[ADV7441A]Output VSYNC behavior after video signal input.

Hi Takuya San,

         Please let us know, Are you facing this Vsync lost issue only with RS170A or any other normal standard (CVBS/YC) ?

Thanks,

Poornima

Hi Poornima-san.

In our application we use only RS170A and have not checked it with other video standards.

Best regards.

Takuya

Hi Takuya San,

  Generally 'Vsync' to be low only when format change.

  Please let us know, whether you can able to observe the stable video without any issues during such scenario ?

  Also could you please configure the Vsync/Hsync related register configuration according to the reference script at 4682.ADV7441A_Evaluation_Board_Documents.zip

 Refer 'Table59' for Hsync/Vsync Recommended user settings for NTSC and let us know the result.

Thanks,

Poornima

Hi Takuya San,

  Generally 'Vsync' to be low only when format change.

  Please let us know, whether you can able to observe the stable video without any issues during such scenario ?

  Also could you please configure the Vsync/Hsync related register configuration according to the reference script at 4682.ADV7441A_Evaluation_Board_Documents.zip

 Refer 'Table59' for Hsync/Vsync Recommended user settings for NTSC and let us know the result.

Thanks,

Poornima

Hi Poornima-san

The video is output without any problem when this event occurs.
I asked this question because I am using software to determine if Vsync is interrupted, and I wanted to know the mechanism by which this event occurred.
The setting was left at the default, so I set the value in Table 59, but the event did not change.

Best Regards.

Takuya

Hi Takuya San,

         Have you crosscheck your software with reference script which are related to Sync configuration ? Please check with other video standards too then we can able to track it easily.

         If possible, Could you please check the same in our eval board.

Thanks,

Poornima

Hi Poornima-san

Sorry, I didn't know which part of the reference script I should check.

Could you tell me which part I should check specifically?

Also, since I don't have an eval board, I can't check it with an eval board.

Best Regards.

Takuya

Hi Takuya San,

             Please refer the reference script at 4682.ADV7441A_Evaluation_Board_Documents.zip .

Also If possible Please check with other standard like PAL or NTSC to check whether the same scenario is observed in other video standards too.

Thanks,

Poornima

Poornima-san

Our application sets the video input manually (SETADC_SW_MAN_EN=1)
Therefore, I didn't know which setting to apply in the script I received.
The pin assignment and specifications of the input video signal are as follows.

*Video Specifications
ADV Input : RS-170A compliant RGB color analog video(Sync on Green)
Number of Pixels : Stripe 720px * 480px
Display Color : RGB
Gradation : 1024
Scanning Format : Interlace
Horizontal scanning period : 2 * fSC / 455(fSC=3.579545MHz +/-50ppm)
Vertical scanning period : 2 * fH / 525

*Pin Assignment
Ain1:RS-170A(Green)
Ain2=RS-170A(Blue)
Ain3=RS-170A(Red)
SOG=RS-170A(Green)

The register is set by the following script.
Are there any problems or missing settings?
Target Address : 0x40(ALSB = Low)
40 00 00
40 03 11
40 05 00
40 06 0A
40 87 AD
40 88 AC
40 1D 40
40 6A 4F
40 3C 5A
40 47 0A
40 67 01
40 68 F2
40 7B 04
40 7D 03
40 7E 03
40 8F 00
40 F3 07
40 8A 10
40 85 19
40 C3 31
40 C4 C2
40 73 17
40 74 25
40 75 C9
40 76 72
40 6C 10
40 6D 00
40 6E 00
40 6F 00
40 70 00
40 BF 16
40 C0 00
40 C1 00
40 C2 00
40 6C D4
40 6D F4
40 6E 4F
40 6F 44
40 70 F4
40 0C 34
40 31 1A
40 32 81
40 35 00
40 36 7D
40 37 A1
40 E5 41
40 E6 84
40 E7 06

Best Regards.

Takuya

Hi Takuya San,

   Could you please do the below register configuration according to the reference script and let us know the result.

##CP 1080p##:1080p/60Hz RGB In 1X1 30Bit 444 RGB Out through DAC:

42 03 0C ; Disable TOD
42 05 01 ; Prim_Mode =001b COMP
42 06 04 ; VID_STD=00100 (720x480)
42 1D 40 ; Disable TRI_LLC
42 37 00 ; Disable PCLK
42 3C A8 ; SOG Sync level for atenuated sync, PLL Qpump to default
42 47 0A ; Enable Automatic PLL_Qpump and VCO Range
42 67 01 ; RGB Full Range Input Colour Space
42 68 F2 ; Auto CSC , RGB Out
42 7B 14 ; TURN OFF EAV & SAV CODES
42 85 02 ; Autodetect Sync Source
42 C3 31 ; Manual Muxing
42 C4 F2 ; Manual Muxing
42 BA A0 ; Enable HDMI and Analog in
42 F4 15 ; Max Drive Strength
54 00 FD ; power down encoder
50 10 01 ; DAC channel enabled

Also please note "Most of our video decoders can able to handle RS-170, Since it's basically an NTSC without color. You'll get NTSC timings out of it. ADV7441A, with Color Kill turned on-- RS170 should work".

Thanks,

Poornima

Hi Poornima-san

As a result of investigating multiple patterns based on the register setting values you provided, the event no longer occurs by setting DS_OUT to 0.
From this result, can you deduce the mechanism of the phenomenon that was the problem this time?
Setting DS_OUT to 0 makes LLC and VS out of sync, which is undesirable in our application.
Is there any other way to avoid this?

Best Regards.

Takuya

Hi Takuya San,

        Please ensure, How H&V synchs from your source connected to the ADV7441A ? Also you will get asynchronous VS output if DS_OUT to '0' 

       DS_OUT bit then enables selection between a synchronous VS signal (synchronous to True Line Locked Clock) and an asynchronous version of the vertical synchronization. Depending on the application and the ultimate purpose of the timing signal, both of them can have distinct advantages.

    DS_OUT signal selects between the following signals:
       Asynchronous composite-style synchronization signal derived from either the digital HS and VS or the embedded synchronization (SOG). Macrovision impairments may be present.
       Sequence of generated horizontal synchronization pulses where Macrovision impairments,
such as pseudo-synchronization pulses, have been removed.

Thanks,

Poornima

Hi Poornima-san

It uses the SOG pin as a sync source.

This signal connects the analog input green signal through a 1nF capacitor. This connection is based on the circuit on the evaluation board.

I understand that setting DS_OUT to 0 will generate VS_OUT synchronous to XTAL, and thus asynchronous to LLC.

What we want to know is why LLC-synchronized VS_OUT rarely asserts low after Vsync lock.

In our evaluation, when this event occurs, it always occurs in the 8th field after Vsync lock.

This phenomenon seems very logical.

If the mechanism of this event is clarified and this event always occurs only in the 8th field, countermeasures such as ignoring this event can be taken at that timing.

From the evaluation results so far, it seems to be related to LLC, but when I checked the output of LLC, it seemed to stabilize at the specified frequency before this event occurred.

In other words, I think that the signal input to SOG is sufficiently stable.

Best Regards.

Takuya

Hi,

  Its hard to find out what going wrong to make Vsync becomes low level in the 8th field after locking.

  If possible, Could you please check the same in our evaluation board and if this is reproducible in our evaluation board then we can check with part specialist about this.

Thanks,

Poornima