Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

DE2 Video In SAV EAV

I'm trying to implement a video in/TV in decoder for the DE2 board.

Do I need to configure the decoder chip every time I load my design or can I just use the "default" settings?

The problem I am having is to do with detecting the SAV and EAV codes.

I am checking for a sequence of 0xFF, 0x00, 0x00, and then the 8 bit SAV or EAV. Using signal tap I can see that this detects the codes I would expect MOST of the time, but sometimes I notice problems.

For e.g. Sometimes Where I expect a SAV or EAV it is not detected. Examining the incoming data shows a pattern of 0x80, 0x00, 0x00 and then the SAV or EAV I would expect. Everything seems correct appart from the first 8 bits of the sequence. There may be other similar problmes related to the SAV/EAV codes (one of the 8 bit vlaues of the sequence is incorrect).

I am using the positive edge of the 27MHz clock to sync the incloming data stream.

I've tried the TV in exmaple file and that seems to work fine so there is not a problem with the board. I don't fully understand that exmaple and I don't understand why I do not get the expected sequence of SAV and EAV codes all the time.

I would appreciate any help or advice.

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    18 years ago

    I've had a similar problem. The input data is a bit noisy.

    To fix the problem do the following.

    1. Open the assignment editor from the Assignments menu in the menubar in Quartus II.

    2. Add a new assignment with the following parameters:

    To: *

    Assignment Name: Current Strength

    Value: Minimum Current

    Enabled: Yes

    3. Recompile your design.

    Good luck

    - Blair