Waveshare ESP32-S3-Touch-LCD-7B support

[ctwohig]

Describe the problem you have/What new integration you would like

Addition of new Waveshare IO extension module

Please describe your use case for this integration and alternatives you've tried:

The ESP32-S3-Touch-LCD-7B uses pins on the module to control the backlight state and brightness of the LCD. The CS pin for the SD card is also controlled here preventing the use of it as well.

Additional context

Waveshare has released another revision of their ESP32-S3 board with a built in 7 inch display. The new model has a higher resolution 1024x600, but more importantly the ability to control the screen brightness. Previous models used a ch422g IO extender to connect to the lcd backlight enable pin but the new model has switched it out for a different chip. I've contacted Waveshare support, and all they would do is provide this info, and point to the example code.
"The ESP32 - S3 - Touch - LCD - 7B uses the CH32V003, which is a microcontroller unit (MCU), not an IO expansion chip."
The example code does contain an io_extension folder with what appears to be the drivers for interacting with their chip, I'm just not really sure how to add those via external components, but would also love to see them added to the native drivers.

This demo LVGL_UI has the example of interacting with the PWM Backlight
https://www.waveshare.com/wiki/ESP32-S3-Touch-LCD-7B#16_LVGL_UI
https://files.waveshare.com/wiki/ESP32-S3-Touch-LCD-7B/ESP32-S3-Touch-LCD-7B-Demo.zip
https://files.waveshare.com/wiki/ESP32-S3-Touch-LCD-7B/ESP32-S3-Touch-LCD-7B-Schematic.pdf

It also appears the battery voltage monitoring circuit is connected to this chip as well.
it would not allow me to attach the example code, but i have included the links. I've also included my example config, which worked 100% on the previous model, with the new model everything other than the LCD backlight control works

test32-s3-waveshare7b.zip

[KenDodman]

Have you had any luck with the backlight?
I used your code and got the 7b working, thank you.

[ctwohig]

Have you had any luck with the backlight? I used your code and got the 7b working, thank you.

Sorry, nothing yet. I have asked Waveshare about assisting with a library that may work, best i can tell the example code waveshare provides uses their own i2c library as well, so probably needs the io_extender rewritten completely.

[latonita]

@ctwohig Looks like they replaced CH422 IO expander with the MCU with more features and it supports PWM itself.
I took a look at their library.
please try the following code. it shall send PWM command, its just sends i2c pwm command to that mcu.
i mean you can put it in any lambda you want. its just and example, i have not tried it myself, i dont have the device.

switch:
  - platform: template
    name: "Test brightness"
    id: test_brightness
    turn_on_action:
      - lambda: |-
          const uint8_t IO_EXTENSION_ADDR = 0x24;
          const uint8_t IO_EXTENSION_PWM_ADDR = 0x05; // Address for the PWM output register
          
          uint8_t Value = 55; // Example brightness value
          
          auto *i2c_bus = id(bus_a);

          // function from the library
          // void IO_EXTENSION_Pwm_Output(uint8_t Value)

          // Prevent the screen from completely turning off
          if (Value >= 97)
          {
              Value = 97;
          }

          uint8_t data[2] = {IO_EXTENSION_PWM_ADDR, Value}; // Prepare the data to write to the PWM register
          // Calculate the duty cycle based on the resolution (12 bits)
          data[1] = Value * (255 / 100.0);
          // Write the 8-bit value to the PWM output register

          auto result = i2c_bus->write(IO_EXTENSION_ADDR, data, 2);
          if (result == i2c::ERROR_OK) {
            ESP_LOGI("i2c_command", "I2C command sent successfully");
          } else {
            ESP_LOGE("i2c_command", "Failed to send I2C command, error: %d", result);
          }

[latonita]

@KenDodman @ctwohig i put new draft PR
esphome/esphome#10071
please try

[agillis]

Thanks I'll try it out. Do you have some demo code to use your new driver with this screen?

