Firmata NPM | npm.io

Firmata.js

Firmata protocol implementation for programmatic interaction with Arduino and Arduino compatible development boards.

Install

As a project dependency:

npm install firmata

For global cli use:

npm install -g firmata

REPL

If you run firmata from the command line it will prompt you for the serial port. Then it will present you with a REPL with a board variable available.

Basic Usage

Using the `"ready"` event...

With a path string:

const Firmata = require("firmata");
const board = new Firmata("system path or name");

board.on("ready", () => {
  // Arduino is ready to communicate
});

With a Serialport object:

const Serialport = require("serialport");
const Firmata = require("firmata");
const board = new Firmata(new Serialport(...));

board.on("ready", () => {
  // Arduino is ready to communicate
});

With an Etherport object:

Etherport is a TCP server that can be used with StandardFirmataEthernet or StandardFirmataWiFi when configured as a TCP client (StandardFirmataEthernet can currently only be configured as a TCP client). There is also etherport-client which is a TCP client that can be used with StandardFirmataWiFi when configured as a TCP server.

const Etherport = require("etherport");
const Firmata = require("firmata");
const board = new Firmata(new Etherport(...));

board.on("ready", () => {
  // Arduino is ready to communicate
});

Using the `readyCallback`:

const Firmata = require("firmata");
const board = new Firmata("system path or name", () => {
  // Arduino is ready to communicate
});

With a Serialport object:

const Serialport = require("serialport");
const Firmata = require("firmata");
const board = new Firmata(new Serialport(...), () => {
  // Arduino is ready to communicate
});

With an Etherport object:

const Etherport = require("etherport");
const Firmata = require("firmata");
const board = new Firmata(new Etherport(...), () => {
  // Arduino is ready to communicate
});

Any object can be a Transport object, as long as it emits an "open" event and a "data" event, which match the semantics of a Serialport object.

`Firmata`

The Firmata constructor creates an instance that represents a physical board.

new Firmata(path[, options][, readyCallback])

new Firmata(port[, options][, readyCallback])

Parameter	Type	Description	Default	Required
path	String	A system path or port name.	none	Yes*
port	Transport	A Transport object.	none	Yes*
options	object	Optional settings to used when constructing.	See Below	No
readyCallback	function	Optional "ready" callback to call when connection to board is complete.	none	No

* Either a path or a port are required.

Notes:
- new Firmata(path: string): instances can be constructed using only a system path of the serial port to open or name, for example:
  - new Firmata("/dev/usb.whatever")
  - new Firmata("/dev/ttyACM0")
  - new Firmata("COM1")
- new Firmata(port: Transport): instances can be constructed using a "Transport" object, for example:
  - new Firmata(new Serialport(...))
  - new Firmata(new Etherport(...))

Options

Property	Type	Description	Default	Required
skipCapabilities	Boolean	Set to `true` to skip the `CAPABILITY_QUERY`	`true`	No
reportVersionTimeout	Number	Time in milliseconds to wait before timing out the initial request for the firmware version.	5000	No
samplingInterval	Number	Time in milliseconds of the sampling interval on the actual board.	19	No
serialport	Object	See: Serialport:openOptions. These will be ignored if the first argument is a Transport object.	*	No

* Defaults are defined in Serialport.

Firmata Instance

board.MODES This is an enumeration of the different modes available. These are used in calls to the pinMode function.

{
  INPUT: 0x00,
  OUTPUT: 0x01,
  ANALOG: 0x02,
  PWM: 0x03,
  SERVO: 0x04,
  SHIFT: 0x05,
  I2C: 0x06,
  ONEWIRE: 0x07,
  STEPPER: 0x08,
  SERIAL: 0x0A,
  PULLUP: 0x0B,
  IGNORE: 0x7F,
  UNKOWN: 0x10
}

board.HIGH* and *board.LOW
Constants used to set a digital pin's voltage will be set to the corresponding value: 5V (or 3.3V, or 1.8V, depending on board) for HIGH, 0V (Ground) for LOW.

board.pins

This is an array of all the pins on the board.

