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How to create a handle for the PCA9554 io_expander when using it with esp32-S3 on Adafruit Qualia board?

Posted: Fri May 31, 2024 9:55 am
by karunt
I'm using the Adafruit Qualia board with ESP32-S3. The board uses the PCA9554 io_expander to provide the SPI interface for a 40 pin LCD display (which uses the ST7701 driver). See schematics for reference:
AdaFruit Qualia Board Connections to ESP32-S3.png
Schematics for ESP32-S3-WROOM connection to LCD Display
AdaFruit Qualia Board Connections to ESP32-S3.png (481.41 KiB) Viewed 509 times
To install the SPI panel, here's the code I've got:

Code: Select all

    spi_line_config_t line_config = {
        .cs_io_type = IO_TYPE_EXPANDER,
        .cs_expander_pin = EXAMPLE_LCD_IO_SPI_CS,
        .scl_io_type = IO_TYPE_EXPANDER,
        .scl_expander_pin = EXAMPLE_LCD_IO_SPI_SCL,
        .sda_io_type = IO_TYPE_EXPANDER,
        .sda_expander_pin = EXAMPLE_LCD_IO_SPI_SDA,
        .io_expander = io_expander, //handle for io_expander
    };
What I'm struggling with is how to create this io_expander handle for the PCA9554 expander. I see a library on github for the TCA9554 expander (which is presumably the newer version of PCA9554? I'm not sure) (https://github.com/espressif/esp-bsp/tr ... er_tca9554). But I don't see a library for the PCA9554 expander. Any idea on how to go about this?

The ESP example I've got (example_rgb_avoid_tearing.c) uses the esp_lcd_panel_io_additions library (https://github.com/espressif/esp-iot-so ... _additions), which itself uses the esp_io_expander library (https://github.com/espressif/esp-bsp/tr ... o_expander) as a dependency. Any help would be greatly appreciated.