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PCM1865EVM: PCM1865EVM / PCM1862: Can it be used for sensing a wheatstone bridge ?

Stefan Baessler
Prodigy 30 points
Part Number: PCM1865EVM

Hi Experts,

is it possible to use the PCM186x for sensing wheatstone bridges ?

The part offers good ADC, fast sampling and valuable filtering options, that would make it attractive to use.

Well a wheatstone bridge type of pressure sensor is not a real microphone...

However, it´s also not too far of it. It has a bias of half of power supply (VDD=3.3V). The signal is differential.

Signals of interest are in range 1Hz till 10kHz. So I wonder if it works with PCM186x ?!

Any advise how to connect and setup in PurePath?  (Currently try to use "differential input" on Ch1 right with 2P - 2M, Gain0)

Is there a code part  (C-code) available for reading out the ADC values by I2C ?

and/or

How can the PurePath console help in case by using the direct I2C Read/Write function ?

Thanks,

Stefan 

  • 0
    TI__Expert 5645 points
    Hi Stefan,

    Welcome to e2e Forum.

    I'm not very familiar with the wheatstone bridge type of pressure sensor but the requirements you have given may be perhaps met w PCM186x. As you eluded, this is a very good performance ADC w flexible feature set including the filtering options. we also have other precision ADCs for this type of applications which I can discuss w concerned team mates and try to shortlist for you.

    As you know, the audio ADCs are not thoroughly tested below a certain input freq and in most audio applications, we typically have internal/external HPF in the front-end. I'll look into this and will get back to you w more detailed proposals.

    Regarding the C code, we do not have any examples for reading out ADC values by I2C but PPC2 can provide the detailed register configuration values for a given configuration.

    Finally, PPC2 has a tab called 'DIRECT I2C READ/WRITE' which will allow you to do direct read/write to PCM186x. If you do not have PPC2, please request for the SW and we will make sure you have access to download the same.

    Thanks and Best regards,
    Ravi
  • 0 in reply to Ravi Patil
    Prodigy 30 points

    Hi Ravi,

    thank you for your answer. 

    PPC2 I have available and working now.

    Can you indicate which addresses contain the 24bit ADC values ?

    I´d give it a try for low frequency range singals then. The needed range is starting at about 5-10Hz till 30kHz.

    Is 5Hz already too low ?  What happens in case ?

    BR,
    Stefan