SPIO-4: Can't read ph or temperature from LMP91200EVAL Board

Hi Jordan,

Have you ensured that the jumpers are set to the correct position, as described in the User's Guide?

Could you please provide a screen shot of the GUI when you run both of these GUI configurations?

Best Regards,

Dan

Hi Jordan,

There is actually an EVM "unboxing" video for the LMP91200 that is very useful for getting started. Hopefully, this will address the issue that your are having.

Please keep in mind that this demo used an older version of Windows (looks like XP), so some of the instructions may be different when using Windows 10.

Best Regards,

Dan

Hi Dan,

I believe all of the jumpers are shorted correctly. However, there are three that don't have the individual pins numbered so I wanted to double check with if these are configured correctly:

JP1: shorted VDD-EXT to VDD_DUT (1-2 shorted)

JP3: shorted REF to VREF_ADC (1-2 shorted)

JP7: shorted DIAG-EXT1 to SDO_DIAG_DUT (2-3 shorted)

I have watched the video and I have everything setup as he does except for the temperature sensor. I also can't seem to find the pH kit he has in the video on TI's website.

I have attached screenshots of the GUI while running each configuration (before clicking run and the error message I receive). I have also attached a screenshot of the configuration for the custom sensor I am using. I am not exactly sure if the Max_Probe_Resistance or the Int_Temp_Sensor are correct because the documentation I have on the pH sensor does not have this information, but I have tried selecting both types of temperature sensors and a variety of values for the max probe resistance and I always get the same errors. I have also tried selecting many of the given pH sensors in the software and also receive the same error messages. Even if these are not correct shouldn't I at least be getting some reading from the pH sensor even if it is not accurate?

Jordan

Hi Jordan,

JP1, JP3 and JP7 look correct, according to the user's guide.

I would suggest taking a voltage measurement at vout on the LMP91200 evaluation board while it is connected to the SPIO-4. Is there any voltage present? If so, does it change while the pH sensor is exposed to a different pH substance?

Best Regards,

Dan

Dan,

We tried measuring the voltage at vout while the pH sensor was exposed to 2 different fluids that had a pH of 4 and 5 (which was determined using the same pH sensor connected to our benchtop pH meter), and the results were very inconsistent. The voltage measured while having the pH sensor in the fluid with a pH of 4 would read about 50 mV one minute, then 150 mV a few minutes later, and then 90 mV later. It was hard to determine if changing between fluids had an impact on the voltage because of how much the voltage varied while keeping it in just one fluid. The benchtop meter however gave very consistent readings, so it seems like something may be wrong with the LMP91200 evaluation board.

Even though these readings are so inconsistent, I still don't understand why the software can not read any data from the board even if it is not at all accurate. With voltages between 50 and 150 mV we should be seeing pH readings between 1 and 3 in the software, but instead we just get the errors in the screenshot in my previous post. Could this be an issue with running it on Windows 10?

Jordan

Hi Jordan,

Thanks for taking those measurements. When you connect only the SPIO-4 EVM to your computer (with LMP91200 EVM not attached), how is it recognized by Windows10? This is what my computer shows

Best Regards,

Dan

Dan,

For some reason we could not get our computer running Windows 10 to recognize the SPIO-4 board today, so we switched to a computer with Windows 7 and are still having the exact same issues.

Here is how the computer running Windows 7 recognizes it:

It looks like everything is the same except the file version.

Jordan

Hi Jordan,

Have you tried selecting a predefined sensor, disconnecting the pH sensor and then taking a reading? Are you getting the same errors?

When you change the jumpers on the LMP91200 EVM, are you losing connectivity to the device via the GUI? Do you see any LEDs on the SPIO-4 board change when the jumpers (especially JP1 and JP3) are changed? On the SPIO-4, D8 and D7 should be illuminated if the jumpers are configure correctly on the LMP91200 EVM.

Best Regards,

Dan

Dan,

I have tried using many of the predefined sensors with and without the pH sensor connected and receive the same errors.

I tried changing all of the jumper configurations around and all of the LEDs (D5, D6, D7, D8, D10, and D11) stayed on the entire time, even when some jumpers were disconnected. The GUI also never indicated that it lost connectivity at any point. One thing I notice is that the LED D6 is dimmer than the rest of the LEDs.

Jordan

Dan,

I see, thanks for the information. We will look into using stand alone mode with the EVM.

Also one last question: Do you know if there are any Matlab drivers to use the SPIO-4 Board with Matlab?

Thanks for your help,

Jordan

Dan,

I see, thanks for the information. We will look into using stand alone mode to use the EVM.

Also one last question: Are there any Matlab drivers to use the SPIO-4 with Matlab?

Thanks for your help,

Jordan

Will do, thanks for all your help Dan.

Jordan