src/serial.js
import {EventEmitter} from 'events'
import SerialPort from 'serialport'
/**
* A node-serialport wrapper that keeps track of port state and allows from on-the-fly
* port path/name changes (automatically attaches/detaches event listeners and keeps config).
*/
export default class Serial extends EventEmitter {
/**
* Constructor: the place for setting the baud rate and parser.
* @param {Function} [parser=raw] A node-serialport parser.
* @param {Number} [baud=19200] Desired baud rate.
*/
constructor(logger, parser, baud = 19200) {
super()
/**
* Holds the current node-serialport instance.
* @type {!SerialPort}
*/
this._port = undefined
/**
* Holds the desired serial baud rate.
* @type {Number}
*/
this._baud = baud
/**
* Holds the parsing function.
* @type {!Function}
*/
this._parser = parser
/**
* Holds the current port path.
* @type {!String}
*/
this._path = undefined
/**
* Holds current state. Possible values: disconnect, open, close, disconnect_force.
* @type {String}
*/
this._state = 'close'
/**
* Logger instance. (Bunyan API).
* @type Object
*/
this._log = logger
}
/**
* Sets a new path to all future serialport instances. If a port is already open,
* it is automatically closed and a new one is opened with the new path (keeps event listeners).
* @emits data(packet): New data arrived (after being parsed by Serial#_parser).
* @emits stateChange(state): Serial#_state has changed.
* @emits error(error): An error ocurred in node-serialport.
* @return {Promise} When path is changed and the port recreated/reopened.
*/
setPath(path) {
this._log.debug('serial.setPath')
// Guard for already changed port...
if (path === this._path) {
this._log.trace('serial._path needs no change', path)
return Promise.resolve()
}
return (new Promise(resolve => {
// Any _port recreation will open this new path
this._log.trace('serial._path changed to', path)
this._path = path
// Destroy and recreate _port when necessary
if (this._port) {
this._log.trace('serial._path changed: recreating existing port')
const open = this._port.isOpen()
this._destroyPort()
.then(() => open ? this.open() : this._createPort())
.then(resolve)
} else {
resolve()
}
}))
.then(() => this.emit('pathChange', path))
}
/**
* Opens the serialport, creating it if needed.
* @emits data(packet): New data arrived (after being parsed by Serial#_parser).
* @emits stateChange(state): Serial#_state has changed.
* @emits error(error): An error ocurred in node-serialport.
* @return {Promise} Resolved when the serial port is open.
*/
open() {
this._log.debug('serial.open')
return new Promise(resolve => {
// No port? Create it!
if (!this._port) {
this._log.trace('port does not exist')
return this._createPort()
.then(() => this.open())
.then(resolve)
}
// Already open = nothing to do
if (this._port.isOpen()) {
this._log.trace('port already open')
return resolve()
}
// Open the port
this._log.trace('calling serial._port.open')
this._port.open(resolve)
})
}
/**
* Closes the serialport.
* @emits stateChange(state): Serial#_state} has changed.
* @emits error(error): An error ocurred in node-serialport.
* @return {Promise} Resolved when the serialport is closed.
*/
close() {
this._log.debug('serial.close')
// Already closed/no port = nothing to do
if (!this._port || !this._port.isOpen()) {
this._log.trace('port already closed/does not exist')
return Promise.resolve()
}
this._log.trace('calling serial._port.close')
return new Promise(resolve => this._port.close(resolve))
}
/**
* Destroys the current serialport instance. Removing all listeners and closing it beforehand.
* @protected
* @emits stateChange(state): Serial#_state has changed.
* @returns {Promise} Resolves when all is done.
*/
_destroyPort() {
this._log.debug('serial._destroyPort')
if (!this._port) {
return Promise.resolve()
}
return new Promise(resolve => {
this._port.removeAllListeners()
// Only close if necessary
if (!this._port.isOpen()) {
this._log.trace('port not open, removing it')
this._port = undefined
return resolve()
}
this._log.trace('port open, closing')
this._port.close(error => {
if (error) {
this._log.error('Error closing port!', error)
}
// Must keep going
this._port = undefined
resolve()
})
})
}
/**
* Creates the serialport instance and attaches all relevant event listeners
* that forward data and errors and keep track of state.
* @protected
* @emits data(packet): New data arrived (after being parsed by Serial#_parser).
* @emits stateChange(state): Serial#_state has changed.
* @emits error(error): An error ocurred in node-serialport.
* @return {Promise} A resolved Promise for easy chaining in {@link Serial#setPath}.
*/
_createPort() {
// Only create if it does not exist
if (this._port) {
return Promise.resolve()
}
// Create serialport instance
this._port = new SerialPort(this._path, {
baudRate: this._baud,
parser: this._parser,
autoOpen: false
})
// Register event listeners
this._port.on('data', data => this.emit('data', data))
this._port.on('error', error => {
this._log.fatal(error)
this.emit('error', error)
})
// State tracking
this._port.on('open', () => this._updateState('open'))
this._port.on('disconnect', () => this._updateState('disconnect_force'))
this._port.on('close', () => {
// Detect safe disconnections
if (this._state === 'disconnect_force') {
return this._updateState('disconnect')
}
this._updateState('close')
})
return Promise.resolve()
}
/**
* Shortcut for updating state that changes this._state and emits
* a stateChange event with one call.
* @protected
* @param {String} state New state.
* @emits stateChange(state): Serial#_state has changed.
*/
_updateState(state) {
this._state = state
this.emit('stateChange', state)
}
}
/**
* Lists available ports in the system with SerialPort.list.
* Tries to fill out vendorId and productId fields in Windows from pnpId.
* @return {Promise<Array>} Array of port information objects.
*/
export function listPorts() {
return new Promise(resolve => {
SerialPort.list((err, ports) => {
if (err) {
// TODO: reject promise with error, deal with it in Station#getAvailablePorts
return resolve([])
}
// Fill out some missing fields if possible
ports = ports.map(port => {
if ((!port.vendorId || !port.productId) && port.pnpId) {
port.vendorId = '0x' + /VID_([0-9,A-Z]*)&/.exec(port.pnpId)[1].toLowerCase()
port.productId = '0x' + /PID_([0-9,A-Z]*)&/.exec(port.pnpId)[1].toLowerCase()
}
return port
})
resolve(ports)
})
})
}
