• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 718 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.

DS90UB902Q-Q1: LOCK with a DS92LX1621 Serializer Affected by I2C M/S Selection of Deserializer

Tom Sudol
Prodigy 40 points
Part Number: DS90UB902Q-Q1
Other Parts Discussed in Thread: DS92LX1621

We are attempting to use a DS90UB902Q deserializer in some test hardware receiving data from the DS92LX1621 part.  It is an imaging/camera application with the DS90UB902Q receiving image data from a remote DS92LX1621 and I2C communication occurring through the parts with the DS90UB902Q configured as a slave and the DS92LX1621 as a master.  We are having difficulties reliably achieving LOCK of the two parts on power up.  What we have observed, however, is the LOCK is reliably established when the deserializer is switched from SLAVE to MASTER mode.  This is while no I2C transactions are actually occurring (no changes to I2C registers taking place anywhere in the system).

Anyone have any ideas why this is occurring?  We are hoping it's explanation might be a clue to our difficulty of achieving LOCK while in the needed SLAVE/MASTER configuration.

  • 0
    TI__Genius 10475 points
    Hello,
    What kind of behavior are you seeing on LOCK pin when you see the issue? What I2C mode are you using and which side is your controller located?
    The datasheet provides details on the I2C modes and when to use which mode. Please verify the MODE pin is set accordingly.
  • 0 in reply to Palaniappan Manickam
    Prodigy 40 points
    In the final application we need the DS90UB902Q configured as an I2C slave (MODE pin is pulled high, the device receives I2C communication from a local master) and the DS92LX1621 configured as an I2C master (M/S pin is pulled low, the device drives the I2C bus locally). When in this mode, however, the devices typically do not sync up after power-up and the LOCK pin of the DS90UB902Q toggles between 1 and 0. Image image data can not be successfully pushed through the link when in this state. Through many resets and power cycles I am on occasion able to get them to sync, in which case they seem to reliably stay sync'd and able to transmit image data and I2C communication until powered down. When the MODE pin of the DS90UB902Q is driven low, however, the LOCK pin of the DS90UB902Q immediately goes high and I am able to transmit image data (though I am not able to send I2C communication, obviously).
  • 0 in reply to Tom Sudol
    TI__Genius 10475 points
    Hello,
    We somehow missed to follow up on this one. Let us know if this is still a problem you're facing so we can provide some help.
    The I2C communication cannot start reliably until LOCK is established.
    For debugging I2C issues, confirm the I2C configuration registers, IDx and address are set properly and proper SDA/SCL pullups are there.
    If LOCK is toggling you can look at the quality of PCLK input and power supply noise. Also ensure the power supplies and PDB are at proper levels and sequenced properly.