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Original question:

PGA302: Unable to unlock EEPROM after locking

PGA302: Disable temperature compensation

Chris Hadsock
Prodigy 50 points
Part Number: PGA302

Is it possible to disable temperature compensation on the PGA302 using the PGA302 GUI?

  • 0
    TI__Guru** 113765 points

    Hi Chris,

    The compensation engine is a part of the firmware code running on the M0 core microcontroller of the PGA302.  If the microcontroller is not 'running' but instead in the reset state, the compensation does not take place.  From the GUI at the top there is a selection for setting the Microcontroller State.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 50 points

    Hi Bob,

    Can the compensation be permanently disabled in the running state?

    Thanks,
    Chris

  • 0 in reply to Chris Hadsock
    TI__Guru** 113765 points

    Hi Chris,

    There are 2 key coefficients, H0 (offset) and G0 (gain).  Check out the compensation formula 4 on page 37 of the datasheet.  If only these 2 coefficients are used you get the equation of a line y = mx + b where H0 relates to b and G0 relates to m.  G0 and M0 are normalized to 2^14 bits and stored in EEPROM.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 50 points

    Hi Bob,

    Sorry I'm a little confused. Can those EEPROM values be overwritten within the GUI to prevent the temperature compensation from coming into play? The pressure transducer sensor we've integrated already handles temperature compensation and we suspect the PGA302 is causing it to overcompensate at higher temperatures. 

    Thanks,
    Chris

  • 0 in reply to Chris Hadsock
    TI__Guru** 113765 points

    Hi Chris,

    Yes, if you look at the compensation equation you will notice that if the coefficients are zero in the eeprom then the data will be zero.  So you wouldn't want all of them zero.  But H0 can be zero (no offset) and G0 can be set to a gain of 1 ( (1 * 2^14)-1 in binary 2's complement as the EEPROM data is the normalized to 14 bits 0x3FFF).  All other coefficients should be 0 which would then eliminate the temperature compensation.

    Best regards,

    Bob B