Controlling display brightness in the lcd_pcf8574 library

ESPHome
1

Hi all.
I have a Futaba M204SD02A VFD display. Its interface is compatible with the lcd_base library.
Its difference is that it is a vacuum fluorescent display. Accordingly, its brightness can be adjusted.
I improved this library to adjust brightness and added the set_brightness function.
lcd_display.h

  void set_brightness(uint8_t brightness);

lcd_display.cpp

void LCDDisplay::set_brightness(uint8_t brightness) {
  //BR1, BR0 =  0,0:  Sets the luminance level to 100%. 
  //     0,1:  Sets the luminance level to 75%. 
  //     1,0:  Sets the luminance level to 50%. 
  //     1,1:  Sets the luminance level to 25%.
  uint8_t display_function = LCD_DISPLAY_COMMAND_FUNCTION_SET;

  // brightness=0 Minimum brightness
  // brightness=3 Maximum brightness
  // invert 2 least significant bits
  brightness ^= 3;

  if (!this->is_four_bit_mode())
    display_function |= LCD_DISPLAY_FUNCTION_8_BIT_MODE;

  if (this->rows_ > 1)
    display_function |= LCD_DISPLAY_FUNCTION_2_LINE;

  this->command_(display_function | brightness);
}

Usage example:

display:
  - platform: lcd_pcf8574
    id: vfd
    dimensions: 20x4
    address: 0x27
    update_interval: 4s
...
sun:
  latitude: xx
  longitude: yy
  on_sunrise:
    - then:
        - logger.log: Good morning!
        - lambda: |-
            id(vfd).set_brightness(3);
  on_sunset:
    - then:
        - logger.log: Good evening!
        - lambda: |-
            id(vfd).set_brightness(0);

I would appreciate it if you could add this type of display to the library in future updates.

2

Who is ‘you’ in your last sentence. If you want to get your changes (and this device) added to ESPHome, you have to create a Pull Request (PR). See Contributing — ESPHome.

3

I’m not smart enough to write the complete library code. But I suspect that the choice of model can be made by analogy with the ssd1306_base.h library