STM32F103 + ILI9320 + ChibiOS skipping lines

[CskZoli]

Hello!

I'm a newbie on ChibiOS + uGFX. (using Chibios 17.6.3 and uGFX 2.8)

Using an STM32F103RBT6 board with a 2.8" ILI9320 display. So far was able to make it alive and it run quite fast.

When I draw filled rectangles it is working as expected, however when I put text on the screen or just draw pixels, it skipping lines (no threads are running, just initialized os, hal and gfx, code is in main())

Tried everything to solve it myself, checked every line in corresponding board and gdisp_lld files and seems ok for me, tried enable/disable options in gfxconf.h, but no luck.

Attaching the the picture, maybe from the pattern you could advise where should I look (draw a red rectangle which is fine, then start the mandelbrot demo, which skipping lines, you see the remnants of the rectangle)

Please advise!

[Joel Bodenmann]

Hello and welcome to the µGFX community!

I assume that you're using a parallel interface with the FSMC of your STM32F103. The symptoms you're getting indicate that your bus is not running stable. Try reducing the speed / increasing the different timing values.

[CskZoli]

Hello Joel!

 

Thanks for your quick replay.

Yes, 16 parallel connected but w/o FSMC. This is a medium density device (only 64 pins) so FSMC is not implemented in it, so I wrote my own driver (attached).

This bus timing issue was my first opinion as well, so I played a lot (put delays everywhere) but did not solve the problem.

Also checked the bus with oscilloscope, and all thiming is whithin ILI9320 spec.

I think if would be a bus issue, then drawing rectangles woud be affected as well, but I can draw 1000 of them without a glitch, but maybe I'm wrong.

board_ILI9320.h

[CskZoli]

Hi,

 

Now I had some progress.

It was needed to enable the GDISP_HARDWARE_STREAM_POS to get better result, however with this setting the text rendering was corrupt.

So I adjusted the gdisp_lld_ILI9320.c file (attached) with the correct orientation and scan register settings (according to datasheet), and now in all orientation text rendered correctly.

However it is still not perfect. Is there any idea where should I look?

Can I somehow temporarily disable ChibiOS interrupts in a safe way to test if it is causing or not the issue?

gdisp_lld_ILI9320.c