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VITC decoder using TVP5150AM1

Michael Kristensen
Prodigy 30 points
Other Parts Discussed in Thread: TVP5150AM1-EP, TVP5150AM1, TVP5150

Hi.

I'm trying to decode the VITC from a composite NTSC video signal.

The 9 bytes in the VITC should read (verified by oscilloscope and other test equipment):

09 02 09 05 09 05 05 01 9D (equal to 15h:59m:59s:29f and crc=0x9D)

The 5150 reports the first 4-5 bytes correctly but mess up the rest. The rest of the bytes are almost stable but not correct. The 5150 reads

09 02 09 05 09 08 0A 02 3A and sometimes 09 02 09 05 09 00 0A 02 3A

I use the VBI RAM values from the tvp5150am1-399572 datasheet:

VITC_NTSC_Array[]={0,0,0,0,0,0x8F,0x6D,0x49,0x63,0x94,0x08,0,0,0,0x4C,0} -- written to address 0x160 and 0x170

I have tried the VBI RAM values from the tvp5150am1-ep datasheet where byte 8 (0x63) is changed to 0x69 - without much success.

By experimenting with changing byte 8 (0x63) and 9 (0x94) we have found that the values 0x59 and 0x8D makes all but the last to bytes right (tested only on this one VITC value). The last two bytes stays at "02 3A".

The chip is TVP5150AM1PBSG4.

Patching the firmware from 04.00.00 to 04.A1.02 makes no difference.

Adding an anti aliasing filter on the input didn't seem to help.

Any ideas????

Where can I find information on the function of the VBI RAM values? It will take a very long time to go through all possible combinations...

  • 0
    TI__Mastermind 43875 points
    Michael,
    Have a look at this posting for some details on potential configuration documentation errors.
    e2e.ti.com/.../1455193

    VITC should work .

    Unfortunately we no longer have support experts to help debug this issue in any more detail.

    BR,
    Steve
  • 0 in reply to Steve Clynes
    Prodigy 30 points

    Hi Steve.

    I get an "Access Denied" when I click on the link.

    It doesn't matter if I'm logged in or not.

    Does the material have any information on the VDP RAM. The datasheet has only the default values. It even suggest that one can have custom configurations  (addr 0x1A0 and 0x1B0), but there is no mention of how to choose the values for the 16 bytes in each configuration.

    With best regards & thanks

    Michael

  • 0 in reply to Michael Kristensen
    TI__Mastermind 43875 points
    Ahh, sorry, that is an internal page.

    Here are the key points though...

    Start with the VDP application note here...
    www.ti.com/.../getliterature.tsp;fileType=pdf

    Here are the comments from the original page I referenced with corrections...
    ========================
    According the Application report (SLEA102-July 2010 “TVP5150AM1 VBI Quick Start”), WSS C-RAM settings at address 0x100 noted as “Reserved”!. But it should write C-RAM PAL WSS data at 0x100 instead of 0x110.

    Likewise for NTSC WSS it should use 0x120 instead of 0x130 shown in the example.

    Table 2. Configuration RAM Recommended Settings needs to be updated:

    Data should start with 000h and 001h reserved for WST SECAM and 020h for WST PAL B and 030h reserved and so on.

    ======================

    Hopefully this helps.

    BR,
    Steve
  • 0 in reply to Steve Clynes
    Prodigy 30 points

    Hi Steve,

    Think we found the culpit!

    It seems like the PLL_AVDD pin of the TVP5150 is quite sensitive.

    Our PCB-layout had a solid connection between DVDD, CH_AVDD and PLL_AVDD. Combined with less than perfect decoupling to GND, this probably caused noise from DVDD to disturb the PLL half way through the 9 bytes VITC message (first half was always sliced correctly).

    With a number of cuts and straps I've managed to isolate DVDD from CH_AVDD and PLL_AVDD (but decoupling is still poor). With this change and some minor modifications to the VBI configuration RAM, the NTSC VITC seems to work....     

    I changed

    VITC, NTSC 160:  00 00 00 00 00 8F 6D 49 63 94 08 00 00 00 4C 00

    to

    VITC, NTSC 160:  00 00 00 00 00 8F 6D 49 A6 7C 08 00 00 00 4C 00

    based on trial and error.... (would still like to see a datasheet describing these configuration bytes - please).

    I expect that the chip works and the need to modify the configuration is caused by poor decoupling.

    We will do a redesign of the PCB to address these issues.

    Thanks,

    Michael

  • 0 in reply to Michael Kristensen
    TI__Mastermind 43875 points

    Michael,

    Glad you are working now.

    BR,

    Steve