Do I need an external crystal if I want to use the STM32F412 USB FS device ? or can I use the internal HSI ?

[berendi]

Yes, the internal oscillator can not provide the accuracy required by USB.

[frank.zhao]

STM32 chips with crystal-less USB are

STM32F072

STM32F078

STM32F04x

STM32F105/107

STM32H743/753

STM32H750

STM32L0x2

STM32L0x3

STM32L4x2

STM32L4x3

STM32L4x5

STM32L4x6

STM32L4Rx

STM32L4Sx

[waclawek.jan]

I wonder how would 'F105/107 work crystal-less. Can you please post source?

JW

[frank.zhao]

@Community member​ I'm reading AN4879 "USB implementation on STM32 products", section 2.1, table 4 "USB implementation on STM32 mainstream products". F105/107 does indeed have a X under crystal-less. But reading the datasheet I can't see that feature.

[waclawek.jan]

@Imen DAHMEN​  Hi, this appears to be an error, can you please have a look at it?

Thanks,

Jan

[S.Ma]

To complement: Most STM32L4 have MSI which generates 48MHz from the 32.768kHz LSE and is suitable for USB Device function without LSE.

In Host mode, HSE crystal becomes required.

[Terry Greeniaus]

The G4 series also has crystal-less USB using the CRS.

[Imen.D]

Ok, I will check and raise it internally for fix.

[waclawek.jan]

Thanks, Imen.

JW