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DS90UB925Q-Q1: DS90UB925/926 Repeater Issues

Richard Elmquist
Mastermind 45250 points
Part Number: DS90UB925Q-Q1

My customer is having issue in setting up a repeater application with the DS90UB925/926. His configuration is as follows:

926-->925-->926-->925

He is trying to send commands to the last chip and is having issue. I have checked and all of the chips have a different address set so this is not the issue. I also questioned the repeater configuration, but it seems that if you set the registers properly this should not be an issue. He has done the following:

In addition I have set the 1st and 2nd DS90UB925 to ‘I2C_PASS_THROUGH’ by setting Bit 3 in the CFG0R Register. I also confirmed that the 1st DS90UB926 and the 2nd DS90UB925 are set to ‘Repeater’ mode.

He also made the following comments:

I realize that I have to set registers sequentially to access.  So what I have tried so far is the following (see Register overview tab): 

In order to address the 2nd DS90UB925:

I set the SIDR Register (0x07) and the SAIDR Register (0x08) of the 1st DS90UB925 to ‘0x32’, which is the ID of the 2nd DS90UB925 preset by the resistors R3/R4.

After that I can access all the registers of the 2nd DS90UB925.

This works fine. 

In order to address the 2nd DS90UB926:

I set  the SIDR Register (0x07) and the SAIDR Register (0x08) of the 1st DS90UB925 to ‘0x60’, which is the ID of the 2nd DS90UB926 preset by the resistors R3/R4).

After that I can access all the registers of the 2nd DS90UB926.

This works fine. 

In order to address a slave device on the display board (e.g. touch controller):

First I set the the SIDR Register (0x07) and the SAIDR Register (0x08) of the 1st  DS90UB925 to ‘0x32’ , which is the ID of the 2nd DS90UB925 preset by the resistors R3/R4.

Next I set the SIDR Register (0x07) and the SAIDR Register (0x08) of the 2nd DS90UB925 to ID of the touch controller.

There are no I2C signals on the SCL or SDA line on the 2nd DS90UB926 device

 In addition I have set the 1st and 2nd DS90UB925 to ‘I2C_PASS_THROUGH’ by setting Bit 3 in the CFG0R Register. I also confirmed that the 1st DS90UB926 and the 2nd DS90UB925 are set to ‘Repeater’ mode.

Do you know why he is not able to send I2C signals directly to the second 925? What might he be doing wrong that is causing the issue?

Please let me know if you need additional information from the customer.

Thanks for your help with this!

Richard Elmquist

  • 0
    TI__Genius 10475 points
    Hello,

    This has been assigned for Apps to look at. Do you know if there is a FAE involved in supporting this issue?
  • 0 in reply to Palaniappan Manickam
    TI__Mastermind 45250 points

    Palaniappan,

    Thanks for your help!

    There is no FAE assigned to this case. I am working this with the customer.

    Please let me know if you have any idea what might be happening with this issue. Let me know if you need further information from the customer.

    Richard Elmquist

  • 0 in reply to Richard Elmquist
    TI__Mastermind 45250 points

    Palaniappan,

    Have you been able to find any issues with the customer's application?

    Do you have further questions for the customer?

    Thanks for your help with this!

    Richard Elmquist

  • 0 in reply to Richard Elmquist
    TI__Expert 4210 points

    Hi Richard,

    Can your please provide a register dump of each SER and DES? This will help in the debug?

  • 0 in reply to Darryl Jeong
    TI__Mastermind 45250 points

    Darryl,

    I will try and get the information from the customer, but not all of the devices seem to be communicating on the bus. If this is the case, how will he be able to actually dump the registers of the down-stream devices? I am not sure that he will be able to send resister dumps for these devices. If he cannot dump the registers what further information can he send to you so that you can try and diagnose the problem.

    Can you verify if the configuration he is using is correct? Does he have the components installed as necessary for a repeating application? The configuration seems to me to be correct, but I am not sure for this type application.

    Can you try and answer these questions today so that I can contact the customer? It has been a week and I have not been able to offer him any answers to his questions.

    Thanks for your help with this!

    Richard Elmquist

  • 0 in reply to Richard Elmquist
    TI__Mastermind 45250 points

    Darryl,

    Were you able to look at my previous response? I do not know how he can dump the register contents when he cannot communicate with the components. Please let me know if the configuration that I explained in the forum post is conducive to being used as a repeater.

    Thanks for your help with this!

    Richard Elmquist

  • 0 in reply to Richard Elmquist
    TI__Expert 4210 points

    Hi Richard,

    I replied to your email.

    In addition to my email response when I asked about LOCK, let me clarify... use a scope and make sure LOCK is a constant logic HIGH and not going LOW every so often.

  • 0 in reply to Darryl Jeong
    TI__Mastermind 45250 points

    Darryl,

    The customer stated that he has a constant "Lock" signal on the first and second serdes pair. He just cannot get the "lock" signal from the other IC in the signal chain. He will try and get some register dumps as soon as possible, but he has listed the registers that were changed from the default settings. I am going to send a document to your regular email that details the setup and the registers settings that he is trying to change.

    Thanks for your help with this!

    Richard Elmquist