pigpio-client

Pigpio-client exposes the socket interface APIs of the pigpio library using nodejs. This allows you to connect to a Raspberry Pi, running remotely or local, and manipulate its GPIO pins with javascript. The pigpio socket interface is described more fully here:

New in v1.5.2

• Add Trigger API

Installing and Running pigpio daemon

A guide for installing and running pigpiod along with other useful information can be found in the wiki

pigpio-client usage example

const pigpio = require('pigpio-client').pigpio({host: 'raspberryHostIP'});  

const ready = new Promise((resolve, reject) => {
  pigpio.once('connected', resolve);
  pigpio.once('error', reject);
});

function wait(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

ready.then(async (info) => {
  // display information on pigpio and connection status
  console.log(JSON.stringify(info,null,2));

  // get events from a button on GPIO 17
  const button = pigpio.gpio(17);
  await button.modeSet('input');
  button.notify((level, tick)=> {
    console.log(`Button changed to ${level} at ${tick} usec`)
  });

  // control an LED on GPIO 4
  const led = pigpio.gpio(4);
  await led.modeSet('output');
  await led.write(1);  // turn on LED
  await wait(500);
  await led.write(0);  // turn off
  await wait(500);

  // use waves to blink the LED rapidly (toggle every 100ms)
  await led.waveClear();
  await led.waveAddPulse([[1, 0, 100000], [0, 1, 100000]]);
  const blinkWave = await led.waveCreate();
  led.waveChainTx([{loop: true}, {waves: [blinkWave]}, {repeat: true}]);

  // wait for 10 sec, stop the waves
  await wait(10000);
  await led.waveTxStop();
}).catch(console.error);

All APIs accept error-first callback as an optional last argument, and also return a promise (and thus can be safely used with async/await). Depending on the presence of a callback argument, errors returned by pigpio are delivered in two ways: Methods called without a callback emit 'error' events. Methods called with a callback are supplied an Error object as the first argument returned.
Arguments to callback are: (error, response) unless otherwise noted.

Constructors

PigpioClient.pigpio(options): Construct a pigpio object and connect it to options.host.

Options have the following properties:

• host: The remote IP address to host running pigpio daemon. Defaults to 'localhost'.
• port: The port used to configure pigpiod. Default is 8888.
• pipelining: DEPRECATED. Configures internal socket communications.
• timeout: The network socket timeout in minutes. Default is 0. Timeout enables automatic retries to connect to the server after any socket error is encountered. During the timeout period, connection will be retried every 5 seconds. An 'error' event will be emitted after the timeout period expires. After connection is established, if keep-alive packets are not received from the server within timeout minutes, the network sockets will be closed and a 'disconnected' event emitted. If timeout is used, it is recommended to set its value to > 1 minute. Also recommended is to use V68 of pigpio library.

pigpio.gpio(gpio_pin) Return a gpio object set to the Broadcom GPIO number specified by gpio_pin. An error will be thrown if gpio_pin is not a valid user GPIO.

pigpio.serialport(rx,tx,dtr) Return a serialport object constructed from GPIO pins for rx, tx and dtr. Rx and Tx may use the same pin for a loop-back. DTR pin is optional. An error will be thrown if the pins are not valid user GPIO. Constructing a serialport object will clear all waveforms.

Events

'connected' Emitted after both command and notification sockets are connected to pigpiod. An 'info' object is passed to the handler. You should wait for this event before attempting to construct other objects - gpio, serialport.

'disconnected' Emitted when the socket connections are closed, for any reason, or when no pigpio keep-alive packet is received within timeout>0 minutes.

'error' Error objects are passed to the 'error' event handler unless a callback was provided when invoking an API. Pigpio errors have the name property set to PigpioError and a code and message property set corresponding the numeric value returned by the socket interface. For pigpio-client specific APIs, the error name is set to PigpioClientError.

