Why does a TFT show a white screen?
When the backlight is on but nothing is drawn, the LCD glass is transparent: the driver IC is not driving the pixels. The cause is nearly always initialization, not a broken panel.
The 9-step checklist
- Supply voltage: 3.3 V logic on most modules; 5 V logic can damage them.
- Reset timing: hold RESET low at least 10 µs, then wait 120 ms.
- CS / DC swapped: the most common wiring mistake.
- SCK / MOSI: confirm with a logic analyzer.
- Wrong driver in library: ILI9341 vs ST7789 vs ILI9488 configs are not interchangeable.
- SPI mode and speed: start at 10 MHz, mode 0.
- Panel-specific init table: especially for GC9A01 and ST7701S.
- Color depth mismatch: ILI9488 needs 18-bit over SPI.
- Backlight-only power path: some modules power the logic from a separate pin.
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Frequently asked questions
Why is my TFT white after uploading code?
The display controller is powered but not initialized. Confirm the library is configured for your exact driver IC and pins, and that reset is toggled before the init sequence.
Can a wrong SPI mode cause a white screen?
Yes. Most TFT drivers use SPI mode 0. Some modules require mode 3. Try lowering the clock to 10 MHz and testing both modes.