ILI9341 color TFT

The 2.4 inch 240x320 color TFT panel, over 4-wire SPI. DC says whether a byte is a command or data; everything else follows from that one line.

SPI mode 0, MSB first: MOSI is sampled on the rising edge of SCK while CS is low, and a rising CS throws away a part-built byte, the way a real controller drops a frame that ends early.

Pins

Pin	What it does
VCC	Supply.
GND	Ground.
CS	Chip select, active low.
RST	Reset.
DC	Low for a command byte, high for its data or for pixels.
SCK	SPI clock.
MOSI	SPI data in.
MISO	Present on the header, never driven; this model answers no register reads.
LED	The backlight; pulling it low blanks the panel.

Properties

None. Behavior comes entirely from the command stream.

What the model gets right

MADCTL (command 0x36) is the whole of "rotation" on this controller: MV exchanges the two axes and MX/MY count the other way along them, and the frame handed to the display is always in the address counter's own coordinates, so the picture is upright whichever rotation the sketch chose. A module you rotate on the bench is a part you rotate on the canvas. CASET/PASET set the pixel window and RAMWR streams pixels into it, exactly as the datasheet has it.

What it does not model

BGR (a MADCTL bit some panels use for their color filter order) is accepted but has no effect: a pixel is always the RGB565 value that was written. The long init sequences every library sends (power control, gamma, frame rate, VCOM) are accepted and their parameters ignored, so a driver that sends a wrong or incomplete init gets a perfect picture here and whatever the panel feels like on the bench.

No timing at all on the bus. SCK has no maximum rate, CS has no setup or hold requirement, and a byte is latched the instant its eighth rising edge arrives. A real ILI9341 wants SWRESET followed by 5 ms of quiet and SLPOUT followed by 120 ms before it will take pixels; here both take effect immediately, so a driver that skips those waits works here and not on a real module. There is no frame rate, no tearing signal and no TE pin.

Also absent: vertical scrolling (0x33/0x37), partial mode, idle mode, tearing effect control, and gamma or VCOM having any visible effect. COLMOD accepts both 16-bit and 18-bit pixel formats, but a pixel is stored as RGB565 either way, so 18-bit mode loses the two extra bits per channel a real panel would keep. There is no backlight brightness. LED is on or off, not a PWM dimmer.

Common mistakes

Forgetting LED is a real pin here, not a decoration. A driver that never sets it high leaves the panel dark even while the framebuffer is being drawn correctly underneath.

See it in action

Snake, D-pad pong and Pong, two buttons all draw to an ILI9341 panel. Open them at /templates.