• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 33 subscribers
  • Views 186 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DS90UB941AS-Q1: DES_DEV_ID=0

Ryan Wang
Expert 7710 points

Part Number: DS90UB941AS-Q1

Dear expert

My customer system is UB941+UB948 which is already in mass production. 

There is one board which shows very strange problem.

1. Video shown in screen are all good.

2.  UB941 0x6 register DES_DEV_ID=0

3. Access from SoC (at UB941 side) to UB848 registers are all normal

4. UB941 0xA and 0xB CRC error register are all 0

5. SoC (at UB941 side) report lots of CRC error for I2C data from touch screen at UB948 side.

It's very hard to explain.

1. If channel spec cannot meet requirement , why video are all OK.

2. If I2C with BC channel is bad, why UB948 access is all good.

3. Why UB941 DES_DEV_ID is 0?

Could you give me some comment on this issue?

  • 0
    TI__Guru 66870 points

    Hi Ryan, 

    How many total units have been built and tested? Is this one unit in 1k, 10k, 100k, etc?

    How often does this issue happen? x times in X amount of cycles?

    Ryan Wang said:

    4. UB941 0xA and 0xB CRC error register are all 0

    5. SoC (at UB941 side) report lots of CRC error for I2C data from touch screen at UB948 side.

    These two statements seem to contradict one another. Is communication between 941 and 948 successful via I2C?

    Ryan Wang said:
    3. Why UB941 DES_DEV_ID is 0?

    This might indicate that there is something wrong with the back-channel such that the DES_DEV_ID isn't auto-loaded.

    What does register 0xC report?

    Regards, 

    Logan

  • 0 in reply to Logan Cummins
    TI__Expert 7710 points

    Logan,

    This is one unit in more than 50ku.

    For this unit, it happens all the time.

    Logan Cummins said:
    These two statements seem to contradict one another. Is communication between 941 and 948 successful via I2C?

    Yes, it seems very confusing. 

    Communication between UB941 and UB948 via I2C are all OK.

    0xC register is 0x05.

    If you never saw this issue before, I will check it my myself first. Thanks