[latonita]

since i dont have the device itself lets try to create a YAML for it. I would appreciate the input from those how already get base functionality working .
@agillis check yaml file posted by topic starter.

with new component what you need to do is:
find all the areas where ch422g is mentioned and replace with waveshare_io

external_components:
  - source: github://pr#10071
    components: [waveshare_io]
    refresh: 1h

...

i2c:
   - id: bus_a
     sda: 8
     scl: 9
     scan: true

output:
  - platform: waveshare_io
    id: backlight_output

light:
  - platform: binary
    id: lcdbacklight
    name: Screen
    icon: "mdi:television"
    entity_category: config
    output: backlight_output
    restore_mode: RESTORE_DEFAULT_ON
    #default_transition_length: 250ms

...


display:
...
    reset_pin:
      waveshare_io: wave_io
      number: 3
    enable_pin:
      waveshare_io: wave_io
      number: 2

....

waveshare_io:
  - id: wave_io

touchscreen:
  platform: gt911
  id: my_touch
  interrupt_pin: GPIO4
  reset_pin:
    waveshare_io: wave_io
    number: 1
    mode: OUTPUT

[agillis]

OK looks good. How do I access the PCM pin on the waveshare_io? Is it something like this?

output:
  - platform: ledc
    pin:
      waveshare_io: waveshare_io_hub
      number: 2
      mode:
        output: true
    id: gpio_backlight_pwm

Seems like I would need to change the mode to PCM instead of output: true

See my full code here

https://github.com/agillis/esphome-modular-lvgl-buttons/blob/main/modules/hardware/waveshare-esp32-s3-touch-lcd-7B.yaml

[latonita]

PWM pin is here

output:
  - platform: waveshare_io
    id: pwm_backlight_output

i think its something like that:

    light:
      - platform: monochromatic
        name: "Waveshare PWM Light"
        output: pwm_backlight_output
        id: wave_pwm_light

[agillis]

I received my screen today. I loaded the code. It sort of works but it's all backwards. When I increases the brightness it decreases. I need to turn the LED off to turn it on. But once it's on it can not be turned off.

[latonita]

I received my screen today. I loaded the code. It sort of works but it's all backwards. When I increases the brightness it decreases. I need to turn the LED off to turn it on. But once it's on it can not be turned off.

@agillis Thanks for the test. I took a look at original code and looks like this board use inverted logic.
please do the following and report

output:
  - platform: waveshare_io
    id: pwm_backlight_output
    inverted: true
    min_power: 0.03
    max_power: 1.0

waveshare lib prevents users to set more than 97% (inverted, almost dark but not dark) it might be connected with some circuit limitations. i will hardcode this limit in source file. just in case.

exio pin 2 controls backlight. on/off

switch:
  - platform: gpio
    name: "Backlight"
    id: exio2
    pin: 
      waveshare_io: wave_io
      number: 2
      mode: 
        output: true

[agillis]

output:
  - platform: waveshare_io
    id: pwm_backlight_output
    inverted: true
    min_power: 0.03
    max_power: 1.0

and

switch:
  - platform: gpio
    name: "Backlight"
    id: exio2
    pin: 
      waveshare_io: wave_io
      number: 2
      mode: 
        output: true

both work now. Is there some way to get the dimming control back?

I would like the

    light:
      - platform: monochromatic

to work.

[ctwohig]

thank you, i just tested and this worked. Reviewing the issue history looks like some additional testing and progress with other users.

