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DS90UB960-Q1: Dual I2C Ports Effective rate

qihang zhang1
Prodigy 20 points
Part Number: DS90UB960-Q1

Hi all,

From the datasheet and the application document I2C Communication Over FPD-Link III with Bidirectional Control Channel, I can easily calculate I2C effective rate of DS90UB960.

For example, my local host i2c rate is 1MHz, remote i2c rate is 400KHz.

Effective rate = 9bit / (9us + 22.5us + 1us + 9us) =  219.5kbit/s

But there is a question, if I use dual I2C ports with the same configuration. is the effective rate (219.5kbit/s)  shared by two I2C ports or per I2C port can supports the effective rate(219.5kbit/s)?

  • +1
    TI__Mastermind 28620 points

    Hi Qihang,

    The effective rate will not be shared by the two I2C ports.

    The DS90UB960 has two I2C ports. And you can map each I2C port to an RX port on the DES (See register 0x0C in the UB960 datasheet). Two separate I2C ports cannot be mapped to the same RX port. The effective rate between the DES and one of the SER will be based on 4 factors:

    1. The local host's I2C rate
    2. The remote I2C rate at the SER.
    3. FC Delay
    4. BCC Delay

    You can assume that the FC Delay and BCC Delay are constants, so the only thing affecting your effective bit rate will be the local host's and remote device's I2C rate.

    Best,

    Justin Phan 

  • 0
    Prodigy 20 points

    Hi Justin

    Thanks for your answer. It's really resovled my issue.

    Best,

    Qihang