Nextion TFT LCD Display

The nextion display platform allows you to use Nextion LCD displays (datasheet, iTead) with ESPHome.

../../_images/nextion-full.jpg

Nextion LCD Display.

As the communication with the Nextion LCD display is done using UART, you need to have an UART bus in your configuration with rx_pin both the tx_pin set to the respective pins on the display. The Nextion uses a baud rate of 9600 by default. It may be configured to use a faster speed by adding (for example)

baud=115200   // Sets the baud rate to 115200
bkcmd=0       // Tells the Nextion to not send responses on commands. This is the current default but can be set just in case

to the program.s source file (in the Nextion Editor) before the page line. This permits faster communication with the Nextion display and it is highly recommended when using Hardware UARTs. Without a hardware uart make sure to set the baud rate to 9600.

The below example configures a UART for the Nextion display to use

# Example configuration entry
display:
  - platform: nextion
    id: nextion1
    lambda: |-
      it.set_component_value("gauge", 50);
      it.set_component_text("textview", "Hello World!");

Configuration variables:

  • uart_id (Optional, ID): The ID of the UART bus you wish to use for this display. Use this if you want to use multiple UART buses at once.

  • brightness (Optional, percentage): Set display brightness in %. Defaults to 100%

  • lambda (Optional, lambda): The lambda to use for rendering the content on the nextion display. See Rendering Lambda for more information. This is typically empty. The individual components for the Nextion will handle almost all features needed for updating

  • update_interval (Optional, Time): The interval to call the lambda to update the display. Defaults to 5s.

  • id (Optional, ID): Manually specify the ID used for code generation.

  • tft_url (Optional, string): The URL to download the TFT file from for updates. See Nextion Upload.

  • touch_sleep_timeout (Optional, int): Sets internal No-touch-then-sleep timer in seconds.

  • start_up_page (Optional, int): Sets the page to display when ESPHome connects to the Nextion. (Nextion shows page 0 on start-up by default).

  • wake_up_page (Optional, int): Sets the page to display after waking up

  • auto_wake_on_touch (Optional, boolean): Sets if Nextion should auto-wake from sleep when touch press occurs.

  • exit_reparse_on_start (Optional, boolean): Request the Nextion exit Active Reparse Mode before setup of the display. Defaults to false.

  • skip_connection_handshake (Optional, boolean): Sets whether the initial display connection handshake process is skipped. When set to true, the connection will be established without performing the handshake. This can be useful when using Nextion Simulator. Defaults to false.

  • on_setup (Optional, Action): An action to be performed after ESPHome connects to the Nextion. See Nextion Automation.

  • on_sleep (Optional, Action): An action to be performed when the Nextion goes to sleep. See Nextion Automation.

  • on_wake (Optional, Action): An action to be performed when the Nextion wakes up. See Nextion Automation.

  • on_page (Optional, Action): An action to be performed after a page change. See Nextion Automation.

  • on_touch (Optional, Action): An action to be performed after a touch event (press or release). See Nextion Automation.

Rendering Lambda

With Nextion displays, a dedicated chip on the display itself does the whole rendering. ESPHome can only send instructions to the display to tell it how to render something and what to render.

First, you need to use the Nextion Editor to create a display file and insert it using the SD card slot. Then, in the rendering lambda, you can use the various API calls to populate data on the display:

display:
  - platform: nextion
    # ...
    lambda: |-
      // set the "value" of a component - value is always an integer
      // for example gauges represent their status using integers from 0 to 100
      it.set_component_value("gauge", 50);

      // set the text of a component
      it.set_component_text("textview", "Hello World!");

      // set the text of a component with formatting
      it.set_component_text_printf("textview", "The uptime is: %.1f", id(uptime_sensor).state);

Note

Although you can use the rendering lambda most, if not all, updates to the Nextion can be handled by the individual Nextion components. See Below

Please see Formatted Text for a quick introduction into the printf formatting rules and Displaying Time for an introduction into the strftime time formatting.

Lambda Calls

Several methods are available for use within lambdas; these permit advanced functionality beyond simple display updates. See the full API Reference for more info.

The developer tools in Home Assistant can be used to trigger the update. The below code block is an example on how to set this up.
api:
  actions:
    - action: update_nextion
      then:
        - lambda: 'id(nextion1)->upload_tft();'

  • update_all_components(): All the components will publish their states.

    id(nextion1).update_all_components();

  • update_components_by_prefix(std::string page): This will send the current state of any component_name matching the prefix. Some settings like background color need to be resent on page change. This is a good hook for that.

    id(nextion1).update_components_by_prefix("page0.");

  • set_nextion_sensor_state(NextionQueueType queue_type, std::string name, float state); : Sets the sensor state. See Queue Types

  • set_nextion_sensor_state(int queue_type, std::string name, float state); : Sets the sensor state. See Queue Types

  • set_nextion_text_state(std::string name, std::string state); : Sets the text sensor state

Note

Below is a method for HASS to send updates to the Nextion by code.

