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OPT3101EVM: OPT3101EVM I2C ERROR

Part Number: OPT3101EVM
Other Parts Discussed in Thread: OPT3101

Hi ..

I have been tested opt3101EVM. 

I connected i2c pin between OPT3101EVM(SDA_S, SLC_S) and my MCU board.

After connection, OPT3101EVM I2C is not working. 

So, I disconnect i2c and test EVM alone. But it's not working.  

I got follow Error message.

"Operation I2C Register Read Failed". 

I thing that connection between EVM and my MUC board is something wrong. 

How can I fixed this problem? 

Thank you

Best Regards

  • Hi Daniel,

    The EVM was working before you connected your MCU, correct? How did you connect your MCU to the EVM? Can you check that nothing as shorted out when you connected your MCU. Also if you can probe on the I2C lines to see if there is activity that would be helpful.

    Best,

    Alex
  • Hi Alex

    Yes, It was working before I connected my MCU.

    I directly connected i2c pins of MCU to the SDA_S and SCL_S pins of EVM.

    I used I2C pins of J17 on EVM.

    And I checked that nothing as shorted out when I connected MCU.

    Now I disconnected EVM and my mcu.

    I'm Testing EVM only. When I start the Latte, there is a error message.

    "Operation I2C Register Read Failed."

    It's not working Latte program.

    So I seem to guess that OPT3101 I2c pins or MSP430 I2C pins are damaged.

    One more question...

    If I connect EVM to my MCU by i2c, I can use i2c pins of EVM, #3, #4 J17?

    Error is...

  • Hi Daniel,

    Based on your log output the I2C between MSP430 and OPT3101 on the EVM is not working. Was the external MCU on a demo board? What external circuitry is on the MCU board? What are the pull up resistors on the MCU board and what voltage do are they pulled up to? If you can provide a schematic that would be best. I can then check if it is okay to connect as you did.

    Best,

    Alex
  • Hi Alex,

    I have found the reason. The SCL_S and SDA_S pins are shorted when I connected external MCU pins by wire.
    Now, OPT3101EVM I2C is working now.

    Another question is about connection between external MCU and OPT3101EVM.
    I'll use EFM32G MCU, want to test i2c with OPT3101EVM before embedded OPT3101 on my board.
    So, I connected i2c pins of EFM32G MCU to J17(SCL_S, SDA_S) of OPT3101EVM.
    There is no pull up registors on EFM32G MCU but I use internal pull up registors in EFM32G gpio peripheral.
    The I2C pins of EFM32G MCU voltage is 3.3V.
    When I test i2c with EFM32G MCU and OPT3101EVM, TI-Latte is not working and EFM32G can't be receive any data from OPT3101EVM.
    I think that there is a problem because two i2c masters are on i2c bus.
    How can I test i2c by EFM32G MCU?
  • Hi Daniel,

    I see you created another thread on this follow up question. Let's close this thread and I will answer your question there.

    Best,

    Alex