…

On Mon, Aug 4, 2025 at 6:44 AM Anton Viktorov ***@***.***> wrote: *latonita* left a comment (esphome/feature-requests#3202) <#3202 (comment)> @ctwohig <https://github.com/ctwohig> Looks like they replaced CH422 IO expander with the MCU with more features and it supports PWM itself. I took a look at their library please try the following code. it shall send PWM command, its just switch: - platform: template name: "Test brightness" id: test_brightness turn_on_action: - lambda: |- const uint8_t IO_EXTENSION_ADDR = 0x24; const uint8_t IO_EXTENSION_PWM_ADDR = 0x05; // Address for the PWM output register uint8_t Value = 55; // Example brightness value auto *i2c_bus = id(bus_a); // function from the library // void IO_EXTENSION_Pwm_Output(uint8_t Value) // Prevent the screen from completely turning off if (Value >= 97) { Value = 97; } uint8_t data[2] = {IO_EXTENSION_PWM_ADDR, Value}; // Prepare the data to write to the PWM register // Calculate the duty cycle based on the resolution (12 bits) data[1] = Value * (255 / 100.0); // Write the 8-bit value to the PWM output register auto result = i2c_bus->write(IO_EXTENSION_ADDR, data, 2); if (result == i2c::ERROR_OK) { ESP_LOGI("i2c_command", "I2C command sent successfully"); } else { ESP_LOGE("i2c_command", "Failed to send I2C command, error: %d", result); } — Reply to this email directly, view it on GitHub <#3202 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AES4A6ZYFDJQ7WPVE6ADWMD3L42PZAVCNFSM6AAAAACA7SPVUWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTCNJQGA3TOMJQGI> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[ctwohig]

I've tested the waveshare_io external component and seems almost there. If i have the backlight in binary mode, it works as expected, but changing it to monochromatic doesn't work as expected. the screen can no longer be turned off, just dims and the dimming isn't really changing bellow 70%, so something seems off with that calculation

[ctwohig]

my dimming issue was my config, this config has the light working the way i want

waveshare_io:
  - id: wave_io

output:
  - platform: waveshare_io
    id: backlight_output

  - platform: waveshare_io
    id: pwm_backlight_output
    inverted: true
    min_power: 0.03
    max_power: 1.0

switch:
  - platform: gpio
    name: "Backlight"
    internal: True
    id: exio2
    pin: 
      waveshare_io: wave_io
      number: 2
      mode: 
        output: true

light:
  - platform: monochromatic
    id: lcdbacklight
    name: Screen
    icon: "mdi:television"
    entity_category: config
    output: pwm_backlight_output
    restore_mode: ALWAYS_ON
    default_transition_length: 250ms
    on_turn_on: 
      then:
        - switch.turn_on: exio2
    on_turn_off: 
      then:
        - switch.turn_off: exio2

display:
  - platform: rpi_dpi_rgb
    id: my_display
    update_interval: never
    auto_clear_enabled: false
    color_order: RGB
    pclk_frequency: 30MHZ
    dimensions:
      width: ${resolution_width}
      height: ${resolution_height}
    de_pin:
      number: 5
    hsync_pin:
      number: 46
      ignore_strapping_warning: true
    vsync_pin:
      number: 3
      ignore_strapping_warning: true
    pclk_pin: 7
    pclk_inverted: true
    reset_pin:
      waveshare_io: wave_io
      number: 3
#    enable_pin:
#      waveshare_io: wave_io
#      number: 2
    hsync_back_porch: 152
    hsync_front_porch: 48
    hsync_pulse_width: 162
    vsync_back_porch: 13
    vsync_front_porch: 3
    vsync_pulse_width: 45
    data_pins:
      red:
        - 1         #r3
        - 2         #r4
        - 42        #r5
        - 41        #r6
        - 40        #r7
      blue:
        - 14        #b3
        - 38        #b4
        - 18        #b5
        - 17        #b6
        - 10        #b7
      green:
        - 39        #g2
        - 0         #g3
        - 45        #g4
        - 48        #g5
        - 47        #g6
        - 21        #g7

touchscreen:
  platform: gt911
  id: my_touch
  interrupt_pin: GPIO4
  reset_pin:
    waveshare_io: wave_io
    number: 1
    mode: OUTPUT