pigpio-client/readme.md

A nodejs client for pigpio socket interface.

# 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:](http://abyz.me.uk/rpi/pigpio/sif.html)

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](https://github.com/guymcswain/pigpio-client/wiki/Install-and-configure-pigpiod)

### pigpio-client usage example
```javascript
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: <string> The remote IP address to host running pigpio daemon.  Defaults 
to 'localhost'.
- port: <number> The port used to configure pigpiod.  Default is 8888.
- pipelining: <boolean> DEPRECATED. Configures internal socket communications.
- timeout: <number> 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`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioTick)   

**`pigpio.readBank1(cb)`**  Returns levels of GPIO bits 31-0.  [`gpioRead_Bits_0_31`](http://abyz.me.uk/rpi/pigpio/cif.html#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`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioGetMode)  

**`gpio.pullUpDown(pud, cb)`**  pud=2: set pullup resistor, pud=1: set pulldown
resistor, pud=0: clear resistor setting.[`gpioSetPullUpDown`](http://abyz.me.uk/rpi/pigpio/cif.html#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`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWrite)  

**`gpio.analogWrite(dutyCycle, cb)`**  Set the PWM dutycycle (0-255) on the gpio.  Caution: 
This will stop all waveform generation. [`gpioPWM`](http://abyz.me.uk/rpi/pigpio/cif.html#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`](http://abyz.me.uk/rpi/pigpio/cif.html#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`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioServo)  

**`gpio.getServoPulsewidth(cb)`** Returns the pulsewidth of gpio as argument to callback. [`gpioGetServoPulsewidth`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioGetServoPulsewidth)  

### gpio waveform methods
**`gpio.waveClear(cb)`** Clear all waveforms (release DMA control blocks, reset wave IDs). [`gpioWaveClear`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveClear)  

**`gpio.waveCreate(cb)`** Returns the wave id of waveform created from previous calls 
to `waveAddPulse` or `waveAddSerial`.  [`gpioWaveCreate`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveCreate)    

**`gpio.waveBusy(cb)`**  Returns 1 if wave is still transmitting, otherwise 0. [`gpioWaveTxBusy`](http://abyz.me.uk/rpi/pigpio/cif.html#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`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveAddGeneric).  

**`gpio.waveChainTx([{loop:x}, {waves: [wids]}, {delay:y}, {repeat:z}], cb)`**
[`gpioWaveChain`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveChain)   
Transmit a chain of waves represented by array of wave IDs `[wids]`.  The chain can have **loop**s, be separated by **delay**s and **repeat**ed 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.](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveTxSend)    

**`gpio.waveSendOnce(wid, cb)`**  Send the wave id, `wid`, one time. [`gpioWaveTxSend` with mode set to PI_WAVE_MODE_ONE_SHOT.](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveTxSend)  

**`gpio.waveTxAt(cb)`**  Return currently active wave id, no wave being transmitted 
(9999) or wave not found (9998). [`gpioWaveTxAt`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveTxAt)  

**`gpio.waveTxStop(cb)`**  Aborts the transmission of the current waveform.
This function is intended to stop a waveform started in repeat mode. [`waveTxStop`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveTxStop)  

**`gpio.waveDelete(wid, cb)`**  Delete the wave id `wid`. [`gpioWaveDelete`](http://abyz.me.uk/rpi/pigpio/cif.html#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`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioGlitchFilter)  

### gpio bit\_bang\_serial methods  
**`gpio.serialReadOpen(baudRate, dataBits, cb)`** - [`gpioSerialReadOpen`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioSerialReadOpen)   

**`gpio.serialRead(count, cb)`**  Returns cb(null, length, buf). *buf* is Uint8Array
of length *length*. [`gpioSerialRead`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioSerialRead)  

**`gpio.serialReadClose(cb)`**  <add text>[`gpioSerialReadClose`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioSerialReadClose)  

**`gpio.serialReadInvert(mode, cb)`**  Mode is 'invert' || 'normal'. [`gpioSerialReadInvert`](http://abyz.me.uk/rpi/pigpio/cif.html#gpioSerialReadInvert)  

**`waveAddSerial(baud,bits,delay,data,cb)`**  - [`gpioWaveAddSerial`](http://abyz.me.uk/rpi/pigpio/cif.html#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**