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msp430 F2013/ FG4618 I2C junk data buffered

Krishna Thallapaka
Intellectual 770 points

Hello,

 

I wrote :

host_data = UCB0RXBUF at the rcv'r (FG4618 slave).

The variables on both sides behave erratic. What causes these values to change so? They do so even during no data-sent from F2013( t x 'r ).

Should the buffer be flushed every time?

 

Krishna.

 

  • 0
    Expert 1170 points

    Hi,

    sounds like there is a floating input....

    There are no pull-up resistors on the MSP-EXP430FG4618 EVM board. If you don't enable the MSP430 internal pull-up resistors you may see problems.

    For I2C communication you need for the SCL as well as for the SDA line a pull-up resistor. Note that SCL and SDA terminals are open drain I/Os !!!

    Regards

  • 0 in reply to Voyager
    Intellectual 770 points

    Thank you.

    I'm using F2013/ FG4618 Exp Board.

    The internal pull-ups have been enabled for F2013.  As with 430x4xx series, PxREN resistor enable registers are only available in F47x3/4 and F471xx devices.

    Krishna.

  • 0 in reply to Krishna Thallapaka
    Expert 1170 points

    Hi,

    having the 'F2013's pull-ups enabled should be sufficient. There is a connector on the F2013/FG4618 Exp Board that allows to open the I2C connection between the two chips. Are the two jumpers for the SDA and SCL wire put on the connector?

    Regards.

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