Nextion serial client

Lightweight Python 3.8+ async library to control Nextion displays.

Installation

Pypi

pip3 install nextion

Simple usage:

import asyncio
import logging
import random

from nextion import Nextion, EventType

class App:
    def __init__(self):
        self.client = Nextion('/dev/ttyS1', 9600, self.event_handler)

    # Note: async event_handler can be used only in versions 1.8.0+ (versions 1.8.0+ supports both sync and async versions)
    async def event_handler(self, type_, data):
        if type_ == EventType.STARTUP:
            print('We have booted up!')
        elif type_ == EventType.TOUCH:
            print('A button (id: %d) was touched on page %d' % (data.component_id, data.page_id))

        logging.info('Event %s data: %s', type, str(data))

        print(await self.client.get('field1.txt'))

    async def run(self):
        await self.client.connect()

        # await client.sleep()
        # await client.wakeup()

        # await client.command('sendxy=0')

        print(await self.client.get('sleep'))
        print(await self.client.get('field1.txt'))

        await self.client.set('field1.txt', "%.1f" % (random.randint(0, 1000) / 10))
        await self.client.set('field2.txt', "%.1f" % (random.randint(0, 1000) / 10))

        await self.client.set('field3.txt', random.randint(0, 100))

        print('finished')

if __name__ == '__main__':
    logging.basicConfig(
        format='%(asctime)s - %(levelname)s - %(message)s',
        level=logging.DEBUG,
        handlers=[
            logging.StreamHandler()
        ])
    loop = asyncio.get_event_loop()
    app = App()
    asyncio.ensure_future(app.run())
    loop.run_forever()

Nextion constructor parameters

url: str # serial dev
baudrate: int # baud rate
event_handler: typing.Callable[[EventType, any], None] # Event handler function
loop=asyncio.get_event_loop() # your own event loop
reconnect_attempts: int = 3 # how many times to try to retry command in case of failure
encoding: str = 'ascii' # Nextion encoding

Nextion parameters

Encoding

You can update encoding on fly (This changes encoding of serial communication only):

client.encoding = 'latin-1'

Get current set encoding (Not fetched from the device)

print(client.encoding)

Event handling

event_handler method in the example above will be called on every event coming from the display.

For some components in the Nextion Editor you need to check Send Component ID for required event.

Firmware uploading

If you installed the library you should have nextion-fw-upload command in your PATH.

nextion-fw-upload -h

Otherwise use next command in the root of the project:

python -m nextion.console_scripts.upload_firmware -h

Usage (check with option -h)

usage: nextion-fw-upload [-h]
                         [-b {2400,4800,9600,19200,38400,57600,115200,230400}]
                         [-ub {2400,4800,9600,19200,38400,57600,115200,230400}]
                         [-v]
                         device file

positional arguments:
  device                device serial port
  file                  firmware file *.tft

optional arguments:
  -h, --help            show this help message and exit
  -b {2400,4800,9600,19200,38400,57600,115200,230400}, --baud {2400,4800,9600,19200,38400,57600,115200,230400}
                        baud rate
  -ub {2400,4800,9600,19200,38400,57600,115200,230400}, --upload_baud {2400,4800,9600,19200,38400,57600,115200,230400}
                        upload baud rate
  -v, --verbose         output debug messages

Additional resources:

• https://nextion.tech/instruction-set/
• PyPI