DS90UH929-Q1: DS90UH929/928 tentative black screen issue debug

Hi Kazuki,

Kazuki Kuramochi said:

Is there any other problem which case lock loss from the view point of 929 and 928 system?

No, you covered the major cases.

Kazuki Kuramochi said:

What problem will cause lock loss from DES side?

The DES will look for a specific data sequence in the forward channel frame for lock. Any disturbance to this data sequence (for example, loose connection, high jitter, VOD change) could cause lock drop - Further discussion need to be taken offline.  I will reach out to you over email with more details.

Kazuki Kuramochi said:

Is there any way to confirm the correlation between IN_CLK halting and Lock Loss except directly monitoring IN_CLK and LOCK pin as follows.

You can use internal patgen with external timing and internal patgen with internal timing, that way you can isolate whether the issue is due to timing or clk. 

In addition, you can check the following:

• MAP tool result measured from deserializer within ALP. See userguide here: https://www.ti.com/lit/ug/snlu243/snlu243.pdf
• Measure total channel return and insertion loss and check against channel specification
• Measure HDMI CLK jitter and clock stability meets datasheet specification
  • This requires special scope settings to match CDR PLL, see below:

  • To characterize total jitter, TI recommends to measure the TJ@BER with a high speed oscilloscope equipped with a jitter analysis program such as DPOJET. The clock recovery settings used in the DPOJET measurement are designed to match the input PLL characteristic of the serializer device

    - Method = PLL Custom BW

    - PLL Type = Type II

    - Loop BW = 1MHz

    - Damping = 700m

    - Target BER = 1e-10

    - High pass filter: None

    - Low pass filter: None

Kazuki Kuramochi said:

Is there any way to monitor 929's specific bit on 0x0C or 0x5A through GPIO or INTB?

No, but can you provide register dumps from both devices during the error case and during normal operations. Please provide these in text form not as screenshot so that I can compare them.

Regards,
Fadi A.