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DS90UB954-Q1: About CSI-2 waveform timing

Masanori Okano
Prodigy 230 points

Part Number: DS90UB954-Q1

Hi team,

We use DS90UB954 for our products.
We have two types of products with DS90UB933 as evaluation equipment.
Both are 8-bit YUV422 and send BT-601 data, but with different image sizes and PCLKs.
We observed the CSI waveforms and found that the output was different.
Is it possible to change the CSI waveform of product B to the CSI waveform of product A by changing the register settings of 933 or 954?

Or is this difference due to Serdes and cannot be changed by register setting?

2061.Question.pdf

Best regards.

  • 0
    TI__Guru** 115680 points

    Hello Masanori,

    it is not possible to change the CSI wave form. Our device just outputs what it is getting at it's input.

  • 0 in reply to Hamzeh Jaradat
    Prodigy 230 points

    Hi, Hamzeh

    Thank you for your answer. I understand.
    What additional information can you provide about CSI?

    The attached waveforms are observed output waveforms near the deserializer.

    Q.pdf

    Question No. 1
    There is a significant overshoot when transitioning from LP to HS.
    What is the cause?

    This overshoot is not observed if we look at the differential signal, because the same waveforms are generated on the positive and negative sides.
    Is this waveform NG?

    Question No. 2
    When shifting from HS to LP, there is a large overshoot.
    We judge it as NG because it exceeds 1.3V compared to the standard 1.1V to 1.3V.
    What is the cause?
    Also, is there a solution?

    Question No. 3
    When the clock transitions from HS to LP, the data signal drops.
    Is this a problem?
    Is this waveform NG?

    Best regards.

  • 0 in reply to Masanori Okano
    TI__Guru** 115680 points

    Hello Masanori,

    if you run the Pattern generator from the DES and/or from the SER, do you see the exact same behaviour?

    Also, please double check the power-supply levels at all DES power pins and make sure these are compliant with the datasheet.

    Also please measure the noise level and compare with datasheet specs.

  • 0 in reply to Hamzeh Jaradat
    Prodigy 230 points

    Hi, Hamzeh

    Thank you for your prompt reply.
    I will follow your advice and check it out.

    Best regards.