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STM32F4 Use HSI for USB Clock

JBret.1
Associate II

I want to use STM32F413 for my PCB design. I need USB data lines for communicating with a computer. Ideally, I would not have any oscillator on the PCB to save space. I noticed that's it's not possible to use HSI for the USB clock on CubeMX. Can I use pin PA8 as MCO to output HSI and route it to PH0 ? This way HSI and HSE are connected though the PCB. On CubeMX it seems possible, however, I don't know if it can work in reality. Are there some consideration hat I need to take to ensure this will work? Here are some screenshots of the CubeMX configuration and PCB schematic. Thanks

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12 REPLIES 12

Hi, how can you setup Start of Frame signal? the STM32 will only operate in device mode so if it's possible to use SOF instead of a crystal it would be an ideal solution. From my understanding, the host sends a signal every 1 ms (LS) or 125 us (HS). How does that the SOF signal transmits to the STM32 device? The STM32 will be connected to the computer with Micro USB connector (VBUS, D+, D-, GND). Do I need to activate a function in CubeMX to sync the data with SOF? Thanks0693W0000059CpiQAE.png

Huge thanks. I decided to put and oscillator to ensure stability as this product will be sold to customers. If use a clock oscillator I only need to connect PH0 to the OSC pin on the chip? (I leave PH1 floating?)

Oscillator I choose: https://www.digikey.ca/en/products/detail/abracon-llc/ASFLMB-8.000MHZ-LY-T/2624517

0693W0000059CwoQAE.png0693W0000059CwtQAE.png

> There are some chips that can use HSI along with the clock recovery system (CRS) to manage crystal-less USB, but the STM32F4 is not one of them.

As TDK already told you - there is no such thing in F4 series. Ir you want CRS, then take a look on L4 and G4 series.