4" TFT display using a ST7796s driver produces a white stripe which offsets actual screen

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1

Description

4" TFT display using a ST7796s driver produces a white stripe which offsets actual screen content. I should note that I am a noob when it comes to C. I can do some stuff on my own but nothing complex.

LVGL actually runs, but I’ve hidden most widgets so only the background color is displayed. When aligning widgets to a specific corner of the screen, they actually rotate when I change the screen orientation, which is to be expected. However I can’t explain the white “uninitialized” (?) part. I don’t even know how to search correctly for this issue. Its place on the screen is also dependent on which orientation I choose, but is always visible.

PXL_20240318_092042768.TS_exported_19840_1710759634143
PXL_20240318_092042768.TS_exported_19840_17107596341431920×1080 339 KB

I seem to have a similar issue to this thread, but I have a different setup. What else could I change to make this work? It seems to be anThis text will be hidden issue with the driver, but I can’t tell for sure.

What MCU/Processor/Board and compiler are you using?

ESP32-S3 DevKit-C, IDF 5.1.1

What do you want to achieve?

The x = 0, y = 0 screen origin is not in the correct spot

What have you tried so far?

Messing around in the driver (screen was mirrored in the x axis, but is now fixed)
Selecting ILI9488 as the driver (I’ve read that it was similar to mine, did not work)
Swapping horizontal and vertical resolution
Changing orientation

Screenshot and/or video

Link to the video:

2

I’ve also found out that somehow the frame buffer gets written correctly, but seems to get corrupted as time goes on and the display origin is offset.

Right after reset

PXL_20240320_151351673
PXL_20240320_1513516731920×1445 209 KB

A few moments later

PXL_20240320_151403108
PXL_20240320_1514031081920×1445 229 KB

3

So I have done more sanity checks. The HelloWorld .ino project from ArduinoGFX library running on Pro Micro seems to properly initialize the display, so that is not broken.

PXL_20240320_135137558
PXL_20240320_1351375581920×1445 229 KB

Is it possible to somehow “hijack” the Arduino driver and use it for LVGL on my ESP?
Any help is appreciated

4

Alright, seems as if the Blanking Porch Control was set up incorrectly. I took the commands from the ArduinoGFX’s driver, the commented line in st7796s.c was there previously.

lcd_init_cmd_t init_cmds[] = {
		...
		{0xB6, {0x80, 0x22, 0x3B}, 3},
		// {0xB6, {0x0A, 0x82, 0x27, 0x00}, 4},
		...
	};

The display is now drawn correctly, but there seems to be some shimmering on text and other elements.