // unbinds change event
+   gpio22.reset();                        // sets header to low
+   gpio22.unexport();                     // unexport the header
+   
+   gpio4.reset();
+   gpio4.unexport(function() {
+      // unexport takes a callback which gets fired as soon as unexporting is done
+      process.exit(); // exits your node program
+   });
+}, 10000)
+```
+
+
+##### Controlling an RC car
+Source code here: https://github.com/EnotionZ/node-rc
+