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Date of registration: Apr 6th 2018

Posts: 10


Monday, April 9th 2018, 5:53pm



I am using STM32F769BIT6 processor along with 7inch orient LCD 800*480. i am trying to port STEMWIN lib on it. since the LCD is interfaced in RGB, i am using lin driver.
1. i used GUIDRV_LIN_16 & GUICC_M565, i can draw pixel by pixel in 200*480 active region for layer0. I am also using FMC based external 256Mb SDRAM for Frame buffer.
the problem is when i am increasing the X axis more than 200, the drawn image is shaking and i am not able to make out what is drawn, pixels are scattered.

2. when i use GUIDRV_LIN_24 / 32 & GUICC_M888 / GUICC_M8888, i am not able to draw anything.

can anybody help what could be the issue as i am not doubting the LTDC controller config for LCD as when i jus set internal flash as frame buffer i could see full 800*480 image without any STEMWIN.

i am attaching my files, kindly suggest me where could be the issue.

sanjeev majumdar has attached the following file:
  • New (18.19 kB - 33 times downloaded - Last download: Yesterday, 5:29am)

SEGGER - Schoenen

Super Moderator

Date of registration: Aug 13th 2015

Posts: 584


Thursday, April 12th 2018, 10:26am


This sounds like a problem related to an overload of the bus the SDRAM and the DMA2D is connected to. We experienced this also on the STM32F4xx and on the STM32F746. The only solution we have found is to reduce the workload on the bus. Try to keep the layer as small as possible and to avoid unnecessary drawing operations.

It seems the function GetPixelFormat() returns only values for 16 bit per pixel. When the LCD controller gets initialized it always gets configured for 16bpp. But if emWin is configured for more than 16bpp it will fail because both components (emWin and the LCD controller) are configured differently.