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PGA900: Sampling Rate

Keith Keller
Expert 7230 points
Part Number: PGA900

Hello,

We would like to ask about the internal polling rate of the PADC in the PGA900.

Looking through the datasheet and it seems to only mention the output I2C rate, but not how fast the PGA900 itself samples the analog signal at.

Could you please let us know?  Thank you, Keith

  • 0
    TI__Guru** 113765 points

    Hi Keith,

    This is mentioned a number of times throughout the datasheet for both the pressure and temperature ADC as 64us or 128us.  Below is one example:

    You will notice that below the Output sample period is the selection on interrupt control as to either every sample or every 4 samples.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    TI__Expert 7230 points

    Hello,

    We’d like to ask for clarification.

    • Does the output sample period match that of the internal sampling rate that the M0 can see?
    • Or can we only poll at these two rates even from the onboard M0 chip?

    Thank you, Keith

  • 0 in reply to Keith Keller
    TI__Guru** 113765 points

    Hi Keith,

    I'm not entirely sure how to answer this as the M0 doesn't see anything until a program is loaded.  In other words it is in a reset state.  The ADCs run independently to the M0.  How often the M0 'sees' the conversion data depends on the firmware code.  Generally you would create an interrupt function for handling the new conversion data as it comes in.  The control setting for triggering an interrupt is either after every conversion or after every 4 conversions.

    As for polling, I guess you could do that, but that seems to be a waste of processor time or for having a consistent loop when interrupts can handle this for you.

    Best regards,

    Bob B