ekryski / raspi-io

An IO plugin for Johnny-Five that provides support for the Raspberry Pi

Raspi-io

Raspi-io is a Firmata API compatible library for Raspbian running on the Raspberry Pi that can be used as an I/O plugin with Johnny-Five. The API docs for this module can be found on the Johnny-Five Wiki. Raspi IO supports the Model B Rev 1, Model B Rev 2, Model A+, Model B+, and Raspberry Pi 2 Model B, but does not support the Model A.

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

System Requirements

• Raspberry Pi Model B Rev 1 or newer (sorry Model A users)
• Raspbian Wheezy 2015-05-05 or Raspbian Jesse
  • See nebrius#24 for more info about support for other OSes
• Node 0.10 or Node 0.12
  • See nebrius#35 for more info about Node 4 support

Installation

Install with NPM:

npm install raspi-io

Warning: this module requires GCC 4.8 or newer. This means that you should be running Raspbian Jesse or newer, released in September of 2015.

Usage

Using raspi-io inside of Johnny-Five is pretty straightforward, although does take an extra step compared to the Arduino Uno:

var raspi = require('raspi-io');
var five = require('johnny-five');
var board = new five.Board({
  io: new raspi()
});

board.on('ready', function() {

  // Create an Led on pin 7 (GPIO4) on P1 and strobe it on/off
  // Optionally set the speed; defaults to 100ms
  (new five.Led('P1-7')).strobe();

});

The io property must be specified explicitly to differentiate from trying to control, say, an Arduino Uno that is plugged into the Raspberry Pi. Note that we specify the pin as "P1-7", not 7. See the section on pins below for an explanation of the pin numbering scheme on the Raspberry Pi.

Note: This module is not intended to be used directly. If you do not want to use Johnny-Five, I recommend taking a look at Raspi.js, which underpins this library and is a little more straight-forward to use than using raspi-io directly.

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.

I2C notes

There are a few limitations and extra steps to be aware of when using I2C on the Raspberry Pi.

First, note that the I2C pins can only be used for I2C with Raspi IO, even though they are capable of GPIO at the hardware level.

Also note that you will need to edit /boot/config.txt in order to change the I2C baud rate from the default, if you need to. If you notice that behavior is unstable while trying to communicate with another microcontroller, try setting the baudrate to 10000 from the default 100000. This instability has been observed on the Arduino Nano before.

Finally, if you try to access a device that doesn't exist, you will get an error stating EIO, i/o error (sorry it's not very descriptive).

License

The MIT License (MIT)

Copyright (c) 2013-2014 Bryan Hughes [email protected]

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.