nextion

Communicate with ITEAD's Nextion HMI Devices

Status

• Support return data
• Support operation commands
• Reasonable, high-level API; don't require user to send raw commands
  • System-level abstraction
  • Component-level abstraction
• Tessel 2 support
• Remove serialport dependency

Basic Usage

COM Port, USB-to-UART adapter, etc.

const Nextion = require('nextion');

// CH340G usually shows up at this path on macOS
Nextion.fromPort('/dev/tty.SLAB_USBtoUART')
  .then(nextion => {
    console.log('Listening...');

    nextion.on('touchEvent', data => {
      console.log(data);
    });
  });

For port auto-detection, try:

const Nextion = require('nextion');

Nextion.create()
  .then(nextion => {
    // do exciting stuff here
  });

Tessel 2

const tessel = require('tessel');
const Nextion = require('nextion/minimal');

const uart = new tessel.port.A.UART({
  baudrate: 9600
});

Nextion.fromSerial(uart)
  .then(nextion => {
    // Yipper McCheese!
  });

The nextion/minimal module is for resource-constrained systems; it's compressed and does not include source maps.

Compatibility

As long as the argument passed into Nextion.fromSerial is a Duplex stream or a duck-typed one (a la serialport), you should be able to use it. Hack away!

API docs

Events

The Nextion instance (nextion) in above examples is an EventEmitter. If the device sends any of these over the UART channel, the Nextion instance will emit a corresponding event (w/ data, if any).

• Events (Table 2)
  • 0x65 - touchEvent: Touch event return data
  • 0x66 - pageId: Current page ID
  • 0x67 - touchCoordinate: Touch coordinate data
  • 0x68 - touchCoordinateOnWake: Touch coordinate data (on wake)
  • 0x70 - stringData: String variable data
  • 0x71 - numericData: Numeric variable data
  • 0x86 - autoSleep: Device automatically enters sleep mode
  • 0x87 - autoWake: Device automatically wakes from sleep mode
  • 0x88 - startup: Successful system startup
  • 0x89 - cardUpgrade: Start SD card upgrade
  • 0xfd - transmitFinished: Data transmit finished
  • 0xfe - transmitReady: Ready to receive data transmission

TODO: Describe shape of data for data-emitting events.

Motivation

• Send & receive events over UART to a Nextion device (hardware reference)
• Support Tessel 2
• Support USB-to-UART serial adapters for debugging
• Endgame: combine a Tessel 2 w/ a Nextion to design/implement a (mainly) JS-based home environmental control panel/dashboard.

Future:

• Ensure support on popular ARMv6/7/8
• Ensure support on popular (non-Tessel) MIPS devices
• Interface into GUI designer commands

Development

• Use environment variable DEBUG=nextion* for debug output.
• To run end-to-end tests against a connected device, read test/e2e/README.md, then execute yarn test:e2e.
• For serial port debugging, use DEBUG=nextion*,serialport.

Notes

ARM

If the serialport module supports the architecture, this module should work out-of-the-box, meaning RPi's and BBB's are theoretically covered.

MIPS

This shouldn't be too bad, because the Tessel 2 is MIPS-based, but we require Node.js v4. Other MIPS-based boards I've used have had trouble getting it compiled, packaged, or running at a respectable speed.

License

©️ 2017 Christopher Hiller. Licensed MIT.