[SOLVED][Neowbit / STM32F401RET6] Simulating VBL interrupt ?

[shazz]

Hi,

The Neowbit has a 160 x 128 TFT color screen usable thru the pyb library (pyb.SCREEN()) and a unique method: show(fb, mode).
I'm not sure what type of TFT this is and as I don't have the source code of the SCREEN class that's pretty complicated to understand how it works behind the scene.

https://github.com/KittenBot/uf2-meowbi ... it/board.h
https://github.com/KittenBot/uf2-meowbi ... t/screen.c
I guess a ST7735

So currently I'm using show(fb,mode) to display a framebuffer it works but within a loop that's too fast. So I'd like to mimic a VBL interrupt to trigger the rasterization only when it should.

I tried using a timer callback at 60Hz but I got:

Code: Select all

>> uncaught exception in Timer(4) interrupt handler
#MemoryError:

Any suggestion on how to achieve a proper display ?
Is it the TFT Controller " Tearing Effect Output Line" signal that needs be caught ?

Thanks

[dhylands]

Your Memory error is dur to trying to allocate memory from within the ISR>
See: http://docs.micropython.org/en/latest/r ... rules.html

[shazz]

Oh... thanks for the tip...

MicroPython interrupt handlers are very restrictive.... I guess not way to update the TFT framebuffer by reading data on the SD without creating objects and appending to lists... Maybe I need a kind of shared buffer, read by the IRQ handler, filled by another mean... Going to be tricky.

[dhylands]

You'll probably be interested in schedule: http://docs.micropython.org/en/latest/l ... n.schedule which can be called from an ISR. The scheduled routine can do would all of the things that your main code can do.

[shazz]

Thanks Dave! I'll try that!