Methods

Note: Unless otherwise stated, all references to gpio pin numbers use Broadcom numbering.

pigpio methods

pigpio.getInfo(cb) Returns useful information about rpi hardware and pigpiod.

pigpio.getCurrentTick(cb) Return current timer tick in microseconds. gpioTick

pigpio.readBank1(cb) Returns levels of GPIO bits 31-0. gpioRead_Bits_0_31

pigpio.end(cb) Ends socket communications. Callback is invoked on 'disconnected' event.

pigpio.destroy() DEPRECATED. Invokes socket.destroy() on both network sockets.

pigpio.connect() Re-establishes communication with server after being disconnected.

pigpio.i2cOpen(bus, address, callback) Return a handle for communication with a device attached to a bus on the I2C peripheral. bus==0 uses (Broadcom) gpio 0 and 1, while bus==1 use gpio 2 and 3 for SDA and SCL respectively. address takes values 1-127.

pigpio.i2cClose(handle, callback) Close the I2C device associated with handle.

pigpio.i2cReadDevice(handle, count, callback) Read count bytes from the i2c device referred by handle. Returns tuple (error, count, data). error is 0 on success or an error code. count is the number of bytes read. data is a buffer.

pigpio.i2cWriteDevice(handle, data, callback) Write data to the i2c device referred by handle. data is a byte array or utf8 string. Returns 0 if OK, otherwise an error code.

pigpio.bscI2C(address, data, callback) Transfer data to/from the BSC I2C slave peripheral using gpio 18 (SDA) and 19 (SCL). The data bytes (if any) are written to the BSC transmit FIFO and the bytes in the BSC receive FIFO are returned. The depth of the FIFO is 32 bytes.

This function is not available on the BCM2711 (e.g. as used in the Pi4B).

address is a non-zero 7-bit i2c address the slave device will respond to.
If address is 0, the BSC peripheral is turned off and gpio 18/19 are reset to input mode.

data, optional, is a byte array or utf8 string up to 512 bytes.

The return value is a byte array containing: A byte-count byte followed by 4 status bytes followed by the data bytes read from the RX FIFO.

The EVENT_BSC event is emitted when data is available to read from the BSC I2C device.

gpio basic methods

gpio.modeSet(mode, cb) Sets the gpio mode to be input or output. The mode argument must be string with a value of 'input', 'in', 'output' or 'out'. The optional callback is invoked with either null argument on success or error on failure.

gpio.trigger(len, level, cb) Send a trigger pulse to a GPIO. The GPIO is set to level for len microseconds. The optional callback is invoked with either null argument on success or error on failure.

gpio.modeGet(cb) Returns the mode of gpio as argument to callback. gpioGetMode

gpio.pullUpDown(pud, cb) pud=2: set pullup resistor, pud=1: set pulldown resistor, pud=0: clear resistor setting.gpioSetPullUpDown

gpio.read(cb) Returns the gpio pin level as argument to callback.

gpio.write(level, cb) Sets the gpio output level to on (1) or off (0). If PWM or servo pulses are active on the gpio they are switched off. gpioWrite

gpio.analogWrite(dutyCycle, cb) Set the PWM dutycycle (0-255) on the gpio. Caution: This will stop all waveform generation. gpioPWM.

gpio.hardwarePWM(frequency, dutyCycle, callback) Set the hardware PWM dutycycle (0-1000000) on the gpio. Only works with pins that support hardware PWM (12,13,18,19); max two channels available. PWM frequency is also specified - not likely to work above 30MHz though. Caution: This will stop all waveform generation. gpioHardwarePWM.

gpio.setServoPulsewidth(pulseWidth, cb) Starts servo pulses on gpio. Pulsewidth can be set to 0 (off) and from 500 (most anti-clockwise) to 2500 (most clockwise). Be aware that you can damage your servo when setting a too high pulseWidth. A value of 1500 (mid-point) is a good starting point to check range of your servo. gpioServo

gpio.getServoPulsewidth(cb) Returns the pulsewidth of gpio as argument to callback. gpioGetServoPulsewidth

gpio waveform methods

gpio.waveClear(cb) Clear all waveforms (release DMA control blocks, reset wave IDs). gpioWaveClear

gpio.waveCreate(cb) Returns the wave id of waveform created from previous calls to waveAddPulse or waveAddSerial. gpioWaveCreate

gpio.waveBusy(cb) Returns 1 if wave is still transmitting, otherwise 0. gpioWaveTxBusy

gpio.waveNotBusy(interval, callback) Invokes callback when waveform ends. Polls waveform status at interval msec. Defaults to 25msec.

gpio.waveAddPulse([Pulse_t], cb) Add array of Pulse_t to gpio of current waveform. Pulse_t is a tuple [1, 0, delay] for positive pulse, [0, 1, delay] for negative pulse width = delay. gpioWaveAddGeneric.

gpio.waveChainTx([{loop:x}, {waves: [wids]}, {delay:y}, {repeat:z}], cb) gpioWaveChain
Transmit a chain of waves represented by array of wave IDs [wids]. The chain can have loops, be separated by delays and repeated by inclusion of option objects.

