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External crystal on STM32F303CCT6

MSzła.1
Associate III

Hello all, I don't know why but my MCU STM32F303CCT6 don't work with external crystal, below schematics:


_legacyfs_online_stmicro_images_0693W00000bkpe2QAA.pngThe used crystal is ABM3B-8.000MHZ-10-1-U-T with load capacitors 10pF. Later I find in STM Datasheet that I should use resistor on OSC32_OUT pin. Is the resistor necessary to work? Or maybe i use wrong crystal? Thanks a lot for help to solve my problem :)

1 ACCEPTED SOLUTION

Accepted Solutions
AScha.3
Chief III

no - you just connected to the wrong pins !

crystal for cpu clock is on PD0+1 , but you connected to 32kHz clk /crystal at PC14+15 !!!!

so connect it to right pins or use internal clk...

If you feel a post has answered your question, please click "Accept as Solution".

View solution in original post

6 REPLIES 6
ONadr.1
Senior III

This should help

AN2867

Oscillator design guide for STM8AF/AL/S, STM32 MCUs and MPUs

MSzła.1
Associate III

I saw this document but unfortunately after ordering the PCB. But it is puzzling to me that, for example, bluepill board designs have different solutions, one with a 1M resistor and the other without resistors. In the second case, this Bluepill board works, but unfortunately not in my case.

WeAct bluepill crystal schematics:


_legacyfs_online_stmicro_images_0693W00000bkrYaQAI.png 

and noname bluepill board:


_legacyfs_online_stmicro_images_0693W00000bkrYkQAI.png 

My PCB crystal schematics is exactly as in Weact bluepill?

Could I have damaged the crystal too high temp, hot air soldering?

AScha.3
Chief III

no - you just connected to the wrong pins !

crystal for cpu clock is on PD0+1 , but you connected to 32kHz clk /crystal at PC14+15 !!!!

so connect it to right pins or use internal clk...

If you feel a post has answered your question, please click "Accept as Solution".

> bluepill board designs

They contain a STM32F103 (and these days, a random choice of some of the dozen clones), that's a different mcu with different oscillator design, and potentially uses a different crystal than you. So, you are comparing apples to a selection of various fruits and often also vegetables.

Read AN2867, mainly chapter 7, and also the parts which deal with the load capacitors calculation.

JW

Thanks a lot! You have right

Nice catch! :)

JW