Each value in the array is an object:

{
  mode: Number,  // Current mode of pin which is on the the board.MODES.
  value: Number, // Current value of the pin. when pin is digital and set to output it will be
                 // Firmata.HIGH or Firmata.LOW. If the pin is an analog pin it will be an numeric
                 // value between 0 and 1023.
  supportedModes: [ ...Number ], // Array of modes from board.MODES that are supported on this pin.
  analogChannel: Number, // Will be 127 for digital pins and the pin number for analog pins.
  state: Number  // For output pins this is the value of the pin on the board, for digital input
                 // it's the status of the pullup resistor (1 = pullup enabled, 0 = pullup disabled)
}

This array holds all pins digital and analog. To get the analog pin number as seen on the arduino board use the analogChannel attribute.

board.analogPins
This is an array of all the array indexes of the analog pins in the board.pins array. For example to get the analog pin 5 from the board.pins attributes use:
```
board.pins[board.analogPins[5]];`
```

Firmata Prototype API

board.pinMode(pin,mode)
Set a mode for a pin. pin is the number of the pin and the mode is on of the Firmata.MODES values. All digital pins are set to board.MODES.OUTPUT by default (because this is what the Firmata firmware running on the board defaults to) and all analog pins are set to board.MODES.ANALOG (analog input) by default.
board.digitalWrite(pin,value,enqueue)
Write an output to a digital pin. pin is the number of the pin and the value is either board.HIGH or board.LOW. enqueue is optional and when true will update the local pin value but will not write the data until flushDigitalPorts() is called.
board.flushDigitalPorts()
Directs firmata to update all ports whose values have been changed via digitalWrite with the enqueue parameter set to true.
board.digitalRead(pin,callback)
Register to get the digital value (board.HIGH or board.LOW). The value is reported via the callback whenever it changes. To get the locally stored value at any other time you can use board.pins[pinNumber].value.
Example:
```
board.digitalRead(2, function(value) {
  console.log("The value of digital pin 2 changed to: " + value);
});
```
To stop reporting digital values for a pin, call board.reportDigitalPin(digitalPinNumber, 0). To restart, call digitalRead(pin,callback) or use board.reportDigitalPin(digitalPinNumber, 1) if you don't want to call digitalRead again.
Note if you are familiar with the use of digitalRead when writing an Arduino sketch, the firmata.js implementation of digitalRead is very different in that it's reporting-based rather than immediately returning a value as in an Arduino sketch.
board.analogWrite(pin,value)
Write an output to an analog pin (PWM). pin is the number of the pin and the value is between 0 and 255.
board.analogRead(pin,callback)
Register to get the analog value (0 - 1023) of the pin. The value is reported via the callback at the current sampling interval. The sampling interval is 19 milliseconds by default so the analog value is reported every 19 ms unless the sampling interval is changed. See documentation for board.setSamplingInterval below. To get the locally stored value at any other time you can use board.pins[board.analogPins[analogPinNumber]].value, but the value will only be as fresh as the most recent report via the sampling interval.
Example:
```
board.analogRead(0, function(value) {
  console.log("The value of pin A0 is " + value + " as reported at the sampling interval");
});
```
To stop reporting analog values for a pin, call board.reportAnalogPin(analogPinNumber, 0). To restart, call analogRead(pin,callback) or use board.reportAnalogPin(analogPinNumber, 1) if you don't want to call analogRead again.
Note if you are familiar with the use of analogRead when writing an Arduino sketch, the firmata.js implementation of analogRead is very different in that it's reporting-based rather than immediately returning a value as in an Arduino sketch.
board.setSamplingInterval(interval)
Set the sampling interval in milliseconds. Default is 19 ms. Minimum is 10 ms, max is 65535 ms. The sampling interval controls how often analog values are reported when using board.analogRead and how often i2c device values are reported when using board.i2cRead. The same sampling interval is used for both analog and i2c value reporting.
You can alternatively set the sampling interval when creating a new Firmata instance:
```
// set sampling interval to 30 milliseconds
const board = new Firmata(serialPortName, {samplingInterval: 30});
```

board.getSamplingInterval()
Get the current sampling interval value in milliseconds.

