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Explorer II
April 30, 2024
Question

I2C channels as pull-up in STM32F103C8T6

  • April 30, 2024
  • 3 replies
  • 1395 views

Hello everyone,

I want to configurate the I2C channels as pull-up in STM32CubeIDE for STM32F103C8T6, but I couldn't set it. 

It looks like in the attached image. It just shows n/a in configuration.

How I set it as pull-up? 

Please inform me. Thanks.

 

hdhdhd_0-1714481859079.png

 

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    3 replies

    Super User
    April 30, 2024

    The internal pull-ups are not suitable for use as I2C bus pull-ups - you need to use external pullups.

     

    EDIT:

    See this post for the effect of too-high and too-low pullups:

    https://electronics.stackexchange.com/a/473799

     

    Technical Moderator
    April 30, 2024

    Hi @hdhdhd 

    Internal pull-ups are not recommended for I2C. Pull-ups must be adapted to the I2C bus speed and to the bus load.

    Super User
    April 30, 2024

    Hi,

    i just tried , yes, on F103 no pullups to set , only n/a .

     

    But on F401 i tried also, here pullups possible :

    AScha3_0-1714494422254.png

    So for pullups - take another cpu . :)

     

    Super User
    April 30, 2024

    @AScha.3 wrote:

    So for pullups - take another cpu . :)


    Or just use the proper external pullups - the internal ones (when available) are likely to be too large.