Working with Embedded Sync Codes

[eng23]

Hi,

I have DCMI working with external sync, but what I get in memory is the video data with the sync codes (0xFF 00 00 YY). So in this case I needed to implement a code to extract this sync codes to get only the active video, but it waste processor resources..

How can I get only active vide data? I tried to work with embedded sync, but it didn't work.

According to AN5020 page 41 the embedded mode shows the frame structure that I receive in external sync mode...

Thanks

[waclawek.jan]

> I tried to work with embedded sync,

How exactly did you set the registers? If you use some "library", read out the registers' content and check against the RM.

> but it didn't work.

What were exactly the symptoms?

JW

[eng23]

Hi @Community member​ 

Thanks for reply.

Below you can find my DCMI init for embedded sync mode:

	hdcmi.Instance = DCMI;
	hdcmi.Init.SynchroMode = DCMI_SYNCHRO_EMBEDDED;
	hdcmi.Init.PCKPolarity = DCMI_PCKPOLARITY_RISING;
	hdcmi.Init.VSPolarity = DCMI_VSPOLARITY_HIGH;
	hdcmi.Init.HSPolarity = DCMI_HSPOLARITY_HIGH;
	hdcmi.Init.CaptureRate = DCMI_CR_ALL_FRAME;
	hdcmi.Init.ExtendedDataMode = DCMI_EXTEND_DATA_8B;
	hdcmi.Init.JPEGMode = DCMI_JPEG_DISABLE;
	hdcmi.Init.ByteSelectMode = DCMI_BSM_ALL;
	hdcmi.Init.ByteSelectStart = DCMI_OEBS_ODD;
	hdcmi.Init.LineSelectMode = DCMI_LSM_ALL;
	hdcmi.Init.LineSelectStart = DCMI_OELS_ODD;
 
	  hdcmi.Init.SyncroCode.FrameEndCode = 0xB6;
	  hdcmi.Init.SyncroCode.FrameStartCode = 0xAB;
	  hdcmi.Init.SyncroCode.LineStartCode = 0x80;
	  hdcmi.Init.SyncroCode.LineEndCode = 0x9D;

The sync codes (linestart, lineend...) is according to ITU656 pattern, I'm using ADV7182.

The symptoms is:

1- I can't sync the data on the display, I can see that is image data valid, but it is not synchronized...

2- I'm using FrameEvent interrupt, and in embedded sync mode I have interrupt each 5 seconds, so it is very strange..

Here is my DMA init too:

    /* DCMI Init */
    hdma_dcmi.Instance = DMA2_Stream1;
    hdma_dcmi.Init.Channel = DMA_CHANNEL_1;
    hdma_dcmi.Init.Direction = DMA_PERIPH_TO_MEMORY;
    hdma_dcmi.Init.PeriphInc = DMA_PINC_DISABLE;
    hdma_dcmi.Init.MemInc = DMA_MINC_ENABLE;
    hdma_dcmi.Init.PeriphDataAlignment = DMA_PDATAALIGN_WORD;
    hdma_dcmi.Init.MemDataAlignment = DMA_MDATAALIGN_WORD;
    hdma_dcmi.Init.Mode = DMA_CIRCULAR;
    hdma_dcmi.Init.Priority = DMA_PRIORITY_VERY_HIGH;
    hdma_dcmi.Init.FIFOMode = DMA_FIFOMODE_ENABLE;
    hdma_dcmi.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
    hdma_dcmi.Init.MemBurst = DMA_MBURST_INC4;
    hdma_dcmi.Init.PeriphBurst = DMA_PBURST_SINGLE;

Regards,

Anderson

[waclawek.jan]

I mean, read out the registers' content from DCMI.

JW

[eng23]

Hi,

Yes, I've checked, but I couldn't sync with my code adapt from the external sync mode.

I tried to use LineEvent interrupt too..

Thanks,

Anderson