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OPT4001DNPQ1EVM: OPT4001DNPQ1EVM: Multiple Data Logging

Jaewon Park
Prodigy 30 points

Part Number: OPT4001DNPQ1EVM
Other Parts Discussed in Thread: OPT4001

Hello TI Suppor Tema,
I am using OPT4001DNPQ1EVM GUI and export output data by CSV file.

Subject: Questions Regarding Simultaneous Logging with Two OPT4001 EVMs and Time Synchronization

I am attempting to compare light measurement data by logging data simultaneously from two OPT4001 EVM boards, each connected to a separate laptop. However, I am facing limitations related to time synchronization and EVM connectivity. My questions are as follows:

1. CSV Time Axis Issue and Absolute Time Synchronization

When exporting data to a CSV file from the OPT4001 EVM GUI, the time column is fixed to a value such as 1.77E+09 and does not change meaningfully over time.
Because of this, it is impossible to compare measurements taken simultaneously on two different laptops.

Question 1:
Is it possible to modify the Python code used for CSV export so that the time column is replaced with the PC’s absolute system time (for example, 07:08:36)?

My intention is to synchronize the system clocks of the two laptops, so that absolute timestamps can be used to compare measurements taken at the same real-world time.

2. Connecting Two OPT4001 EVMs to a Single GUI

I understand that when two OPT4001 EVM boards are connected to a single laptop, the EVM Selector window requires selecting only one EVM, making it impossible to operate both simultaneously.

Question 2:
Is it correct that two OPT4001 EVM boards cannot be connected and logged simultaneously within a single GUI instance?

3. Simultaneous Logging via I2C Wiring Between Two EVMs

I have seen references suggesting that it is possible to connect the I2C lines of two OPT4001 EVMs using jumper wires and perform simultaneous logging.

Question 3:
In this configuration:

  • Do all 8 pins need to be connected via jumper wires?
  • Is it correct to set the I2C address differently (e.g., one ADDR pin tied to GND and the other to VDD)?

3-1. Nature of “Simultaneous” Logging

Question 3-1:
If the I2C lines are shared in this way, does the system truly perform simultaneous logging,
or is it more accurate to describe this as sequential (interleaved) logging
(e.g., Sensor 1 → Sensor 2 → Sensor 1 → Sensor 2)?

From my understanding of I2C operation, it seems more likely that the data acquisition is time-multiplexed rather than strictly simultaneous, and I would like to confirm whether this assumption is correct.

Thank you in advance for your clarification and technical guidance.

Jaewon Park.

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  • 0
    TI__Expert 8210 points

    Hello Jaewon, 

    editing the csv export code should be possible as long as you can access system clock through the libraries that come with the GUI executable. If not then I think you may have to get GUI script running in a different environment to be able to add additional libraries if necessary. 

    You will not be able to access multiple sensors a single GUI at the same time without significantly modifying the current code. However it is possible to run 2 EVMs in 2 different GUI windows on the same computer. 

    It is sequential logging. 

    Thank you, 

    Joseph Scherphorn