Servo

board.servoWrite(pin, degree)
board.servoWrite(pin, pulse)
Write a degree value to a servo pin.
board.servoConfig(pin, min, max)
Setup a servo with a specific min and max pulse (call instead of pinMode, which will provide default).

I2C

board.i2cConfig(delay)
Configure and enable I2C, optionally provide a value in μs to delay between reads (defaults to 0). Required to enable I2C communication.

board.i2cConfig(options)

Configure and enable I2C, optionally provide an object that contains properties to use for whose value is a number in μs to delay between reads. Required to enable I2C communication.

Option	Description	Default	Required?
delay	µS delay between setting a register and requesting bytes from the register	0	No
address	Valid I2C address, used when there are specific configurations for a given address	none	No
settings	An object of properties to associate with a given address.	none	No

Setting	Description	Default	Required?
stopTX	Stop transmission after setting a register to read from. Setting to `false` will keep the transmission connection active. An example of the `false` behavior is the MMA8452	true	No

board.i2cWrite(address, [...bytes])
Write an arbitrary number of bytes. May not exceed 64 Bytes.
- board.i2cWrite(address, byte)
Write a single byte to the current register.
board.i2cWrite(address, register, [...bytes])
Write an arbitrary number of bytes to the specified register. May not exceed 64 Bytes.
board.i2cWrite(address, register, byte)
Write a single byte to the specified register.
board.i2cWriteReg(address, register, byte)
Write a byte value to a specific register.
board.i2cRead(address, numberOfBytesToRead, handler(data))
Read a specified number of bytes, continuously. handler receives an array of values, with a length corresponding to the number of read bytes.
board.i2cRead(address, register, numberOfBytesToRead, handler(data))
Read a specified number of bytes from a register, continuously. handler receives an array of values, with a length corresponding to the number of read bytes.
board.i2cReadOnce(address, numberOfBytesToRead, handler(data))
Read a specified number of bytes, one time. handler receives an array of values, with a length corresponding to the number of read bytes.
board.i2cReadOnce(address, register, numberOfBytesToRead, handler(data))
Read a specified number of bytes from a register, one time. handler receives an array of values, with a length corresponding to the number of read bytes.
board.sendI2CConfig(delay) Deprecated
Set I2C Config on the arduino
board.sendI2CWriteRequest(slaveAddress, [bytes]) Deprecated
Write an array of bytes to a an I2C device.
board.sendI2CReadRequest(slaveAddress, numBytes, function(data)) Deprecated
Requests a number of bytes from a slave I2C device. When the bytes are received from the I2C device the callback is called with the byte array.

Debug

board.sendString("a string")
Send an arbitrary string.

One-Wire

board.sendOneWireConfig(pin, enableParasiticPower)
Configure the pin as the controller in a 1-wire bus. Set enableParasiticPower to true if you want the data pin to power the bus.
board.sendOneWireSearch(pin, callback)
Searches for 1-wire devices on the bus. The callback should accept an error argument and an array of device identifiers.
board.sendOneWireAlarmsSearch(pin, callback)
Searches for 1-wire devices on the bus in an alarmed state. The callback should accept and error argument and an array of device identifiers.
board.sendOneWireRead(pin, device, numBytesToRead, callback)
Reads data from a device on the bus and invokes the callback.
board.sendOneWireReset()
Resets all devices on the bus.
board.sendOneWireWrite(pin, device, data)
Writes data to the bus to be received by the device. The device should be obtained from a previous call to sendOneWireSearch.
board.sendOneWireDelay(pin, delay)
Tells Firmata to not do anything for the amount of ms. Use when you need to give a device attached to the bus time to do a calculation.
board.sendOneWireWriteAndRead(pin, device, data, numBytesToRead, callback)
Sends the data to the device on the bus, reads the specified number of bytes and invokes the callback.

