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DM6437 VLYNQ burst size

Saira
Intellectual 565 points

Hello,,


I am using VLYNQ interface to transfer PAL video from one DM6437 device to other DM6437 device. The video is transferred to the remote device but with delay. Frames got missed. 4 pins are used for the transfer but I m not able to figure out the burst size. Maximum burst size is sixteen 32-bit words. How can I set the transfer to this maximum burst size ??? From where the burst size is set ?? Is there any bit to set the burst size ??

Regards

Saira Kanwal

  • TI__Genius 14405 points

    Saira,

    Please look into the VLYNQ user guide 2.12 EDMA Event Support

    Basically, the device EDMA is used to service VLYNQ, and you need to program the EDMA parameters (please see the EDMA user guide).

    Could you please elaborate on how exactly you are doing the transfer?

    regards,

    Paul

  • in reply to Paul.Yin
    Intellectual 565 points

    Paul,

    I want to capture a video from PAL camera on one DM6437 kit and transfer that video to other DM6437 using VLYNQ interface and wants to display there in real time...

    In "TMS320DM643x DMP VLYNQ Port User's Guide Literature Number: SPRU938B" http://www.ti.com/lit/ug/spru938b/spru938b.pdf  Table B-2 Expected Throughput (VLYNQ Interface Running at 76.5 MHZ and 99 MHZ) Burst size in 32-bit words is given and throughput ratings for 1, 4, 8 and 16 32-bit word is given...... How this burst size is set to maximum that is 16 or it can be set automatically based on data... ???

    I use EDMA also to transfer but couldn't able to set ACNT, BCNT and CCNT parameters correctly...... As DM6437 captures video in YCbCr format so I set ACNT = 16, BCNT = 25920 and CCNT  = 1 for SYNC_MODE_A  to transfer only the Y (luminance) component after converting interleaved to planar... but couldn't get the desired result... In ur recommendation what would be the values for ACNT, BCNT, CCNT and MODE (A or AB) ????

    Regards

    Saira

  • in reply to Saira
    TI__Genius 14405 points

    Hi Saira,

    I would recomment you start with ACNT = 64 (bytes).

    The DM6437 EDMA TC burst size is not configurable. However, different TC have different default burst sizes. If you want burst size to be 64 bytes, you can use TC2. Please see section 2.11.4 of the EDMA user guide for more information.

    regards,

    Paul