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.

EventType	Data	Data attributes
TOUCH	TouchDataPayload	page_id, component_id, touch_event
TOUCH_COORDINATE	TouchCoordinateDataPayload	x, y, touch_event
TOUCH_IN_SLEEP	TouchCoordinateDataPayload	x, y, touch_event
AUTO_SLEEP	None	-
AUTO_WAKE	None	-
STARTUP	None	-
SD_CARD_UPGRADE	None	-

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