Backlight control requirements

[Y1hsiaochunnn]

According to contact with a variety of screen backlight control, can be classified as the following:

• GPIO Control
  • High and Low Levels: The backlight is controlled by a GPIO pin directly, where setting it to high turns on the backlight, and setting it to low, turns it off, Or vice versa
  • PWM Signal Control: The backlight is controlled by a GPIO pin generating a PWM signal, with the brightness adjusted according to the duty cycle.
• Control via I2C Chip like custom MCU or IOExpander
  • The brightness (0x00~0xFF) is adjusted by writing to a specific register of the backlight control chip via the I2C bus.
    • Control Process: The MCU communicates with the backlight control chip over I2C and writes the brightness value to a specific register address.
• Control via QSPI or MIPI-DSI or others
  • The brightness (0x00~0xFF) is adjusted by sending the value to a specific register via the QSPI or MIPI-DSI protocol.
    • QSPI: Uses high-speed serial communication to write to the register.
    • MIPI-DSI: Typically used with integrated display control, enabling direct backlight brightness control through the MIPI protocol.

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so, i know you have the plan to implement backlight control next. Maybe you can consider the above several types of backlight control scheme? Please let me know if you need anything

[Lzw655]

Hi @Y1hsiaochunnn,

Thank you very much for your suggestions. They are extremely comprehensive. Although I haven’t encountered the last method using QSPI or MIPI-DSI protocols for control.

I also realize that the current library’s approach to backlight control, using Switch (GPIO) and PWM (LEDC) methods, doesn’t meet the requirements of many development boards. Therefore, I am restactoring this library and plan to introduce a Custom method on top of the Switch and PWM methods to accommodate different development board requirements. The expected updated configuration file is as follows:

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
///////////////////////////// Please update the following macros to configure the backlight ////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#define ESP_PANEL_USE_BACKLIGHT         (1)         // 0/1
#if ESP_PANEL_USE_BACKLIGHT
/**
 * Backlight control mode. Choose one of the following:
 *  - ESP_PANEL_BACKLIGHT_TYPE_SWITCH_GPIO: Use GPIO switch to control the backlight, only support on/off
 *  - ESP_PANEL_BACKLIGHT_TYPE_PWM_LEDC:    Use LEDC PWM to control the backlight, support brightness adjustment
 *  - ESP_PANEL_BACKLIGHT_TYPE_CUSTOM:      Use custom function to control the backlight
 *
 */
#define ESP_PANEL_BACKLIGHT_TYPE        (ESP_PANEL_BACKLIGHT_TYPE_PWM_LEDC)

#if ESP_PANEL_BACKLIGHT_TYPE != ESP_PANEL_BACKLIGHT_TYPE_CUSTOM
/* IO num of backlight pin */
#define ESP_PANEL_BACKLIGHT_IO          (47)
#define ESP_PANEL_BACKLIGHT_ON_LEVEL    (1)         // 0: low level, 1: high level
#else
/**
 * @brief Custom backlight control function
 *
 * @param[in] percent   Brightness percentage, 0-100
 * @param[in] user_data User data, default is a pointer of `Board`
 *
 */
#define ESP_PANEL_BACKLIGHT_CUSTOM_FUNCTION( percent, user_data )  \
    {  \
        Board *board = static_cast<Board *>(user_data);  \
    }
#endif /* ESP_PANEL_BACKLIGHT_TYPE */

/* Set to 1 if you want to turn off the backlight after initializing the panel; otherwise, set it to turn on */
#define ESP_PANEL_BACKLIGHT_IDLE_OFF    (0)         // 0: on, 1: off

#endif /* ESP_PANEL_USE_BACKLIGHT */

[Y1hsiaochunnn]

Hi @Y1hsiaochunnn,

Thank you very much for your suggestions. They are extremely comprehensive. Although I haven’t encountered the last method using QSPI or MIPI-DSI protocols for control.

I also realize that the current library’s approach to backlight control, using Switch (GPIO) and PWM (LEDC) methods, doesn’t meet the requirements of many development boards. Therefore, I am restactoring this library and plan to introduce a Custom method on top of the Switch and PWM methods to accommodate different development board requirements. The expected updated configuration file is as follows:

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
///////////////////////////// Please update the following macros to configure the backlight ////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#define ESP_PANEL_USE_BACKLIGHT         (1)         // 0/1
#if ESP_PANEL_USE_BACKLIGHT
/**
 * Backlight control mode. Choose one of the following:
 *  - ESP_PANEL_BACKLIGHT_TYPE_SWITCH_GPIO: Use GPIO switch to control the backlight, only support on/off
 *  - ESP_PANEL_BACKLIGHT_TYPE_PWM_LEDC:    Use LEDC PWM to control the backlight, support brightness adjustment
 *  - ESP_PANEL_BACKLIGHT_TYPE_CUSTOM:      Use custom function to control the backlight
 *
 */
#define ESP_PANEL_BACKLIGHT_TYPE        (ESP_PANEL_BACKLIGHT_TYPE_PWM_LEDC)

#if ESP_PANEL_BACKLIGHT_TYPE != ESP_PANEL_BACKLIGHT_TYPE_CUSTOM
/* IO num of backlight pin */
#define ESP_PANEL_BACKLIGHT_IO          (47)
#define ESP_PANEL_BACKLIGHT_ON_LEVEL    (1)         // 0: low level, 1: high level
#else
/**
 * @brief Custom backlight control function
 *
 * @param[in] percent   Brightness percentage, 0-100
 * @param[in] user_data User data, default is a pointer of `Board`
 *
 */
#define ESP_PANEL_BACKLIGHT_CUSTOM_FUNCTION( percent, user_data )  \
    {  \
        Board *board = static_cast<Board *>(user_data);  \
    }
#endif /* ESP_PANEL_BACKLIGHT_TYPE */

/* Set to 1 if you want to turn off the backlight after initializing the panel; otherwise, set it to turn on */
#define ESP_PANEL_BACKLIGHT_IDLE_OFF    (0)         // 0: on, 1: off

#endif /* ESP_PANEL_USE_BACKLIGHT */

Maybe after some time, I can lend you a piece of product based on ESP32-S3 SH8601 QSPI communication, just to verify the function of SH8601. At present, I can't adjust it, this may be some of my Settings. This product also uses QSPI to configure the screen (of course it also supports MIPI 1-lane, but it does not do this at present, P4 may be more suitable), and changes the backlight by modifying the register 0x51

[Lzw655]

Great! I'm looking forward to it.