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How to design USB for STM32F105VCT6

WPong.1
Associate II

Hi All,

I want to design USB schematic for STM32F105VCT6. I read Introduction to USB hardware and PCB guidelines using STM32 MCUs(AN4879) and it said that STM32F105/STM32F107 has Pull-up resistor on USB_DP line.

Question 1

Can I design USB schematic with no Pull-up resistor on USB_DP? And no need any config about embedded Pull-up resistor in software?

Question 2

Should I put some resistor between USB connector and STM32F105 on both USB D+,D- ? If yes, what value should add.

This is example schematic from stm32 bluepill. I saw there are resistor between USB connector and STM32F103

Capture.PNG

 

Thank you for your answer

1 ACCEPTED SOLUTION

Accepted Solutions

Dear @WPong.1 ,

 

Here you go :

https://www.st.com/resource/en/datasheet/stm32f107vc.pdf#page95

No need for Serial resistance neither the pull-up . You need to connect D-, D+ and VBus to the connector , in case of your device is bus powered that means all power from VBus : 5volts from Host , in case of Host follow the recommendation as well.

IMG_9740.jpeg

 Hope it helps ,

STOne-32

View solution in original post

4 REPLIES 4
AScha.3
Chief II

Hi,

see ds:

AScha3_0-1727599907897.png

-> no need for any external resistor .

(and dont ever use pullup to +5V ! Thats just wrong. USB has 3v3 signal levels...! )

+ only (old) F103 needs 1k5 pullup to 3v3 .

If you feel a post has answered your question, please click "Accept as Solution".

What is HNP/SNP/IP ?

Dear @WPong.1 ,

 

Here you go :

https://www.st.com/resource/en/datasheet/stm32f107vc.pdf#page95

No need for Serial resistance neither the pull-up . You need to connect D-, D+ and VBus to the connector , in case of your device is bus powered that means all power from VBus : 5volts from Host , in case of Host follow the recommendation as well.

IMG_9740.jpeg

 Hope it helps ,

STOne-32

Thank you for your answer. I found that in STM32CubeMX, I did not select Activate VBUS so it made embedded pull-up resistor not pull to signal full-speed peripheral connections then PC and STM32 device are not communicate together(No COM Port available [I use USB CDC class]).

 

After solve the problem I have read reference manual again and found that "DP/DM integrated pull-up and pull-down resistors controlled by the OTG_FS core depending on the current role of the device. As a peripheral, it enables the DP pull-up resistor to signal full-speed peripheral connections as soon as VBUS is sensed to be at a valid level (B-session valid)."

that is reason why if I select Activate VBUS in STM32CubeMX, USB CDC work properly.

 

Thank for your help again.

 

Screenshot 2024-09-29 191809.png