EVAL-ADV7182AEBZ_HSYNC_VSYNC_Abnormal Timing

Hi Isshinkida San,

      Generally, the timing of the HSync/VSyncs are determine what is blanking and what is active video, basically the state of VSync when there is an HSYNC transition determines whether the change is to active video or blanking and 'Vsync' to be low only when any format change.

        Please note that, We can have the certain possibilities for HSYNC/VSYNC Abnormality.

              1. There might be a problem with crystal frequency ( Is it 28Mhz or 28.63636Mhz? It has to be the right frequency.  The offset is definitely a problem as well-- if you are using the same bias circuit as the eval board it should be the same offset.  You should probably check the components in that circuit and check for shorts.

              2.  The PLL filter/Power supply is the most likely be an problem (PLL (PVDD) power supply might be an noisy ).

     .        3. Please ensure with source, for example If the source is inputting a strange Vsync timings then this timing and that will be reflected through the entire path. (Hsync and Vsync are encoded in the same symbol in the input video stream.  Therefore they should be whatever the source is outputting).

Note:  

H & V Sync timings are all based on the VESA, SMPTE or CEA standards depending on the resolution. So the respective resolution timing details we can get it from standards specification.

These details we need to look at the timing specifications from CEA861-E or any other reference document like Video Demystified book ( video-demy5.pdf ) .

Thanks,

Poornima

Dear Poornima-san,

Thank you for your reply and support.

This symptom happen on  EVAL-ADV7182AEBZ with script file ,ADI evaluation board and provided software.

Therefore we think that  the crystal frequency ,power supply filter and register setting are no problem.

We will check to happen dependent on input source.

We have one more question.

Are there posibility that H/Vsync happen synchronization error change  by register setting timing?

For example, input signale then setting resiter. Setting resiter then input signal.

 At writing to the script file, the symptom is chanded normal or abnormal behavior (it is dependent on writing script file timing)

Thanks and Best regards

Isshin Kida

Hi IsshinKida San,

       As per your comment, Issue is still exist even when you do not repeat the step 5 and step 6 continuously. Is my understanding correct?

      The reason i told too don't repeat 'Step 5 and 6' because once we run the script the register configuration remain persist until we power off the board.

 Thanks,

 Poornima

Dear Poornima-san,

Yes,your undestanding is correct.

As result, this issue is dependent on reading "Script file" timing.

But we don't know which registers affect it.

Please advise us which register might be related with this issue if possible.

Thanks and Best regards

Isshin Kida

Hi,

   I don't think the register will affect this abnormal scenario.

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

Thanks,

Poornima

Dear  Poornima-san,

Thank you for your reply.

We tried the different PCBA (by ourselves design) with ADV7182A.

It also happen same symptom.

Please tell us about evaluation schematics "adv7182a-adv7280a-32ebz-sch_a.pdf" around X'tal "ABM8AIG-28.63636MHz-12-2Z-T3"

We think that "-12" of "ABM8AIG-28.63636MHz-12-2Z-T3"  means "Load Capacitance (pF)" on the datasheet

(ABM8AIG-1775167.pdf)

But there is 20pF "Load Capacitance (pF)"  on Evalution board schematics.

(1) Is "Load Capacitance (pF)" around X'tal schematics corret?

(2) Is this X'tal of "Load Capacitance (pF)"  related with this symptom?

Thanks and Best regards

Isshin Kida