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mwp
mwp
Associate III
August 14, 2019
Question

Can any STM32's operate USB without HSE?

  • August 14, 2019
  • 2 replies
  • 722 views

Hi all,

I know the older generations of STM32s cant use USB without the use of an external osc.

Has this changed at all with the newer L4, F4, G4, etc micros?

Have the HSI's improved enough?

Thanks in advance.

This topic has been closed for replies.

2 replies

KnarfB
KnarfB
Super User
August 14, 2019

Well, the STM32F042x4 / STM32F042x6 data sheet states "USB 2.0 full-speed interface, able to run from internal 48 MHz oscillator and with BCD and LPM support"

and it worked for me (on a prototype).

Frank

waclawek.jan
waclawek.jan
Super User
August 14, 2019

It's thanks to a so called Clock Recovery System, CRS, a module which fine tunes the internal RC oscillator to USB's SOF (or to an external pin).

AFAIK it's in L4 (but not in 'L476), 'L0, 'F0, 'H7; I don't know how's it with 'G4.

JW

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