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CaptainJL
Associate
July 1, 2023
Solved

Stm32 usb and hsi - not sure what is wrong.

Hey all,
I am wondering if anyone has some insight into why i cannot get a usb connection working (trying as HID).
I can power up and debug the MCU (STM32F103RBT6), but cannot get the USB to connect.

For the HSI I am using 10pF for C1 and C2, and a 1000 ohm resistor for Rext (Rosc). My oscillator is the 7M16000024 (16Mhz, 10pF load capacitance according to https://www.digikey.com/en/products/detail/txc-corporation/7M16000024/5954370 )

I have been following https://www.youtube.com/watch?v=tj1_hsQ5PR0&t=877 to get a USB connection happening (which fails to connect).
Some images below show the circuit and i hope are useful.

CaptainJL_0-1688180514406.png CaptainJL_4-1688181100787.png

 

CaptainJL_2-1688180606611.png CaptainJL_3-1688180632042.png

 

CaptainJL_5-1688181232000.png

CaptainJL_6-1688181342774.png

CaptainJL_0-1688181615381.png

 

 

 

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AScha.3
AScha.3Best answer
Super User
July 1, 2023

as gbm said: you need a 1.5 kohm pullup to 3v3 , to start enumeration as device on usb .

and maybe - damping resistors in data lines, 22...27 ohm.

AScha3_0-1688191957917.png

 

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3 replies

gbm
gbm
Super User
July 1, 2023

1. Use the debugger to check if HSE has initialized correctly (osc status).

2, Make sure that you have a 1.5 pull-up resistor on DP.

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice
    AScha.3
    AScha.3Best answer
    Super User
    July 1, 2023

    as gbm said: you need a 1.5 kohm pullup to 3v3 , to start enumeration as device on usb .

    and maybe - damping resistors in data lines, 22...27 ohm.

    AScha3_0-1688191957917.png

     

    If you feel a post has answered your question, please click on " Best Answer ".
      CaptainJLAuthor
      Associate
      July 1, 2023

      Ah thanks guys. The 1.5k pullup on DP fixed it!

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