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[FAQ] DS90UB941AS-Q1: Access Two Deserializers in Splitter Mode which have the same I2C Address

Part Number: DS90UB941AS-Q1

When DS90UB941AS-Q1 is connected to two remote deserializers in splitter or independent mode which have the same physical I2C address, how can they be accessed independently via I2C?

  • Since DS90UB941AS-Q1 does not have port-specific I2C aliasing for the remote deserializer address, an override of the physical address for the port 0 deserializer is required.

    Step by Step:

    1. Set 0x1E = 0x01 on 941AS to select port 0

    2. Set 0x03 = 0x9A on the 941AS to enable I2C passthrough 

    3. Set 0x00 = "Override Address" on the DES to assign the DES on port 0 to a different physical I2C address. Make sure that bit 0 of the register is set to 1 in order to enable register override of the strapped I2C address 

    4. Set 0x1E = 0x02 on the 941AS to select port 1

    5. Set 0x03 = 0x9A to enable I2C passthrough 

    6. Set 0x01 = 0x01 or 0x03 to return PORT_SEL to default value 

    Now the DES on port 1 can be accessed with the default strapped I2C address and the DES on port 0 can be accessed with the "Override Address" 

    Best Regards,