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Raspi GPIO

Raspi GPIO is part of the Raspi.js suite of libraries that provides access to the hardware GPIO pins on a Raspberry Pi.

If you have a bug report, feature request, or wish to contribute code, please be sure to check out the Raspi IO Contributing Guide.

System Requirements

Raspberry Pi Model B Rev 1 or newer (sorry Model A users)
Raspbian Jessie or newer
- Node-RED works, but can be finicky and difficult to debug.
- See https://github.com/nebrius/raspi-io/issues/24 for more info about support for other OSes
Node 6.4.0 or newer

Detailed instructions for getting a Raspberry Pi ready for NodeBots, including how to install Node.js, can be found in the wiki

Installation

First, be sure that you have installed Raspi.js.

Install with npm:

npm install raspi-gpio

Note: this project is written in TypeScript and includes type definitions in the package.json file. This means that if you want to use it from TypeScript, you don't need to install a separate @types module.

Example Usage

In TypeScript/ES6:

import { init } from 'raspi';
import { DigitalInput, DigitalOutput, PULL_UP } from 'raspi-gpio';

init(() => {
  const input = new DigitalInput({
    pin: 'P1-3',
    pullResistor: PULL_UP
  });

  const output = new DigitalOutput('P1-5');

  output.write(input.read());
});

In JavaScript:

const raspi = require('raspi');
const gpio = require('raspi-gpio');

raspi.init(() => {
  const input = new gpio.DigitalInput({
    pin: 'P1-3',
    pullResistor: gpio.PULL_UP
  });

  const output = new gpio.DigitalOutput('P1-5');

  output.write(input.read());
});

Pin Naming

The pins on the Raspberry Pi are a little complicated. There are multiple headers on some Raspberry Pis with extra pins, and the pin numbers are not consistent between Raspberry Pi board versions.

To help make it easier, you can specify pins in three ways. The first is to specify the pin by function, e.g. 'GPIO18'. The second way is to specify by pin number, which is specified in the form "P[header]-[pin]", e.g. 'P1-7'. The final way is specify the Wiring Pi virtual pin number, e.g. 7. If you specify a number instead of a string, it is assumed to be a Wiring Pi number.

Be sure to read the full list of pins on the supported models of the Raspberry Pi.

API

Module Constants

<table> <thead> <tr> <th>Constant</th> <th>Description</th> </tr> </thead> <tr> <td>LOW</td> <td>A logic low value, one of the two possible return values from digital reads and arguments to digital writes</td> </tr> <tr> <td>HIGH</td> <td>A logic high value, one of the two possible return values from digital reads and arguments to digital writes</td> </tr> <tr> <td>PULL_NONE</td> <td>Do not use a pull up or pull down resistor with a pin, one of the three possible values for the <code>pullResistor</code> in the pin configuration object.</td> </tr> <tr> <td>PULL_DOWN</td> <td>Use the internal pull down resistor for a pin, one of the three possible values for the <code>pullResistor</code> in the pin configuration object.</td> </tr> <tr> <td>PULL_UP</td> <td>Use the internal pull up resistor for a pin, one of the three possible values for the <code>pullResistor</code> in the pin configuration object.</td> </tr> <tr> <td>module</td> <td>An easily consumable object for indirectly passing this module around. Intended specifically for use by Core IO (details coming soon)</td> </tr> <tr> <td></td> <td><table> <thead> <tr> <th>Property</th> <th>Type</th> <th>Description</th> </tr> </thead> <tr> <td>PULL_NONE</td> <td>Constant</td> <td>Alias of PULL_NONE module export.</td> </tr> <tr> <td>PULL_DOWN</td> <td>Constant</td> <td>Alias of PULL_DOWN module export.</td> </tr> <tr> <td>PULL_UP</td> <td>Constant</td> <td>Alias of PULL_UP module export.</td> </tr> <tr> <td>createDigitaInput(config)</td> <td>String | Number | Object</td> <td>See the <a href="#new-digitalinputconfig">DigitalInput constructor</a> for details</td> </tr> <tr> <td>createDigitaOutput(config)</td> <td>String | Number | Object</td> <td>See the <a href="#new-digitaloutputconfig">DigitalOutput constructor</a> for details</td> </tr> </table></td> </tr> </table>

new DigitalInput(config)

Instantiates a new GPIO input instance.

Arguments:

<table> <thead> <tr> <th>Argument</th> <th>Type</th> <th>Description</th> </tr> </thead> <tr> <td>config</td> <td>Number | String | Object</td> <td>The configuration for the GPIO pin. If the config is a number or string, it is assumed to be the pin number for the peripheral. If it is an object, the following properties are supported:</td> </tr> <tr> <td></td> <td colspan="2"> <table> <thead> <tr> <th>Property</th> <th>Type</th> <th>Description</th> </tr> </thead> <tr> <td>pin</td> <td>Number | String</td> <td>The pin number or descriptor for the peripheral</td> </tr> <tr> <td>pullResistor (optional)</td> <td><code>PULL_NONE</code> | <code>PULL_DOWN</code> | <code>PULL_UP</code></td> <td>Which internal pull resistor to enable, if any. Defaults to <code>PULL_NONE</code></td> </tr> </table> </td> </tr> </table>

DigitalInput Instance Properties

value (read-only)

The current value on the pin.

Type: LOW | HIGH

DigitalInput Instance Methods

read()

Reads the current value on the pin.

Arguments: None

Returns: LOW or HIGH

DigitalInput Instance Events

on('change', function(value))

Fired whenever the value of the GPIO pin changes.

Callback Arguments:

<table> <thead> <tr> <th>Argument</th> <th>Type</th> <th>Description</th> </tr> </thead> <tr> <td>value</td> <td><code>LOW</code> | <code>HIGH</code></td> <td>The current value of the GPIO pin.</td> </tr> </table>

new DigitalOutput(config)

Instantiates a new GPIO output instance.

Arguments:

<table> <thead> <tr> <th>Argument</th> <th>Type</th> <th>Description</th> </tr> </thead> <tr> <td>config</td> <td>Number | String | Object</td> <td>The configuration for the GPIO pin. If the config is a number or string, it is assumed to be the pin number for the peripheral. If it is an object, the following properties are supported:</td> </tr> <tr> <td></td> <td colspan="2"> <table> <thead> <tr> <th>Property</th> <th>Type</th> <th>Description</th> </tr> </thead> <tr> <td>pin</td> <td>Number | String</td> <td>The pin number for the peripheral</td> </tr> <tr> <td>pullResistor</td> <td><code>PULL_NONE</code> | <code>PULL_DOWN</code> | <code>PULL_UP</code></td> <td>Which internal pull resistor to enable, if any. Defaults to <code>PULL_NONE</code></td> </tr> </table> </td> </tr> </table>

DigitalOutput Instance Properties

value (read-only)

The current value on the pin, equal to the previous written value.

Type: LOW | HIGH

DigitalOutput Instance Methods

write(value)

Writes the given value to the pin.

Arguments:

<table> <thead> <tr> <th>Argument</th> <th>Type</th> <th>Description</th> </tr> </thead> <tr> <td>value</td> <td><code>LOW</code> | <code>HIGH</code></td> <td>The value to write to the pin</td> </tr> </table>

Returns: None

DigitalOutput Instance Events

on('change', function(value))

Fired whenever the value of the GPIO pin changes.

Callback Arguments:

License

The MIT License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.