STM32F411 too fast in 8bit port-mode?

[jho59]

Hi,

does a STM32F411CEUS "BlackPill" knock down a TFT display because it is too fast?

For my test I'm using:

• Arduino IDE 2.3.2
• STM32duino package 2.7.1
• TFT_eSPI 2.5.43
• Setup35_ILI9341_STM32_Port_Bus.h
• STM32F411CEUS board, SYSCLK = 96 MHz, HCLK = 96 MHz
• 3.2inch TFT with ILI9341 320x240 pixel like this: http://www.lcdwiki.com/3.2inch_16BIT_Module_ILI9341_SKU:MRB3205

Connections between STM32F411 and display are correct. Sketches Julia_Set.ino and TFT_ArcFill.ino are working fine.

But I got problems with TFT_graphicstest_PDQ.ino - I guess that is the sketch everyone is using for speed test?

I only see the skull at beginning and then only a white screen. There is a report at serial monitor of ArduinoIDE. When test repeats nothing on display.

So in testFillScreen() I add a 1 ms delay after each tft.fillScreen command. The different colours are still too fast for my eyes, but I can see afterwards some text and patterns up to "something green". Then again display is only white and no visible repeat.

Is STM32F411 too fast for this display?
In datasheet of ILI9341 I see a lot of values in the range of 15 - 100 ns.
After each call of a function I used a tft.init() - now I can see the complete graphic test.

I also use variable total to sum up values of all indivudual tests:

Bodmer's TFT_eSPI library Test!
SYSCLK: 96000000 HCLK : 96000000

Benchmark Time (microseconds)
HaD pushColor 117336
Screen fill 5256
Text 8792
Pixels 148300
Lines 161320
Horiz/Vert Lines 2445
Rectangles (outline) 1848
Rectangles (filled) 54413
Circles (filled) 18863
Circles (outline) 15664
Triangles (outline) 10255
Triangles (filled) 27941
Rounded rects (outline) 7375
Rounded rects (filled) 58562
Done!
Gesamtdauer: 638370