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Associate III
June 27, 2025
Solved

STM32F303 Crystal and Boot pin

  • June 27, 2025
  • 2 replies
  • 281 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 ?

 

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

KnarfB
KnarfBBest answer
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
Associate III
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,