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FDC1004EVM I2C specification

Takumi Suzuki1
Mastermind 8570 points
Other Parts Discussed in Thread: FDC1004

Hi

I would like to ask you a question about I2C specs of FEC1004EVM.

As you know, we can cut the EVM in 3 parts as below.

 

Between "USB to I2C" part and "FDC1004" part is connected with I2C interface.

My question is what is the maximum distance we can communicate with I2C.

Could you tell me what is the max distance of I2C interface? 

Thank you in advance.

 

  • 0
    TI__Genius 9655 points

    Hi Takumi,

    On the "USB to I2C" peace of EVM there are the pull-up resistors of the I2C, they are 5k each (see schematic of the EVM in the EVM user's guide). When you conect a cable between the "USB to I2C" and FDC1004" pieces of the EVM you have take in account for  the capacitance of the wire.

    Longer is the cable, higher will be the capacitance, it means that you have transmit at lower rate.

    The GUI configures a I2C bus wiht a clock rate of 400kHz, so it means that the load capacitance should be at maximum 100pF. Once you know the capacitance/m of your wire you can make the calculation.

    If you want increase the distance you have to operate to lower clock rate, but this cannot be changed in the  GUI.

    regards,

    Domenico

  • 0 in reply to domenyko
    Mastermind 8570 points

    Domenico-san,

    Thank you very much for your answer.

    I could understand well.

    Best Regards,