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DS90UB926Q-Q1: Is it possible to read GPIO2 state?

Oliver Nittka
Prodigy 20 points
Part Number: DS90UB926Q-Q1
Other Parts Discussed in Thread: DS90UB948-Q1, , DS90UB925Q-Q1, DS90UB947-Q1

Tool/software:

Hello all,

I would like to be able to read the state of GPIO2 when configured as input in GPIO mode (see below on why I need to).
I can do the same e.g. on a DS90UB948-Q1 by reading from Register 0x6E (Bit 2), but the data sheet of the DS90UB926Q-Q1 doesn't say anything about reading the current state.

Background:

I'm working on a test bench where the DS90UB926Q-Q1 is part of the unit under test. I need to read a (very slow) digital signal that is input to the DS90UB926Q-Q1 on GPIO2.

Usually, I would configure GPIO as back channel and measure the signal on the respective pin on the serializer. However, the DS90UB925Q-Q1 resides in a third-party-device (BasicCON4121 by Göpel) where I don't have access to that pin (the device was designed to always use the ROUT8 function of that pin).

On a similar Test bench, where a combination of DS90UB948-Q1 / DS90UB947-Q1 is used, I can just configure the pin as GPIO Input via Register 0x1e and read the current state of the pin via register 0x6e. However, for the DS90UB926Q-Q1, there is nothing mentioned in the data sheet.

Does anybody know if there is any way to accomplish that?

Thank you very much in advance!
Oliver Nittka

  • 0
    TI__Mastermind 35095 points

    Hi Oliver,

    The UB926 does not have the option to read the input state of the GPIO. I cannot confirm whether the GPI Pin status register was included in the UB926 so you can see if that works but it will be at your own discretion.

    Best,

    Jack

  • 0 in reply to Jack Scherlag
    Prodigy 20 points

    Hi Jack,

    thank you very much for your answer!
    I'm not sure I understand what you mean by "GPI Pin status register". I couldn't find anything in the datasheet or via google. Is there any common register description across the DS90UB-Series somewhere that I couldn't find? Or is this something different?

    Thanks again!
    Oliver

  • +1 in reply to Oliver Nittka
    TI__Mastermind 35095 points

    Hi Oliver,

    The GPI Pin status register is register 0x6E. GPIO2 is bit 2. This register is shown in the 924 and 928 datasheet.

    Best,

    Jack

  • 0 in reply to Jack Scherlag
    Prodigy 20 points

    OK, now I understand, thanks a lot!
    Unfortunately, the Bit doesn't seem to change when the Signal on GPIO2 changes.

    A side note for future readers: I cannot be absolutely sure because I cannot measure within the UUT, but I have no reason to assume the UUT is defective, so the GPIO should toggle at some point, but Bit 2 in register 0x6e always stays 0.

    Thanks agaein!
    Oliver