Do I need an external crystal if I want to use the STM32F412 USB FS device ? or can I use the internal HSI ?
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‎2020-07-08 11:30 PM
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‎2020-07-08 11:41 PM
Yes, the internal oscillator can not provide the accuracy required by USB.
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‎2020-07-09 1:19 AM
STM32 chips with crystal-less USB are
STM32F072
STM32F078
STM32F04x
STM32F105/107
STM32H743/753
STM32H750
STM32L0x2
STM32L0x3
STM32L4x2
STM32L4x3
STM32L4x5
STM32L4x6
STM32L4Rx
STM32L4Sx
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‎2020-07-09 6:42 AM
I wonder how would 'F105/107 work crystal-less. Can you please post source?
JW
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‎2020-07-09 9:50 AM
@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.
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‎2020-07-09 10:56 AM
@Imen DAHMEN​ Hi, this appears to be an error, can you please have a look at it?
Thanks,
Jan
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‎2020-07-09 1:42 PM
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.
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‎2020-07-09 2:40 PM
The G4 series also has crystal-less USB using the CRS.
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‎2020-07-10 8:34 AM
Ok, I will check and raise it internally for fix.
Thanks
Imen
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‎2020-07-10 2:30 PM
Thanks, Imen.
JW
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