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yaxsomo
Explorer II
September 1, 2024
Solved

STM32H7 and USB-C Schematics

  • September 1, 2024
  • 2 replies
  • 4746 views

Hello everyone! 

I'm close to validating all my schematics for a PCB project, and I wanted to be sure at 100% that a section is correct.

I'm talink about the USB-C section, that connects directly to the STM32H7 microcontroller. 

yaxsomo_0-1725199609003.png

It will be used to access a NAND Flash Memory that is connected via SDMMC 4 Bits Wide Bus directly to the STM32 : 

yaxsomo_1-1725199696063.png

 

Can you please tell me if there's an error? 
I also saw that in some designs they connect the CC1 and CC2 pins to a 5.1k resistor each, do I have to do the same for this design?
I'm also confused about the 22 Ohms termination resistors. I saw countless forums and discussions where some people say they're necessary and other people say they're not. What's the recommendation for an STM32H7A3VIT6 microcontroller (Full Speed 12.2Mbps)?

    This topic has been closed for replies.
    Best answer by BarryWhit

    The spec tells you to either connect the CC lines to a USB-PD controller, or put the 5.1Kohm pulldowns on them.

    If you don't, you're a bad person and your device will only get power if connected to an old style type-A USB port via a type-A to type-C cable.

    Beware that if the user connects your device to an unpowered USB 2.0 hub, it may only be allowed to draw 100mA of current max. Since the H7 is a power-hungry series, you should make sure you're not drawing more power than allowed. Powered ports will give you at least 500mA (and up to 1.5A), but you can't control what your user will connect to so you should plan ahead for that.

    2 replies

    Y
    yaxsomoAuthor
    Explorer II
    September 1, 2024

    > I'm also confused about the 22 Ohms termination resistors. I saw countless forums and discussions where some people say they're necessary and other people say they're not. What's the recommendation for an STM32H7A3VIT6 microcontroller (Full Speed 12.2Mbps)?

    For this question I have my answer :) :

    yaxsomo_0-1725201496414.png

     

      B
      BarryWhitAnswer
      Graduate II
      September 1, 2024

      The spec tells you to either connect the CC lines to a USB-PD controller, or put the 5.1Kohm pulldowns on them.

      If you don't, you're a bad person and your device will only get power if connected to an old style type-A USB port via a type-A to type-C cable.

      Beware that if the user connects your device to an unpowered USB 2.0 hub, it may only be allowed to draw 100mA of current max. Since the H7 is a power-hungry series, you should make sure you're not drawing more power than allowed. Powered ports will give you at least 500mA (and up to 1.5A), but you can't control what your user will connect to so you should plan ahead for that.

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