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Graduate II
October 6, 2025
Question

STEVAL-STWINBX1 examples doesn't respect STM32U585 datasheet

  • October 6, 2025
  • 1 reply
  • 443 views

The datasheet of STM32U585 say that "For operation with voltage higher than Min (VDD, VDDA, VDDUSB, VDDIO2) +0.3 V, the internal pull-up and pull-down resistors must be disabled." (chap. 5.3.1).
The STEVAL-STWINBX1 use a VDDA of 2.75V and a VDD of 3.3V => Min (VDD, VDDA, VDDUSB, VDDIO2) +0.3 V = 3.05V < VDD = 3.3V.
But in the examples provided for STEVAL-STWINBX1, pull up and down are used with a VDD of 3.3V.
So which is correct, the datasheet or the examples ?

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    1 reply

    Technical Moderator
    October 9, 2025

    Hi @nicolas ,

    Reviewing the product datasheet, I think that you are referring to the following note:

    AmelNASRI_0-1760026503246.png

    This note is applicable for VIN (the voltage input that may be applied for device pins) and not to VDD:

    AmelNASRI_1-1760026546342.png

    Therefore, I believe that the STEVAL-STWINBX1 design aligns well with the operating conditions described in the datasheet and in AN5373Getting started with STM32U5 MCU hardware development.

    Additionally, I received confirmation that the STEVAL-STWINBX1 has been used for a considerable time with various firmware and demos without any reported issues.

    -Amel

    nicolasAuthor
    Graduate II
    October 10, 2025

    I'm using SDDataLogFileX with STEVAL-STWINBX1. In the code i saw that pull up are used for I2C2 (I2C2_MspInit). When measuring on the I2C2 pins, i saw a signal that go up to ~3.2V. So for my understanding it doesn't respect the datasheet because it's higher than 2.75V + 0.3V.

    Technical Moderator
    October 10, 2025

    I assume that there is no external voltage input for the I2C pin, so it is normal that the voltage is aligned with VDD.