# Enable Home Assistant API
api:
  actions:
    - action: set_nextion_sensor
      variables:
        nextion_type: int
        name: string
        state: float
      then:
        - lambda: |-
            id(nextion1).set_nextion_sensor_state(nextion_type,name,state);
    - action: set_nextion_text
      variables:
        name: string
        state: string
      then:
        - lambda: |-
            id(nextion1).set_nextion_text_state(name,state);
Queue Types:

  • SENSOR 0

  • BINARY_SENSOR 1

  • SWITCH 2

  • TEXT_SENSOR 3

  • WAVEFORM_SENSOR 4

  • NO_RESULT 5

Nextion Automation

With Nextion displays, it’s possible to define several automation actions. Depending on your setup, you may or may not need to use some of them.

on_setup

This automation will be triggered once ESP establishes a connection with Nextion. This happens after a boot up and may take some noticeable time (e.g. hundreds of milliseconds) to establish a connection over UART. Typical use scenario for this automation is choosing of the initial page to display depending on some runtime conditions or simply showing a page with a non-zero index (Nextion shows page 0 by default and ESPHome will use start_up_page on connection, if set).

wifi:
  ap: {} # This spawns an AP with the device name and mac address with no password.

captive_portal:

display:
  - platform: nextion
    id: disp
    on_setup:
      then:
        lambda: |-
          // Check if WiFi hot-spot is configured
          if (wifi::global_wifi_component->has_sta()) {
            // Show the main page
            id(disp).goto_page("main_page");
          } else {
            // Show WiFi Access Point QR code for captive portal, see https://qifi.org/
            id(disp).goto_page("wifi_qr_page");
          }

on_sleep / on_wake

The action is called before and after Nextion goes to sleep mode. Nextion is not responsive while in sleep mode. Use these triggers to prepare your code for that and force-update the on-screen content once it’s back.

on_page

This automation is triggered when a page is changed on the Nextion display. This includes both ESP and Nextion initiated page changes. ESP initiates a page change by calling goto_page("page_name") or goto_page(page_id) function. Nextion can change pages as a reaction to user’s activity (e.g. clicks) or using a timer. In either case, this automation can be helpful to update on-screen controls for the newly displayed page.

If you fully own your Nextoin HMI design and follow the best practice of setting the components’ vscope to global in the Nextion Editor, you’ll probably never need this trigger. However, if this is not the case and all / some of your UI components have local visibility scope, on_page will be your remedy. Here you can initiate updates of the relevant components.

Before actually updating components, you need to understand which page Nextion was switched to. x argument will contain a page id integer. Once you know the page id, it’s time to update the components. Two strategies would be possible. The first one is to use Nextion Sensors for every UI field and use one of the update functions. The second is to manually set component text or value for each field:

on_page:
  then:
    lambda: |-
      switch (x) {
        case 0x02: // wifi_qr_page
          // Manually trigger update for controls on page 0x02 here
          id(disp).set_component_text_printf("qr_wifi", "WIFI:T:nopass;S:%s;P:;;", wifi::global_wifi_component->get_ap().get_ssid().c_str());
          break;
      }

on_touch

This automation is triggered when a component is pressed or released on the Nextion display.

The following arguments will be available:

  • page_id: Contains the id (integer) of the page where the touch happened.

  • component_id: Contains the id (integer) of the component touched. It’s required that the component have “Send Component ID” enabled either for “Touch Press Event” and/or “Touch Release Event”.

  • touch_event: It will be true for a “press” event, or false for a “release” event.

on_touch:
  then:
    lambda: |-
      ESP_LOGD("nextion.on_touch", "Nextion touch event detected!");
      ESP_LOGD("nextion.on_touch", "Page Id: %i", page_id);
      ESP_LOGD("nextion.on_touch", "Component Id: %i", component_id);
      ESP_LOGD("nextion.on_touch", "Event type: %s", touch_event ? "Press" : "Release");

Uploading A TFT File

This will download the file from the tft_url and will transfer it over the UART to the Nextion. Once completed both the ESP and Nextion will reboot. During the upload process esphome will be unresponsive and no logging will take place. This uses the same protocol as the Nextion editor and only updates the changes of the TFT file. If HTTPS/SSL is enabled it will be about 1kB/sec.

Warning

If Hardware UARTs are not available then inconsistent results WILL occur. Lowering the speed to 9600 baud may help.

To host the TFT file you can use Home Assistant itself or any other web server. HTTPS, while always recommended on any network, will greatly reduce the upload speed.

Home Assistant

To host the TFT file from Home Assistant, create a www directory if it doesn’t exist in your config directory. You can create a subdirectory for those files as well.

For example if the file is located under your configuration directory www/tft/default.tft the URL to access it will be http(s)://your_home_assistant_url:port/local/tft/default.tft

NGINX

NGINX

The below NGINX example configuration will serve files out of the /var/www/nextion directory.

server {
  listen 80;
  access_log  /var/log/nginx/nextion_access.log;
  error_log  /var/log/nginx/nextion_error.log;
  root /var/www/nextion;
}

Components

This library supports a few different components allowing communication back and forth from HA <-> MCU <-> Nextion.

Note

If the Nextion is sleeping or if the component was set to be hidden, it will not update its components even if updates are sent. After the Nextion wakes up, all components will send their states to the Nextion to get around this.

With the exception of the Nextion Binary Sensor Component that has the page_id/component_id options configured, the example below illustrates:

  • Polling the Nextion for updates

  • Dynamic updates sent from the Nextion to the ESP device

sensor:
  - platform: nextion
    nextion_id: nextion1
    name: "n0"
    component_name: n0
  - platform: nextion
    id: current_page
    name: "current_page"
    variable_name: dp
    update_interval: 1s

Note that the first one requires a custom protocol to be included in the Nextion display’s code/configuration. See the individual components for more detail.

See Also