Wiring for your board

Pins belong to the board

Two controls. The top one changes every number on the drawing. The bottom one — the panel size — changes nothing at all, and that is the thing worth sitting with for a moment.

The GPIO a wire lands on is a property of the board you are compiling for. The driver chip, the resolution, the offsets and the backlight polarity are properties of the glass. They never meet, so there is no combination to look up: pick your board, pick your panel, and the two answers are independent.

The library goes further and picks the board row for you, from what you selected in Tools ▸ Board. Compile for an ESP32-S3 and you get the S3 pins; compile for an ESP32 Dev Module and you get the classic ones. Nothing to edit.

The gap in the table

There are two rows and no third one. The library chooses the S3 row when it is built for an S3, and the classic-ESP32 row otherwise.

Otherwise includes the ESP32-C3, and the classic row hands out GPIO 23 for data and GPIO 32 for the backlight. A C3's pins stop at GPIO 21. Neither of those exists.

So on a C3 — and on anything else that is not one of the two named chips — the default pins are not a starting point, they are wrong, and you set them yourself:

LB_Wiring pins = LB_WIRING;   // start from the default for this chip
pins.cs   = 7;                // ...then change what your board actually has
pins.dc   = 6;
pins.rst  = 10;
pins.mosi = 3;
pins.sclk = 2;
pins.backlight = 5;

display.setWiring(pins);      // before begin()
display.begin();

Copy LB_WIRING rather than declaring an empty one. It carries an SPI bus number whose meaning is not the same on every chip, and starting from the default gives you a bus that is already correct for the chip you are building for.

printInfo() prints the pins actually in use and marks any you overrode, which turns a wiring mistake into a line in the serial log instead of a blank screen.

More than one display

Clock and data are shared. Each display gets its own CS, and DC and RST can be common. That is ordinary SPI, and it is the reason CS exists — without it, two panels on one bus both take every byte.