STM32F discovery and small bitmaps

[mauricemennings]

Posted on March 15, 2016 at 14:35

Hi, i'm working with the STM32F746 discovery board and i want to display bitmaps from sd card to the screen.

Using the example LTDC_PicturesFromSDCard i've managed to display 24 bit bitmaps on screen, however when the bitmap files are smaller than 80 x 80 pixels the images get display wrong. they then look tilted and under a angle of 30 degrees to the right (like italic letters)! When i use the smaller bitmaps in the demo LTDC_PicturesFromSDCard they also are tilted the same. who knows whats wrong here ? #!stm32 #bitmap-pixels

[Tesla DeLorean]

Posted on March 15, 2016 at 17:40

You'd need to validate the header contents of the file, and the rasters it describes. If those are demonstrably valid, then you need to look at the software code and how it is handling those parameters.

[mauricemennings]

Posted on March 16, 2016 at 08:17

I've compared the bitmaps in hex, the headers are fine.

i even rescaled a bitmap from 100 * 100 pixels to 50 * 50 pixels, with irfanview so the are the same but still the  bitmap of 50 * 50 is not displayed correct. if you try the example program : LTDC_PicturesFromSDCard which is provided as sample with the discovery board you get the same result if you use  smaller bitmaps.