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OPT3001EVM: EVM is reading 0 LUX incorrectly.

Lauren Mayfield
Expert 6910 points
Part Number: OPT3001EVM
Other Parts Discussed in Thread: OPT3001

Hi team,

I am posting this question on behalf of my customer.

 

"After assembling everything and loading the software I turned on the system and was surprised to learn that the illumination in my cubicle is 0 LUX!

 

Here is the screen from my PC after repeatedly clicking Read Reg x00: (Power was on, as verified by two green LEDs on middle hardware.)

 

 

Here is what the Read All produced for a register map:

 

 

The very bottom of the register map had R54 = 49 and R30 = 01.


What could be causing this incorrect reading?"

Thanks!
Lauren

  • 0
    TI__Prodigy 170 points

    Hi Lauren,

    I made my set-up similar to yours and the software set-up seems to work fine. When I disconnected the USB cable slightly, so that the green lights were still on, I encountered a problem similar to yours.

    Once I plugged the device further into the port it worked again. I recommend you make sure your device is properly plugged into your port and your USB cable (if using one) functions properly. I also recommend plugging your device into another port to make sure it isn’t the ports issue. I also noticed that your MEAS 4 and 5 buttons weren’t on from your last image. Assuming that your device is working properly, you should be able to click that button and both lights will turn on, allowing you to take measurements. If neither of the two issues I mentioned are the problem, please let me know and I’ll get back to you as soon as I can.

    Best,

    John M.

  • 0 in reply to John Morin1
    TI__Expert 6910 points
    Hi John,

    Thank you for your quick response and your suggestions. Unfortunately, those were attempted and did not work.

    Do you have more suggestions?

    Thank you,
    Lauren
  • 0 in reply to Lauren Mayfield
    TI__Prodigy 170 points
    Hi Lauren,

    Could you send a picture of your EVM's set-up?
    Can you also confirm that you can read and write from the configuration register (address 0x01)? We'd like to confirm that the I2C is working and that it is only the result register (0x00) that is reading all 0s.

    Please perform the following process:
    1) EVM unplugged and GUI closed => plug in EVM and launch GUI
    2) Read from register 0x01
    3) Write a different value to 0x01
    4) Read back the same register (0x01) to confirm it has changed

    You can perform steps 2-4 on the first tab of the GUI. Please let me know your results and we'll continue forwards from there.

    Best,
    John M.
  • 0 in reply to John Morin1
    TI__Expert 6910 points

    Hi John,

    "I tried your write then read experiment and did not achieve the expected results. After repeatedly writing 0x7FF7 to register 1, reads consistently show 0x7F97. After repeatedly writing 0x3380 to register 1, reads consistently show 0x3080.

    Apparently the device recognizes that I am writing something to its register, but it has a mind of its own."

    Attached is the set-up picture.

  • 0 in reply to Lauren Mayfield
    TI__Mastermind 25815 points
    Thanks Lauren,

    We will check into this further tomorrow. I have not have a chance to check this with the value you used, but some of the config registers are read only. Did you confirm that you are only writing to the R/W bits of the register? Because this could result in the writes differing from the read values. We will also check into this tomorrow, but wanted to post this now to keep things moving quicker in case that is an issue here.

    Best,

    Alex
  • 0 in reply to Alex Bhandari-Young
    TI__Expert 6910 points

    Thanks Alex for your rseponse, he's now verified that each write-able bit can be changed and read back successfully.

    What are the next steps to try?

  • 0 in reply to Lauren Mayfield
    TI__Prodigy 170 points
    Hi Lauren,

    Could you send us a picture of the front (other side) of the OPT3001 to make sure it is unobstructed and properly connected. The sensor is on the other side of the board in the image you sent. Are you sure that you are measuring with the sensor side facing up?

    Also, could you verify if you can run continuously by clicking the "run continuously" switch? This will cause the graph and lux reading to continuously update. Or does this not work and you have to click “read register” each time to get a value back?

    If we cannot find a possible solution from this response we’ll email you with our options moving forwards.

    Best,
    John M.
  • 0 in reply to John Morin1
    TI__Prodigy 170 points
    Also, I forgot to ask if you could set the low limit register (low limit mantissa) to anything but 0 and then perform the "run continuously" test to see if the low limit flag (FL) gets triggered.
  • 0 in reply to John Morin1
    TI__Expert 6910 points
    Hi John,

    Here is response

    "I had never tried the “Run continuously” switch, but when I clicked that things started working.

    When I then turned off the switch “Read Reg x00” started giving me non-zero answers."

    Looks like things are working now. Thank you very much for your help!