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June 27, 2025
Solved

STM32F303 Crystal and Boot pin

  • June 27, 2025
  • 2 replies
  • 280 views

Hello Friends,

Most STM32 based Evolution / Development Board has Crystal 32.768 Khz and Boot switch connected.

 

In my Custom design board , I do not need RTC Function and Bootloader to load.

8 Mhz Crystal is used for Master Clock.

 

Can I remove 32.768 khz Crystal and Bootloader Switch from Boot0 pin ?

What should be default level maintain on these pins after removing both ?

 

    This topic has been closed for replies.
    Best answer by KnarfB

    The crystal can be omitted, the pins can be left open or used as GPIO pins. BOOT0 should be connected to GND via a 10k current limiting resistor. See AN4206 Application note "Getting started with STM32F3 series hardware development"

    hth

    KnarfB

    2 replies

    KnarfBAnswer
    Super User
    June 27, 2025

    The crystal can be omitted, the pins can be left open or used as GPIO pins. BOOT0 should be connected to GND via a 10k current limiting resistor. See AN4206 Application note "Getting started with STM32F3 series hardware development"

    hth

    KnarfB

    bsutharAuthor
    Explorer
    July 25, 2025

    Thank you , KnarfB

    That is Helpful.

    About Reset Pin in AN4206 ( Page 31) , NRST pin is not Connected to 3.3V , it is left Floating with Capacitor.

    Is that Okay ? 

    Regards,