Serial

board.SERIAL_PORT_IDs

IDs for both hardware and software serial ports on the board.

{
  HW_SERIAL0: 0x00,
  HW_SERIAL1: 0x01,
  HW_SERIAL2: 0x02,
  HW_SERIAL3: 0x03,
  SW_SERIAL0: 0x08,
  SW_SERIAL1: 0x09,
  SW_SERIAL2: 0x10,
  SW_SERIAL3: 0x11,
}

board.serialConfig(options)

Configure a hardware or serial port -- required before using serial read/write functions

{
  portId: board.SERIAL_PORT_IDs.HW_SERIAL1, // <number> The serial port to use (HW_SERIAL2, SW_SERIAL0, SW_SERIAL1...)
  baud:   115200, // <number> (optional) The baud rate of the serial port; default is 57600
  rxPin:  5,      // <number> (optional)[SW Serial only] The RX pin of the SoftwareSerial instance
  txPin:  6       // <number> (optional)[SW Serial only] The TX pin of the SoftwareSerial instance
}

board.serialWrite(portId, inBytes)
Write an array of bytes to the specified serial port.

board.serialRead(portId, callback)
board.serialRead(portId, maxBytesToRead, callback)
Start continuous reading of the specified serial port. The port is checked for data each iteration of the main Arduino loop.

maxBytesToRead specifies the maximum number of bytes to read per iteration. If there are less bytes in the buffer, the lesser number of bytes will be returned. A value of 0 indicates that all available bytes in the buffer should be read.

board.serialStop(portId)
Stop continuous reading of the specified serial port. This does not close the port, it stops reading it but keeps the port open.
board.serialClose(portId)
Close the specified serial port.
board.serialFlush(portId)
Flush the specified serial port. For hardware serial, this waits for the transmission of outgoing serial data to complete. For software serial, this removes any buffered incoming serial data.
board.serialListen(portId)
For SoftwareSerial only. Only a single SoftwareSerial instance can read data at a time. Call this method to set this port to be the reading port in the case there are multiple SoftwareSerial instances.

AccelStepperFirmata

AccelStepperFirmata in configurableFirmata wraps Mike McCauley’s AccelStepper library. Accelstepper gives basic acceleration for individual steppers and support for multiSteppers. multiSteppers allow you to coordinate the movements of a group of steppers so that they arrive at their desired positions simultaneously.

Requests for stepper movements are made asyncrhonously and movements can be interrupted with a call to stop or by setting a new target position with accelStepperTo or accelStepperMove.

accelStepper support 2, 3, and 4 wire configurations as well as step + direction controllers like the easyDriver.

board.STEPPER.TYPE

Available Stepper or controller types.

{
  DRIVER: 1,
  TWO_WIRE: 2,
  THREE_WIRE: 3,
  FOUR_WIRE: 4,
}

board.STEPPER.STEP_SIZE
Available step sizes.
```
{
  WHOLE: 0,
  HALF: 1
}
```

board.STEPPER.DIRECTION

Stepper directions.

