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ADS8320: How to interface ADS 8320 with ESP32_devkitc_v4 board and example code to read data from ADS 8320.

6448045
Prodigy 110 points
Part Number: ADS8320
Other Parts Discussed in Thread: ADS8860, ADS8860EVM-PDK

Dear Sir / Madam,

I am using ESP32_devkitc_v4 board for my electric motor predictive maintenance project. I am using accelerometer (ADXL1002Z) to measure vibration data from the motor at 10kHz sampling rate. However, because the ADC resolution in ESP32 devkit board is low resolution (10 bits), I can't do analog to digital conversion correctly with onboard ADC. Therefore, I am using 16 bit ADC from TI (ADS8320), but I am not very sure about how to interface ADS 8320 with ESP32_devkitc_v4 board. 

Therefore, could you guide me on how to interface ADS 8320 with ESP32_devkitc_v4 board? and I would like to know the Arduino example code on how to read data from ADS 8320?

Thanks,

Susan.

  • 0
    TI__Mastermind 36240 points

    Hello Susan,

    Welcome to the TI E2E community.  

    The ADS8320 uses a standard 3-wire SPI interface.  We do not have any example code that I am aware of to use with an Arduino kit, but you should be able to get this working with your processor.

    The /CS line is typically connected to a GPIO, and bit banged in software.  The processor should have a SPI peripheral that you can use to generate the DCLOCK (SCLK) and capture the Dout from the ADS8320.  You can set the system up to transfer 3 8b blocks (bytes) for a total of 24 bits.  In this case, B15 (MSB) of the conversion result will be D17 of the 24b data capture, and B0 (LSB) will be D2 of the 24b capture.  You can then bit shift the result and mask the upper 8b to get your final 16b result.  For details on the interface, please refer to section 7.4.2 in the datasheet, as well as Figure 29.

    Also, an alternative to the ADS8320 that will be a little easier to work with is the ADS8860.  This part uses the same 3-wire SPI interface, but you only need to clock a total of 16b for your conversion result.  If you decide to use this device, refer to Figure 1 in the ADS8860 datasheet for details on how to read data.

    For more information on how the SPI bus works, please take a look at TI Precision Labs - ADC's, Topic1 - Digital Communications Basics

    https://training.ti.com/ti-precision-labs-adcs-spi-serial?context=1139747-1140267-1128375-1146616-1146615

    Regards,
    Keith Nicholas
    Precision ADC Communications.

  • 0 in reply to Keith Nicholas
    Prodigy 110 points

    HI Nicholas,

    Thank you for your reply

    I would like to clarify what do D17 and D2, refer to? Does D17 means DCLK cycle 17?

    In addition, the accelerometer output is go through the Sallen Key Low Pass Filter of cut off frequency = 3.5kHz. Output of the filter is single ended, but the ADS8320 required differential input.

    So, could you recommend differential amplifier to convert from single ended to differential pair ?

    Thanks, 

    Susan 

  • 0 in reply to 6448045
    TI__Mastermind 36240 points

    Hi Susan,

    Yes, D17 means DCLK cycle 17.  Hopefully the below drawing will help.

    The ADS8320 does have a differential input, but the negative input should be tied to ground.  In this case, you do not need a differential input amplifier.

    Please refer to the TI Precision Labs SAR ADC EVM user's guide for a good example on how to drive the ADC inputs (The same circuit will work with the ADS8320 as well).

    https://www.ti.com/lit/ug/sbau307a/sbau307a.pdf

    Regards,
    Keith

    Regards,
    Keith

  • 0 in reply to Keith Nicholas
    Prodigy 110 points

    Dear Keith Nicholas,

    The TI Precision Labs - ADC's, Topic1 - Digital Communications Basics video cannot be accessed. Could you help me check ?

    Thanks,

    Susan

  • 0 in reply to 6448045
    TI__Mastermind 36240 points

    Hello Susan,

    These are new topics that we found some issues with and decided to pull them off of the web to update.

    I do not have a specific time frame, but they will be posted back on ti.com as soon as possible.  Please keep checking the TI Precision Labs - ADC site for the updated version.

    Thanks,

    Keith

  • 0 in reply to Keith Nicholas
    Prodigy 110 points

    Dear Sir,

    I am planning to use ADS8860 instead of ADS8320. 

    May I know can SSOP 16 chip package adapter fit with ADS8860 which is VSSOP10 package?

    The chip package adapter is from this website

    Thank  you.

    Susan

  • 0 in reply to 6448045
    Prodigy 110 points

    Hello Sir,

    How about this TSSOP 10 adapter?

    Can I use this TSSOP adapter for ADS8860?

    Thank you.

    Susan

  • 0 in reply to 6448045
    Prodigy 110 points

    Hello Sir,

    If there is no available chip package adapter for ADS8860, can you suggest me is there any other possible way of testing ADC using ADS8860 with esp32 microcontroller? Because I found that vssop chip adapter package is not available widely in Singpaore shop electronic component shop.

    Thank you

    Susan.

  • 0 in reply to 6448045
    TI__Mastermind 36240 points

    Hello Susan,

    I was not able to view the sockets that you refer to.  However, I do not think any of these will work with the VSSOP10 package that the ADS8860 uses.  Please take a look at page 45 of the ADS8860 datasheet for details on the package measurements.

    The quickest way to evaluate the ADS8860 is to purchase the evaluation kit, ADS8860EVM-PDK.  This kit comes with two boards; a data capture board with USB interface, and a separate board with the ADS8860, input amplifier, voltage reference and local supplies.  You can directly connect your own ESP32 development board to the ADS8860EVM board using jumper wires.  The ADS8860EVM user's guide includes full schematics to help with custom configurations.

    Regards,
    Keith