freeRTOS + JPEG DMA encoding problem

[Pawel Skrzypek]

Posted on August 01, 2017 at 12:06

Hi,

I am using STM32F7-Discovery board. I've written my project in freeRTOS. The JPEG DMA encoding is implemented the same way as in HAL examples.

Everything works fine until I will change freeRTOS heap size. In this case JPEG file size is much bigger than the 'correct one' and it is demaged.There is a preview in attachments:OK ONE  - filesize [216KB]BAD ONE - filesize [318KB]

Is a heap-size has an influence on DMA process? Did I forget about something?

Thanks in advice.

#dma #jpeg #encoding #freertos

[Mario Popovic_2]

Posted on January 19, 2018 at 07:47

Hi Pawel,

I'm having the same issue as you. I'm using STM32F767IG with FreeRTOS and no matter what i do I can't get the correct JPEG file. I tried to diagnose the problem with JPEGSnoop diagnostic software and i get the following error:

*** Marker: SOS (Start of Scan) (xFFDA) ***

OFFSET: 0x0000024F Scan header length = 12 Number of img components = 3 Component[1]: selector=0x01, table=0(DC),0(AC) Component[2]: selector=0x02, table=1(DC),1(AC) Component[3]: selector=0x03, table=6(DC),11(AC)ERROR: SetDhtTables(comp=3, TblDC=6 TblAC=11) out of indexed range Spectral selection = 3 .. 107 Successive approximation = 0x00

Did you manage to solve your problem? Does it have something to do with the Errata sheet section 2.13.1 (

http://www.st.com/content/ccc/resource/technical/document/errata_sheet/group0/23/a6/11/0b/30/24/46/a5/DM00257543/files/DM00257543.pdf/jcr:content/translations/en.DM00257543.pdf

 )

Regards,

Mario