Adafruit Qualia ESP32-S3 for TTL RGB-666 Displays

Everyone loves big screens - and the Adafruit Qualia ESP32-S3 for TTL RGB-666 Displays delivers. Featuring an impressive maximum resolution of 320x480, this breakout board integrates easily with a range of microcontrollers. However, if you need to go bigger, the Qualia can support TTL interfaces, meaning no internal memory buffer - just direct access over a 16/18/24-pin interface.

TTL RGB displays can be significant in size, ranging from 4.3" 480x272 to 800x480, 800x600, and even 720x720. For larger displays, video RAM of 1MB or more is needed, plus adequate GPIO pins and a peripheral that can DMA the video RAM to the display nonstop. This technology has traditionally been used with powerful microcontrollers and microcomputers, seen in such applications as cell phones or in-car navigation systems. However, it has been difficult to implement in low-cost microcontrollers - until now!

The ESP32-S3 is a cost-effective microcontroller that provides a built-in peripheral capable of driving TTL displays and packing sufficient PSRAM to store large images. Adafruit's Qualia ESP32-S3 for TTL RGB-666 Displays utilizes an S3 module with 16 MB Flash and 8 MB octal PSRAM. Utilize the integrated RGB display peripheral to showcase graphics, images, animations, and even video (cinepak, of course!) with near-immediate updates as the entire screen updates at ~30FPS.

This dev board is designed to make it easy for you to explore displays that use the "secondary standard' 40-pin RGB-666 connector. This pin order is most commonly seen on square, round and bar displays. You'll want to compare the display you're using to this datasheet, if it matches you'll probably be good! One nice thing about this connector ordering is that it also includes pins for capacitive touch overlay, and we wire those up to the ESP32-S3's I2C port so you can also have touch control with your display.

Don't forget! This is just the development board, a display is not included. Use any RGB-666 pinout display with or without a touch overlay. Note that you will need to program in the driver initialization code, dimensions, and pulse widths in your programming language. Here are some known-working displays that you can use in Arduino or CircuitPython:

• 2.1" 480x480 Round with Capacitive Touch
• 2.1" 480x480 Round without touch
• 4" 720x720 Square with Capacitive Touch
• 4" 720x720 Round without touch
• 4.6" 960x320 Rectangular Bar

On the Qualia board we have the S3 modules, with 16 pins connected to the TFT for 5-6-5 RGB color, plus HSync, VSync, Data Enable and Pixel Clock. There's a constant current backlight control circuit using the TPS61169 which can get up to 30V forward voltage and can be configured for 25mA-200mA in 25mA increments (default is 25mA). Power and programming is provided over a USB C connector, wired to the S3's native USB port. For debugging, the hardware UART TX pin is available as well.

Since almost every GPIO is used, and almost all RGB-666 displays need to be initialized over SPI, we put a PCA9554 I/O expander on the shared I2C bus. Arduino or CircuitPython can be instructed on how to use the expander to reset and init the display you have if necessary. The remaining expander pins are connected to two right-angle buttons, and the display backlight. 

The expander is what lets us have a full 4-pin SPI port and two more analog GPIO pins - enough to wire up an MMC in 1-wire SDIO mode along with an I2S amplifier to make an A/V playback demo. Maybe we can even eat ice cream while watching kitten vids! There is also the shared I2C port, we provide a Stemma QT / Qwiic port for easy addition of any sensor or device you like.