{
  CCW: 0,
  CW: 1
}

board.accelStepperConfig(options)

Configure a stepper motor

{
  deviceNum: 0, // <number> Device number for the stepper (range 0-9)
  type: board.STEPPER.TYPE.DRIVER, // <number> (optional) Type of stepper or controller; default is FOUR_WIRE
  stepSize: board.STEPPER.STEP_SIZE.HALF, // <number> (optional) Size of step; default is WHOLE
  stepPin: 2, // <number> (required if type === DRIVER) The step pin for a step+direction stepper driver
  directionPin: 3, // <number> (required if type === DRIVER) The direction pin for a step+direction stepper driver
  motorPin1: 2, // <number> (required if type !== DRIVER) Motor control pin 1
  motorPin2: 3, // <number> (required if type !== DRIVER) Motor control pin 2
  motorPin3: 4, // <number> (required if type === THREE_WIRE or FOUR_WIRE) Motor control pin 3
  motorPin4: 5, // <number> (required if type === FOUR_WIRE) Motor control pin 4
  enablePin: 6, // <number> (optional) Enable pin for motor controller pin
  invertPins: 0 // <number> (optional) Controls which pins to invert (see table below); default is 0
}

invertPins

The invertPins value is a 5-bit number

bit 5	bit 4	bit 3	bit 2	bit 1
invert motorPin1	invert motorPin2	invert motorPin3	invert motorPin4	invert enablePin

Examples:

Invert motor pins 1, 2, 3 & 4 = 0b11110 = 30
Invert motor pins 1, 2 & enablePin = 0b11001 = 25

board.accelStepperZero(deviceNum)
Set the current stepper position to zero
board.accelStepperStep(deviceNum, steps, callback)
Move the stepper motor by a number of steps. Optional callback will be called when motor has finished moving or stop is called
board.accelStepperTo(deviceNum, position, callback)
Move the stepper motor to a specified position. Optional callback will be called when motor has finished moving or stop is called
board.accelStepperEnable(deviceNum, enabled)
If enabled param is set to false, stepper will be disabled, otherwise stepper will be enabled
board.accelStepperStop(deviceNum)
Stop the stepper motor. Triggers a stepper-done event
board.accelStepperReportPosition(deviceNum)
Request the current position of the stepper. Triggers a "stepper-position" event.
board.accelStepperSpeed(deviceNum, speed)
Set the speed of the stepper in steps per second
board.accelStepperAcceleration(deviceNum, acceleration)
Set the acceleration and deceleration for the stepper in steps / sec^2
board.multiStepperConfig(opts)
Configure a multStepper group. multiStepper groups allow you to pass an array of targeted positions and have all the steppers move to their targets and arrive at the same time. Note that acceleration cannot be used when moving a multiStepper group.
```
opts = {
  groupNum: 0, // <number> Group number for the stepper group (range 0-4)
  devices: board.STEPPER.TYPE.DRIVER // [<number>] Array of deviceNum's used in group
}
```
board.multiStepperTo(groupNum, positions, callback)
Move a goup of steppers to and array of desired positions. Optional callback will be called when group has finished moving or multiStepperStop is called
board.multiStepperStop(groupNum)
Stop a group of stepper motors. Triggers a multi-stepper-done event

Sysex

board.sysexResponse(commandByte, handler)
Allow user code to handle arbitrary sysex responses. commandByte must be associated with some message that's expected from the slave device. The handler is called with an array of raw data from the slave. Data decoding must be done within the handler itself.
- Use Firmata.decode(data) to extract useful values from the incoming response data.
board.sysexCommand(message)
Allow user code to send arbitrary sysex messages. The message array is expected to be all necessary bytes between START_SYSEX and END_SYSEX (non-inclusive). It will be assumed that the data in the message array is already encoded as 2 7-bit bytes LSB first.
- Use Firmata.encode(data) to encode data values into an array of 7-bit byte pairs.
board.clearSysexResponse(commandByte)
Allow user to remove sysex response handler such as one previously set through board.sysexResponse(commandByte, handler).

Encode/Decode

Firmata.encode(data)
Encode an array of 8-bit data values as an array of two 7-bit byte pairs (each). (LSB first).
Firmata.decode(data)
Decode an array of 7-bit byte pairs into a an array of 8-bit data values. (LSB first)

License

(The MIT License)

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.

firmata-io serialport