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How to connect FMC to I2C

Former Member

Dear All,
Sorry if I am requesting for already present topic, but so far I have not found anything that relevant.
I need to provide I2C lines through FMC connectors to an EEPROM and a clock generator.
As per my little knowledge FMC produces LVDS output(or inputs) while I2C requires CMOS level which are not compatible. Thus a pair of LVDS lines are required for each of the SDA and SCL lines.
However in most of the references I found only one LVDS line supporting SDA (and another LVDS line for SCL). I am finding it incomprehensible as how a single line is sufficient for SDA or SCL.
Anybody kindly throw some light into this issue.

  • 0

    Hi,
    Thanks for your information. But it is not clear to me as how it works.
    As per my knowledge LVDS is a current carrying differential signal that needs to be translated to voltage levels at its reception/terminating point. Specification tells LVDS and its LVC,LVPECL etc family carries differential current with around 350mV between the two lines. Thereafter at the terminating point the terminating resistance converts the two differentiated signals to a single undifferentiated output (in volts). This output signal is in order of a few volts(mostly in 3 to 5 V range) and is CMOS compatible.
    I am using Zynq 7000. Is it able to produce sufficient voltage at its output to drive I2C lines?
    Regards,
    Debasish

  • 0 in reply to Former Member

    I2C is open drain. Zynq just needs to be able to drive this to low voltage, and yes, it can do that.

     

    Further, the FMC specification has a provision for dedicated I2C pins on the FMC connectors. On ZedBoard, you will find the FMC SDA/SCL I/Os with on-board pull-ups and connected to Bank 13 (Pin R7 for SCL, Pin U7 for SDA).

     

    Bryan