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BMP085 - ADC converter type ?

Discussion in 'Microcontrollers, Programming and IoT' started by syncout, Nov 27, 2017.

  1. syncout

    syncout

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    Nov 27, 2017
    Hi,

    I have read BMP085's datasheet and it says BMP085 has a 16-bit adc converter, and it takes 8MSB and convert it, and then it takes 8LSB and convert it too. I'm not 100% sure if it is correct, but if I am wrong, so is it a SAR adc? Because I don't know another adc that uses MSB and LSB to covert signals.

    And, if it is as I said, why does it take first 8MSB and then 8LSB?

    Thanks!

    datasheet: https://www.sparkfun.com/datasheets/Components/General/BST-BMP085-DS000-05.pdf
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Where did you read this? I can not find any reference to this in the datasheet.
     
    syncout likes this.
  3. syncout

    syncout

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    Nov 27, 2017
    Thanks for you quickly reply!

    Well, I am not pretty sure about what I'm talking, but I found "this information"(probably wrong) on page 18.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    What's stated there is that you read the 16 bit A/D conversion value by reading 2*8 bits.
    This is no reference to the actual mode of conversion.
     
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  5. syncout

    syncout

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    Nov 27, 2017
    Do you guess why does it happen? If it is a 16-bit A/D converter, why does it takes 2*8bits? It is confusing to me.

    Thanks for your reply!!
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
  7. BobK

    BobK

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    Jan 5, 2010
    And because they would need 8 more pins to output all 16 bits at once.

    Bob
     
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  8. syncout

    syncout

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    Nov 27, 2017
    Thanks you!! I got it! In your link, it explains how the data is transmitted, thanks!

    Thanks for you reply Bob! But I didn't get these "more 8 pins", are you talking about I2C protocol? If so, I got it! Thanks!!
     
  9. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    That would be true for a parallel interface, not a serial one as I²C ;)
     
  10. BobK

    BobK

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    Jan 5, 2010
    Duh, I shouldn’t have posted without looking at the datasheet. :oops:
     
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