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FPD-Link III DS90UB92x

Thomas Feller
Prodigy 200 points

Hi,

We use the SerDes DS90UB925/DS90UB926.

system description: 18Bit mode, 4 IO's, I2C, I2S

I am searching a solution to detect a Link loss between the SerDes.I know there is a register on the serializer with this information, but we don't want that we must polling this register, we need an interrupt for this. We want have also a detection when the deserializer was removed

Witch state does have the IO's (925 & 926) after switching on the power, but before the configuration will be done with the i2c?

In witch state does go the IO's of the Serializer, when the link to the Deserializer get lost?

Best regards

Thomas

  • 0
    TI__Genius 14015 points

    Hi Thomas,

    When the devices are initially powered, assuming the Mode pin is configured for 18-bit mode, the GPIO's will be high impedance. GPIO's must be configured and enabled through register.

    If configured for GPIO use, the outputs will go high impedance if lock is lost. If both units remain powered and the register settings stay the same, the output would be valid again when lock is restored. If either unit loses power, they would need to be reconfigured for GPIO use before the signal would propagate. 

    I hope this helps. Let me know if you have any more questions.

    Thanks!
    Jason

  • 0 in reply to Jason Blackman
    Prodigy 200 points

    Hi Jason,

    just to assure, that I have understand it correctly:

    the SerDes are confugured as 18-bit Mode, Pin 43 of DS90UB925 is configured as an GPO with value true, then an Lock on Pin 32 of the DS90UB926 appears for a short time ==> the GPO on DS90UB925 felt in high impedance (tri-state) also for this short time and goes back to the configured value.

    Is this correct ?

    Thank you versy much.

    Best regards

    Thomas

     

  • 0 in reply to Thomas Feller
    TI__Genius 14015 points

    Hi Thomas,

    Not quite. The behavior you described is how the GPIO pins (GPIO1-4) would work if configured as output with remote enable. The corresponding GPIO pin on the 926 would have to be programmed as an input.

    The GPO pins (GPO_REG4-8) can have their values set by I2C, either locally or remotely. Once the value is set, it will remain as long as the settings stay the same. Lock status does not affect this, but a power reset of the 925 would erase the settings.

    I hope this clears things up. Let me know if you have any more questions.

    Thanks!
    Jason