AdafruitGFX `fillscreen()`, `drawFastVLine()`, `drawFastHLine()` working only partially (ESP32)

[profjmer]

Sample: ScreenTFT_ILI9340-ILI9341 In that sample, fillscreen only works with color 0, all other colors draw only a very short line of the color chosen. This issue happens also with functions drawFastVLine(...) drawFastHLine(...) Drawing rectangles is also affected. Is it my setup ? Any body able to reproduce this behavior ?

[mikee47]

I've checked fillScreen(ILI9341_PURPLE) on my rp2040 board and no problems. Is your circuit connected using jumpers? If so, try reducing the clock speed (e.g. tft.begin(8000000);) see if that makes a difference. From experience, this is often the cause of display issues. Soldered connections are best.

[profjmer]

I have a pcb with the TFT board plugged on headers. I can load a bmp full screen of red dotss (220x340) then clear it with a fillscreen(0) and it will clear the screen, any other color will also clear the screen (all black) and then add a little line of the color chosen at the beginning of the screen. I have an application that worked on a esp8266 that i try to port to esp32. I can not use the old Adafruit_GFX lib and the new one has this problem. I tried with a very low freq 1M, without success. Is there another TFT library in SMING that can be used for ILI9341/ILI9488 ?

[mikee47]

Are you using the ILI9488? If so, please note that it only supports 18-bit (3-byte) colours whereas the ILI9341 uses 16-bit (2-byte). This may explain the colour problems.

If you want to try another library, see https://sming.readthedocs.io/en/latest/_inc/Sming/Libraries/Graphics/index.html. I use this with an ILI9341 2.8" display, but it has a pretty good feature set and you can test/develop directly on Host without any hardware. I haven't tried it on the ILI9488 but should only need a few tweaks to get that working. (See feature/ili9488 branch.)

[profjmer]

I am using ILI9341 and here is a picture of the latest test that I have done.

fillscreen, drawFastLine use drawline and drawline can't draw straight lines (horizontal or vertical)

Four lines have been drawn, two vertical and two horizontal. Only the lines that do not have the same x or same y coordinate are normally drawn. Those you have the same coordinate x or y draw only a partial line. I did not dig further but i guess that there is something wrong with this function.

[profjmer]

Here is the code for the lines tft.drawLine(100,0,101,320,ILI9341_RED); tft.drawLine(90,0,90,320,ILI9341_YELLOW);

    tft.drawLine(0,100,240,101,ILI9341_GREEN);
    tft.drawLine(0,120,240,120,ILI9341_BLUE);

[mikee47]

Hooked up an ESP32 and can confirm your results! Easy fix by amending the Adafruit_SPITFT::writeColor method. Delete lines 1037-1177 inclusive. Then run make Adafruit_GFX-build.