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LP5024EVM: Establishing an I2C Connection

Kathleen Salter
Prodigy 190 points
Part Number: LP5024EVM
Other Parts Discussed in Thread: USB2ANY, , MSP430G2553, TMP112, LP5024

Hi,

I am trying to set up I2C communication with the LP5024EVM using an MSP430G2553. I have already checked that the board is working through the USB2ANY and am now trying to communicate with it with my MSP430. I have gotten communication running with another peripheral (TMP112) so I don't believe the problem is on the MSP430's side. 

Are there any jumpers that need to be changed in order to use the EVM with I2C? I have an external 5V power supply and have noted all my current jumper connections below in red:

My specific issue that I am currently encountering is that when I don't have the EVM on the I2C lines, there is no problem. When I connect the SCL and SDA lines of the EVM to the rest of the system, the line is held high and all communication stops.

Thanks for your help,

Kathleen

  • 0
    TI__Genius 12915 points

    Hi Kathleen,

    I think the jumper setting is OK. You mean that SCL/SDA is staying high and have no signal after connecting to EVM? Or the slave have no feedback to 430. Could you help to capture some plots while sending commands?

  • 0 in reply to Hardy Wu
    TI__Prodigy 190 points

    Hi Hardy,

    This is a scope capture of my I2C connection without the LP5024EVM attached:

    This is a diagram of how my circuit looks when this capture was taken:

    When I attach the LP5024EVM, I wire the SDA/SCL pins directly below the 10k resistors on the same line as TMP112's SDA and P1.7 and the same line as TMP112's SCL and P1.6.

    The following is what my waveforms look like running the same code and using the same capture settings, the only difference is that the LP5024 has been added to the SDA and SCL lines:

    Thanks,

    Kathleen

  • 0 in reply to Kathleen Salter
    TI__Genius 12915 points

    Hi Kathleen,

    Could you help to try removing J2 jumper in below red rectangle (should be left down of the EVM). It pull up SDA/SCL to board power supply with 4.7kohm, while you already have one pull up connection. And after that you need to connect EN (J6) to the power supply to enable IC.