Pull-up before/after voltage divider for i2c

Discussion in 'Digital Circuit Design' started by Synaps3, Aug 2, 2016.

  1. Synaps3

    Thread Starter Member

    Jun 5, 2013
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    I am building my first circuit for i2c and the chip I am controlling using an MCU requires a pull-up resistor on SDA and SCL. I am using a voltage divider because my MCU is 5V and I need 3.3V. Does it matter what side of the divider I put the pull-up on? Based on the layout the 3.3V side would be much easier?
     
    Last edited: Aug 2, 2016
  2. MrChips

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  3. ericgibbs

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    Last edited: Aug 3, 2016
  4. GopherT

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    Nov 23, 2012
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    Do you need bidirectional or is one-way good enough?
     
  5. AlbertHall

    Well-Known Member

    Jun 4, 2014
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    Don't you need bidirectional for the acknowledge from the slave?
     
  6. GopherT

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    Nov 23, 2012
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    Sorry, i2c. I had SPI on my brain from another discussion.
     
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