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CN0540 Questions

Category: Datasheet/Specs
Product Number: CN0540. 24-Bit Data Acquisition System for IEPE Sensors

Dear all,

I need to design a 4 IEPE channels DAQ board so I´m very interested in Analog Devices CN0540 development board. But before adquiring de CN0540 I would like to solve several doubts.

About CN0540:

  • I Don´t understand how to manage/control DAC to ADC control loop. I saw DAC have an I2C interface so I supose that the user has to connect this interface to its control DAQ board (E.g. DE10-Nano FPGA Board), then the I2C wil be controled by software through I2C interface. Is correct? If afirmative answer. Does the software include into DE10-Nano FPGA Board provide the algorithm to apply in DAC through I2C interface?

Otherwise , How the DAC control would be?

About EVAL-AD7768-4FMCZ-UG-921

  • This evaluation board allow to take measures in 4 channels simultaneously, but is it suitable for use directly to connect IEPE sensors? I think it is not posible. I think is necesary to add several devices perchannel to make it work (ADG5421 F, LT2606 DAC, LT3092…etc). Could you give any extra information intis way?

Thanks,

Parents
  • FormerMember
    +1 FormerMember

Hi,

So the DAC is controlled using the I2C bus as you mentioned, you must have this in order to communicate with the DAC.  The Current CN0540 software on the DE10-Nano already has that communication path working.  The current implementation does the ADC/DAC control loop at the beginning of the program and then uses those values for the duration of the conversations.  You can initiate the control loop at any time though. 

As for the EVAL-AD7768-4FMCZ, I would not recommend using that directly with 4 IEPE sensors.  The amount of additional signal conditioning required would be a large undertaking.  You would be better off with 2 or more setups of the CN0540 to test out your sensors and system with.  

Cheers,

Brandon

  • Hi Brandon, I need to do some more questions to evaluate the CN0540 purchase:

    1) I don´t really understand the ADC/DAC control Loop. I suposed that the loop is used to control the IEPE sensor input so it would be changing values continously through the I2C interface as well as the IEPE sensor input is changing, but in the last message you said to me “start control loop at the beginning of the program and then uses those values for the duration of the conversations”. Please, Could you explain to me better the working of ADC/DAC loop and its real function? I would e gratefull because I think I am wrong.

    2) Could you tell me wich was the minimun pack that I need to purchase to test de CN0540 eval Board? I refer if its necessary to buy an IEPE sensor, a CN0540 Eval board and a Cora Z7 or DE10 nano Board or for example I could use mi Own MCU board to check CN0540 eval Board (For example an STM32 eval board that I already have).

    3) I have seen that Cora Z7 or DE10 nano Board use a powerful ARM CORTEX A9 microcontroller. Is it necessary o is posible to use a less powerful MCU? I need to know to keep it in mi mind to my future Board design.

    4) Is the IEPE input could be simulate using a signal generator instead of IEPE sensor o is necessary to connect physically an IEPE sensor? I only ask it to evaluate the possililities.

    Thank you very much for your attention.

  • Reply
    • Hi Brandon, I need to do some more questions to evaluate the CN0540 purchase:

      1) I don´t really understand the ADC/DAC control Loop. I suposed that the loop is used to control the IEPE sensor input so it would be changing values continously through the I2C interface as well as the IEPE sensor input is changing, but in the last message you said to me “start control loop at the beginning of the program and then uses those values for the duration of the conversations”. Please, Could you explain to me better the working of ADC/DAC loop and its real function? I would e gratefull because I think I am wrong.

      2) Could you tell me wich was the minimun pack that I need to purchase to test de CN0540 eval Board? I refer if its necessary to buy an IEPE sensor, a CN0540 Eval board and a Cora Z7 or DE10 nano Board or for example I could use mi Own MCU board to check CN0540 eval Board (For example an STM32 eval board that I already have).

      3) I have seen that Cora Z7 or DE10 nano Board use a powerful ARM CORTEX A9 microcontroller. Is it necessary o is posible to use a less powerful MCU? I need to know to keep it in mi mind to my future Board design.

      4) Is the IEPE input could be simulate using a signal generator instead of IEPE sensor o is necessary to connect physically an IEPE sensor? I only ask it to evaluate the possililities.

      Thank you very much for your attention.

    Children
    • FormerMember
      0 FormerMember
    in reply to TSTEngineer

    Let me try to answer as much of this as possible.

    1) I believe the ADC/DAC control loop is primarily for offsetting the DC bias level coming from the IEPE sensor.  You can think of that sensor as having two components, the AC waveform which is the data you want to collect and analyze and the DC component which is generated from the excitation which needs to be within the rage of the input stage of the signal conditioning front end/digitizing circuitry.  The control loop there is really providing an offset compensation to the system when your sensor is in an "off" state, and this can be done multiple times in software for instance if you are changing sensors or perhaps you are looking to recalibrate because your sensor was moving during the initial compensation.

    2) You need an IEPE sensor, the EVAL-CN0540-ARDZ, either the DE10-Nano or Coraz7-07s, and the ADI Kuiper Linux software (which is downloadable from the user guide)  I would advise against using your own MCU board because our software will not work with that out of the box. 

    3) In general you are correct, the A9 is certainly a bit overkill for a product implementation but the goal with this platform is to provide an unimpeded data stream from the sensor to higher level mathematics tools such as MATLAB or Tensorflow.  This is a development platform to help determine the condition monitoring algorithms you are designing.  Once completed, the concept would be to take the same EVAL-CN0540-ARDZ, place it on something like your STM micro and embed the firmware and algorithm to look for the events/conditions you have coded into your algorithm.

    4) I don't have a direct piece of test equipment that I could give you off hand, but any signal generator that can super impose an AC signal (1kHz-40kHz) onto a DC offset (7V-13V I believe) should be good enough for a sanity check/evaluation.   If you do this remember to remove the current excitation coming from the CN0540 in hardware or turn it off using the software. 

    Cheers,

    Brandon

  • Thank you very much Brandon, a great and clear explanation.

    One more question please, as you said "The control loop there is really providing an offset compensation to the system when your sensor is in an "off" state, and this can be done multiple times in software for instance if you are changing sensors or perhaps you are looking to recalibrate because your sensor was moving during the initial compensation."

    but I was thinking about it and I suppose there will be a way to do it automatically, insn´t it?

    I mean that you will be able to change the kind of sensor that you are connected to CN0540 and the system will detect automatically de change (using any signal or the voltage change, I don´t know how) and make the compensation through de control loop by software starting I2C comunnication with DAC ¿Is correct?

    thanks