enabling LSE and no crystal present

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STM32_Newbbe
Posts: 47
Joined: Thu Nov 05, 2020 10:26 am

enabling LSE and no crystal present

Post by STM32_Newbbe »

Hi,

I created a custom board design (for L412KB) and erratically selected the Nucleo-L412 as a board instead of generic L412 and wondered why the board did not come up on reset. Flashing firmware works fine, either by ST-Link or USB-DFU so _something_ must be right...

But no output on IOs or Serial or anything ...

I could narrow it down to the different clock settings, namely activating the LSE clock.
Nucleo has a 32k crystal, but my design doesn't !

Is it really that simple, that the missing crystal causes the controller to sit locked in a startup routine waiting for the clock? :lol:
Even though the LSE is (to my knowing) not crucial to the functioning of the controller? :roll:
phdegen
Posts: 1
Joined: Tue Sep 12, 2023 4:37 pm

Re: enabling LSE and no crystal present

Post by phdegen »

Hi,

I'm having a similar issue. I made a custom STM32WB55CGUX board and the serial fails to work over usb cdc. (using the STM32duino generic board configuration) I dont have a LSE xtal either. I set up a USB CDC application from the STM32cubeMX tool (choosing HSI based USB clk) and it works nicely. I supposed that the clock configuration is just killing it so I included the one used in the cubeMX example but this did not help.

Did you solve your issue in any way? Any other idea to make it work?

Thanks.
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fpiSTM
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Re: enabling LSE and no crystal present

Post by fpiSTM »

Simply enable core logs and you should see where it's failed.
It is hard to manage all possible cases.
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