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transfer meaning of I2C Free Data Format

Okayama Gou
Intellectual 930 points
Other Parts Discussed in Thread: TMS320F28035

Dear,

Device: TMS320F28035

I want to use I2C Free Data Format.
Piccolo I2C Module Reference Guide, sprufz9d.pdf, says following in page 17:

the direction of the data must be constant throughout the transfer.

I don't understand well "transfer".
Does the "transfer" have meaning as "from Start bit to Stop bit"?

Thank you and Best regards,
Okayama

 

  • 0
    Intellectual 700 points

    Partially. On writes, the data transfer happens from master device to slave device with only the ACK/NACK bits coming from the slave device.

    On reads, the master device puts out a start bit, writes the address byte and possibly some data bytes depending on the requirements of the slave device (internal register addresses, commands etc); then puts out a Re-Start bit and the slave device takes control of the data line to send data to the master device with the master device doing the ACK/NACK bits.

    Clocking as always is a cooperative effort between the master and slave, the master exerting nominal control but the slave allowed to extend the clock low condition as necessary (and within limits).

    There is a copy of the I2C spec at

    http://www.classic.nxp.com/acrobat_download2/literature/9398/39340011.pdf

    The SMBus spec is also helpful

    http://smbus.org/specs/

     

  • 0 in reply to Chris McDermott
    Intellectual 930 points

    Chris-san,

    Thank you very much for your reply.

    But I'm afraid my question were not good.
    My question are:

    sprufz9d.pdf says,
    the direction of the data must be constant throughout the transfer.

    Is the above meanings following?
    the direction of the data must be constant throughout "from Start bit to Stop bit".
    the direction of the data can not be changed throughout "from Start bit to Stop bit"


    Thank you and Best regards,
    Okayama