Raspi Serial

Raspi Serial is part of the Raspi.js suite that provides access to UART ports, either the built-in port or a USB add-on port.

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 10.13.0 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.

Install with npm:

npm install raspi-serial

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.

If you are not running a Raspberry Pi without WiFi:

All older versions of the Raspberry Pi enable a TTY console over serial, meaning that you can use the screen command on *NIX computers to log in to the Raspberry Pi over serial. This can get in the way of using the serial port for robotics, however. To disable TTY over serial, do the following:

1. Run sudo raspi-config to start the Raspberry Pi configuration utility
2. Select 5 Interface Options
3. Select P6 Serial Options
4. Select No when asked Would you like a login shell to be accessible over serial?
5. Select Yes when asked Would you like the serial port hardware to be enabled?
6. Select OK
7. Select Finish and select Yes to reboot when prompted

WARNING: If you are running a Raspberry Pi with WiFi:

The Bluetooth module on these Raspberry Pis is controlled using the serial port, meaning it cannot be used directly while also using Bluetooth. Using this module with the default serial port will disable bluetooth!

For an in-depth discussion on why and how to work around it, read https://raspberrypi.stackexchange.com/questions/45570/how-do-i-make-serial-work-on-the-raspberry-pi3.

Example Usage

In TypeScript/ES6:

import { init } from 'raspi';
import { Serial } from 'raspi-serial';
 
init(() => {
  var serial = new Serial();
  serial.open(() => {
    serial.on('data', (data) => {
      process.stdout.write(data);
    });
    serial.write('Hello from raspi-serial');
  });
});

In JavaScript:

const raspi = require('raspi');
const Serial = require('raspi-serial').Serial;
 
raspi.init(() => {
  var serial = new Serial();
  serial.open(() => {
    serial.on('data', (data) => {
      process.stdout.write(data);
    });
    serial.write('Hello from raspi-serial');
  });
});

API

Module Constants

Constant	Description
DEFAULT_PORT	The port ID of the default serial port, equals `"/dev/ttyAMA0"`
PARITY_NONE	Use no parity, one of five possible values for the parity property in the constructor options
PARITY_EVEN	Use even parity, one of five possible values for the parity property in the constructor options
PARITY_ODD	Use odd parity, one of five possible values for the parity property in the constructor options
PARITY_MARK	Use mark parity, one of five possible values for the parity property in the constructor options
PARITY_SPACE	Use space parity, one of five possible values for the parity property in the constructor options
module	An easily consumable object for indirectly passing this module around. Intended specifically for use by Core IO (details coming soon)
	Function Property Type Description createSerial(options) Pass through for the Serial constructor

new Serial(options)

Instantiates a new Serial instance with the given options, defaulting to the built-in UART port. Check the wiring information wiki for more information.

Note: the port is not automatically opened.

Arguments:

Argument	Type	Description
options (optional)	Object	The configuration options.
	Property Type Description portId (optional) String The port to open, defaults to '/dev/ttyAMA0' baudRate (optional) Number The baud rate, defaults to 9600 dataBits (optional) Number The number of data bits in a character, defaults to 8 stopBits (optional) Number The number of stop bits in a character, defaults to 1 parity (optional) PARITY_NONE | PARITY_EVEN | PARITY_ODD | PARITY_MARK | PARITY_SPACE The parity of a character, defaults to PARITY_NONE

Instance Properties

port

The serial port tied to this instance

Type: String

baudRate

The baud rate tied to this instance

Type: Number

dataBits

The number of data bits tied to this instance

Type: Number

stopBits

The number of stop bits tied to this instance

Type: Number

parity

The parity tied to this instance

Type: One of PARITY_NONE, PARITY_EVEN, PARITY_ODD, PARITY_MARK, or PARITY_SPACE

Instance Methods

open(cb)

Open the port.

Arguments:

Argument	Type	Description
cb (optional)	Function	The callback to call once opening is complete
	No arguments

Returns: None

close(cb)

Close the port.

Arguments:

Argument	Type	Description
cb (optional)	Function	The callback to call once closing is complete
	Argument Type Description err String | null The error, if one occurred, else null

Returns: None

write(data, cb)

Write the given data to the serial port.

Arguments:

Argument	Type	Description
data	Buffer | String	The data to write to the port
cb (optional)	Function	The callback to call once writing is complete
	No arguments

Returns: None

flush(cb)

Flushes the serial port.

Arguments:

Argument	Type	Description
cb (optional)	Function	The callback to call once writing is complete
	Argument Type Description err String | null The error, if one occurred, else null

Returns: None

Events

on('data', function(data))

Fired whenever data is received on the serial port.

Callback Arguments:

Argument	Type	Description
data	Buffer	The data read from the serial port.

License

The MIT License (MIT)

Copyright (c) 2014-2017 Bryan Hughes [e-mail]

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.