• loop : x, begins a loop. x can be anything
• delay: y, insert of delay of y=0 to 65535 microseconds
• repeat: z, repeat loop z=0 to 65535 times or forever if z=true

gpio.waveSendSync(wid, cb) Synchronizes wid to the currently active waveform. gpioWaveTxSend with mode set to PI_WAVE_MODE_ONE_SHOT_SYNC.

gpio.waveSendOnce(wid, cb) Send the wave id, wid, one time. gpioWaveTxSend with mode set to PI_WAVE_MODE_ONE_SHOT.

gpio.waveTxAt(cb) Return currently active wave id, no wave being transmitted (9999) or wave not found (9998). gpioWaveTxAt

gpio.waveTxStop(cb) Aborts the transmission of the current waveform. This function is intended to stop a waveform started in repeat mode. waveTxStop

gpio.waveDelete(wid, cb) Delete the wave id wid. gpioWaveDelete

Note: waveClear, waveCreate and waveBusy are not gpio specific. These methods are made available to the gpio object for convenience and as a reminder that only a single waveform can be active.
Note: waveBusy and waveNotBusy return status are global indication of waveform state - not specific to gpio!

gpio notification methods

gpio.notify(callback) Registers the notification function callback. callback is invoked whenever the gpio state changes. Arguments to callback are level and tick where tick represents the system's time since boot.

gpio.endNotify(cb) Unregisters the notification on gpio. For convenience, a null tick value is sent - useful for stream objects that wrap the notifier callback.

gpio.glitchSet(steady, cb) Sets a glitch filter (0-300000) on gpio in microseconds. Only effects notifications. gpioGlitchFilter

gpio bit_bang_serial methods

gpio.serialReadOpen(baudRate, dataBits, cb) - gpioSerialReadOpen

gpio.serialRead(count, cb) Returns cb(null, length, buf). buf is Uint8Array of length length. gpioSerialRead

gpio.serialReadClose(cb) gpioSerialReadClose

gpio.serialReadInvert(mode, cb) Mode is 'invert' || 'normal'. gpioSerialReadInvert

waveAddSerial(baud,bits,delay,data,cb) - gpioWaveAddSerial

serialport methods

Experimental, these APIs may change in the future.

serialport.open(baudrate,databits,cb) Argument baudRate must be a number from 50 to 250000. Argument dataBits must be a number from 1 to 32. If the rx gpio is already open for bit-bang serial read the method will close the gpio and then re-open it.

serialport.read(size, cb) size is an optional argument representing the number of bytes to read. If not specified, all the data in pigpio's cyclic buffer is returned (up to 8192 bytes). Returns cb(null, data) where data is a utf8 string. If the serialport is not open, returns cb(null).

serialport.write(data) data is utf8 string or Uint8Buffer. The data is buffered then sent out in chunk sizes that fit the available waveform resources. Returns the number of bytes remaining in the buffer. If the serialport is not open, returns -1. Any pigpio errors occurring during write will be thrown to limit the possibility of data corruption.

serialport.close(cb) Close serialport.

serialport.end(cb) Closes rx gpio for bb_serial_read and changes gpios tx and dtr mode to input.

Environment Variables for Debugging

Environment variables can be set to display messages from pigpio-client to assist in troubleshooting your application. DEBUG='pigpio' will enable status messages. For tracing the all socket communication use: PIGPIO=1.

DEBUG='pigpio' node myApp.js

Issues/Requests/Questions

https://github.com/guymcswain/pigpio-client/issues

Limitations

Only a single instance of serialport is supported. <=1.1.x