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PGA309 SENSOREMULATOREVM SensorEmulatorEVM Evaluation Module setup/config

Michael Parrish
Intellectual 425 points
Other Parts Discussed in Thread: SENSOREMULATOREVM, PGA309, PGA309EVM-USB

I recently purchased the SensorEmulatorEVM Evaluation Module.

I also have the  

PGA309 Test Board and USB DAQ Platform set

(2) PGA reference designs PCBA;s constructed.

I'm wishing to set-up the SensorEmulatorEVM to do "what-if's" and aid in the selection of my pressure sensor strain gauge.

The problem that I am having is that the documentation supplied CD with the SensorEmulatorEVM Evaluation Module is showing older "dated" accessories hooked up to the SensorEmulatorEVM Evaluation Module.

On the supplied CD of the (2) PGA reference designs PCBA;s constructed the docs  PGA309 Quick Start_sboa103c.pdf and PGA309 Quick Start_sboa103c.pdf are not referring to the PGA309 Test Board and USB DAQ Platform set.

I presume the older "PGA309 Sensor Interface Board" is equivalent to the "PGA309 Test Board" which I have therefore I can substitute the PGA309 Test Board or one of my (2) PGA reference designs PCBA;s I have constructed as well? 

The instructions as such are not clear to me on hooking up as they are referring to other accessories which I presume were offered in the past.

The Sensor Emulator I won't need to use for temperature simulation, I have my design setup for using the temp sensor internal to the PGA309 so I really just need the Sensor Emulator to provide a zero and span output and then vary it around for my "what-ifs'.  So it's not clear to me if I can just use this for the bridge simulation without hooking up the temperature terminals or worrying about the Sensor Emulator jumper settings?

So if there is any documentation updated for using the Sensor Emulator with the latest PGA309 Test Board and USB DAQ Platform set please advise.

I also plan on using the PGA309 Test Board and USB DAQ Platform set with the (2) PGA reference designs PCBA;s I have constructed as well.

  • 0
    TI__Mastermind 27715 points

    Hello Michael,

    It is straightforward to connect the Sensor Emulator EVM to the input of the PGA309EVM-USB. Follow these steps:

    • Power the Sensor Emulator with a ±12V supply as described on p.18 of its reference guide. Ensure that the GND of the Sensor Emulator is common to the GND of the PGA309 Test Board.
    • On the PGA309 Test Board, set jumpers JMP4, JMP5, JMP6, and JMP17 to position "Ext" for external input. Set JMP12 to position "Vexc" to select Vexc as the excitation voltage source.
    • Connect Vin1 and Vin2 at terminal block T4 of the PGA309 Test Board to Vin+ and Vin- at terminal block T2 of the Sensor Emulator.
    • Connect Vsensor at terminal block T1 of the PGA309 Test Board to Vexc at terminal block T2 of the Sensor Emulator.

    You are now ready to use the Sensor Emulator EVM as the input to the PGA309 Test Board. Monitor and configure the Sensor Emulator EVM as described in its reference guide.

    Best regards,

    Ian Williams
    Linear Applications Engineer
    Precision Analog - Op Amps

  • 0 in reply to Ian Williams
    Intellectual 425 points

    Thanks, that part is clear now.  

    I have a few more questions:

    1. In the PGA309 Calculator application there are fields with radio buttons for the "Normalized Sensor Data" and another "Measured Sensor Data".

    I'm not clear on the usage, of those fields, if I input data into the  "Measured Sensor Data" and have it's radio button selected then it's values are also effecting the "Normalized Sensor Data" fields.

    If I am to understand this shouldn't I be using one or the other? Either "Normalized Sensor Data"  or "Measured Sensor Data"?

    My entered data into the "Measured Sensor Data" fields shouldn't that be the actual voltages I read with a VM on the Vin+ and Vin- of the actual real sensor?

    And "normalized" just means some theoretical values of the sensor based on a datasheet of the sensor?  

    I guess I am getting confused on this as the data entry in one is effecting the data entry of the other.  In others words I select and set values in "Measured" but the un-selected "Normalized" is being effected. Is this just a quirk in the software?

    2. The Sensor Emulator EVM itself.

    Am I just setting voltage levels here representing various levels of "strain" voltages that would be represented in the zero to span range?  Considering the fact that I don't really need to vary or simulate temperature, but I'm not understanding if I am able to really choose and simulate my bridge ohms there as well. 

    Please advise.  Thx I'm getting closer.

  • 0 in reply to Michael Parrish
    TI__Mastermind 18037 points

    Michael,

    1. Two part answer to your question 1:
      1. The "Normalized Sensor Data" means that the data has been divided by the sensor excitation voltage so that the sensor span and offset are in mV/V. For example, a sensor that has an offset of 5mV and an excitation of 5V has a normalized offset of 1mV/V.
      2. The “measured sensor data” on the other hand is the actual value measured at the output of the sensor. Note that this is given as offset and full scale. So, a sensor that has an offset of 1mV and a full scale of 6mV will have a span of 5mV. Remember Span = FullScale – Offset.

    For example, translate normalized to measured:

    Vexe= 5V

    Normalized Offset =1mV/V

    Normalized Span = 4mV/V

     

    Measured offset = (1mV/V)(5V) = 5mV

    Measured span = (4mV/V)(5V) = 20mV (not shown on calculator)

    Measured full scale = measured offset + measured span = 5mV + 20mV = 25mV

     

     2.         The purpose of the simulator is to see how the different gain blocks work to amplify and shift the milli-volt inputs to volt outputs. The simulator can also show if any internal voltage ranges are violated. In other words the common mode and output swing limitations of the amplifiers is verified in simulation.

     

    Note: the calculator tool was developed to work with a very old generation of the evaluation module (EVM). This old software was fairly primitive and required a lot of manual calculations and adjustments. The current EVM software does the calculations automatically as part of the calibration. So, for example, you don’t need to manually set any of the gain or offset blocks in the EVM software. All the gain and offset blocks are automatically adjusted. Nevertheless, we decided to leave the old calculator software on the web in case someone wanted to see the gain and offset calculations. My point is that you should definitely look at the modern EVM hardware and software if you haven’t already. I wouldn’t suggest focusing too closely on the calculator software.

     

  • 0 in reply to Art Kay
    Intellectual 425 points

    Thanks all is clear now.  Yes, I understood about the new software automatically figuring out all the gory details of gain and offset for me and have been able to use it.

    The old calculator is still useful to me in that I can predict what offset and span values the sensors need to be. My current sensor is just outside the boundaries so this tool is helpful in showing why and where I am out.