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INA228_237_238EVM: Connected to GUI & Simple Resistor Circuit but can't get readings

Laurence Boss
Prodigy 10 points
Part Number: INA228

Hey TI Forums, I purchased the INA228EVM Current-Sense IC Module to use in a project of mine but I decided to test it before with a very simple resistor circuit:

This circuit is realised in real life as shown in the image below:

  • The twisted red and black wires connect the circuit to a 5VDC Power Supply.
  • The load resistor is 330Ω.
  • The external shunt resistor is 80mΩ, and is connected to the EVM and the Load Current Lines as instructed by the following image from the documentation:

  • VBUS is connected to the same 5VDC from the power supply, and the EVM GND is connected to the power supply GND
  • As can be seen, the EVM is connected via the supplied Sensor Control Board (SCB) to my laptop (using the white USB cable) with all the appropriate drivers installed, and is successfully identified by the official GUI, as shown:

With the 5VDC provided to the circuit, a multimeter measures the expected 1.2mV across the shunt resistor (I_Load = 5V/330Ω = 15.15mA -> V_SHUNT = 80mΩ*15.15mA = 1.2mV). This measurement was made with the probes directly across the resistor and by placing the probes across the R1 solder pads to ensure the shunt voltage was being received by the PCB.

The settings for the EVM are set as shown here:

The hardware switches on the board (SW1: SDA, SW0: SDA) match the switch settings shown in the image.

The trouble is that even though everything is receiving power (both boards LEDs are on), the EVM is successfully connected to the GUI, and the correct voltage is measured across the shunt resistor meaning that the correct current is flowing through it, the GUI still returns no reading of V_SHUNT or CURRENT, as the result page here shows:

I am left a bit confused and not sure what to do, so I'm hoping someone here might be able to offer some help and get this EVM working.

Thanks in advance,

Laurence

  • 0
    TI__Mastermind 26245 points

    Hello Laurence,

    Thank you for using the TI forum. Can you also send me a screenshot of the register map page so that I can see the device settings/status? Also, do you have this issue when using other address configurations? Could you try setting both to GND and see if the problem still happens? (Though I doubt this will help, but it's good to check.)

  • 0 in reply to Mitch M
    Prodigy 10 points

    Hi Mitch,

    Thanks a ton for getting back to me. Please find a screenshot of the register map page below:

    It is very strange, every combination of address configuration allows the EVM to connect to the GUI (still not getting any V_SHUNT or CURRENT readings though), but if I try SW1: GND, SW0: GND, the SCB + EVM refuses to connect properly, and I get this error:

    Don't know if that's relevant to the problem but very weird.

  • 0 in reply to Laurence Boss
    TI__Mastermind 26245 points

    Hello Laurence,

    There are definitely some odd things going on.  For example, the power register seems to also be showing the device ID....  also the temperature register looks wrong. If you try to change a register setting in the drop down, does it let you? For example, does it let you increase the conversion time, or does it set it right back?

    When you set the switches to GND and GND, did you try to power cycle or reset the board? Sometimes if you click the reset button too fast it may not reset properly, so you could also try pressing that button longer.  Also, you may need to refresh the GUI and/or try another USB port.  

    One other good check would be to see if it lets you update the firmware after it connects (from file -> program device). This may also fix the issue. (make sure you are using the latest GUI, which currently is version 2.0.0.). This will also only work if you have installed the driver (usually done as an administrator is required).

  • 0 in reply to Mitch M
    Prodigy 10 points

    Hi Mitch,

    That is weird about the registers. It does let me change register settings in the drop down menu without being set right back, and one can observe the corresponding bits changing in the registers.

    Unfortunately, when I set the switches to GND and GND, I did try pressing the reset button for longer, refreshing the GUI, and tried 2 other USB ports to no avail. I still receive the same 'Unknown EVM(s) Found!'

    I had also already installed the driver and successfully updated the firmware with the latest GUI (2.0.0), as the image below shows, but sadly the issue persists.

  • 0 in reply to Laurence Boss
    TI__Mastermind 26245 points

    Interesting...  So it seems to be communicating with the device, (when not at GND/GND), but primarily the results registers are not working.... You may have already tried this, but could you double confirm with an external volt meter that there is power on the buss and a voltage drop across the shunt?

  • 0 in reply to Mitch M
    TI__Mastermind 26245 points

    Also, can you try one more test?

    • Power down everything and close the GUI
    • Disconnect the load. (ie, only leave the EVM connected to the SCB
    • Set the hardware switch settings to something that was connecting for you (and/or specifically try GND/GND?)
    • Power up the SCB and EVM
    • Launch the GUI
    • If the GUI connects, go to the plots page and unselect all results except DIETEMP.
    • Press "Collect Data"

    This will help us see if it is working without being connected to your circuit. 

  • 0 in reply to Mitch M
    Prodigy 10 points

    Hey Mitch,

    I measured the Bus Voltage with an external voltmeter and got the expected 5V:

    I did the same with the voltage drop across the shunt and got the expected ~1.2mV:

    I followed your instructions first using hardware switch settings that allowed the device to connect, and the final result for the DIETEMP plot was as shown here:

    An attempt to do this with GND, GND switch settings was also made but the same 'Unknown EVM(s) Found!' error resulted.

    Thanks again for your continuing efforts to help me Mitch.

  • 0 in reply to Laurence Boss
    TI__Mastermind 26245 points

    Hello Laurence,

    Thank you for doing those tests. I am thinking there must be a hardware issue of some kind. I've sent you an E2E friend request so that I can get any needed info to send you a replacement. 

    I'll mark this thread as "TI Thinks Resolved", and then if the new EVM works fine (proving the hardware issue theory), then you can come back here and mark it as "Resolved".