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Pavel A.
Pavel A.
Super User
March 6, 2018
Solved

STM32F446 - why PB12 conflicts with USB PHY?

  • March 6, 2018
  • 1 reply
  • 2457 views
Posted on March 07, 2018 at 00:16

Why CubeMX 4.24 says that PB12 conflicts with USB_OTG_HS when external HS PHY is not is use?

The MCU is F446ZCT, its USB HS core is in FS, host only mode, Activate_SOF and Activate_VBUS unchecked.

PB12 can have two alternate functions for USB HS core - but both are related only to HS mode, correct?

So why conflict with the PHY in FS internal PHY mode?

(and, by the way, what does ''Activate_VBUS'' in host mode? I use a different output pin to switch VBUS to the port).

Thanks,

-- pavel

0690X00000609y0QAA.png

#usb-fs #cubemx-v4.24
This topic has been closed for replies.
Best answer by Khouloud GARSI
Posted on March 07, 2018 at 18:53

Hi

pavel_a

‌,

On the datasheet, we are mentioning that the STM32F446 MCU have:

  • USB 2.0 full-speed device/host/OTG controller with on-chip PHY : (OTG1_FS through GPIOA ).

  • USB 2.0 high-speed/full-speed device/host/OTG controller with dedicated DMA, on-chip full-speed PHY (OTG2_FS through GPIOB) and ULPI (OTG2_HS).

If you are using the second on chip FS PHY (GPIOB), the related pins are described as HS because they are linked to the USB 2.0 high-speed/full-speed device/host/OTG controller.

On the datasheet, you may notice that the PB12 is the OTG_HS_ID in the OTG2_FS peripheral.

You may also notice that also PB14 and PB15 are mentioned as ''USB_OTG_

H

S_DM'' and ''USB_OTG_

H

S_DP''.

0690X00000609zlQAA.png

Thus, the if you are using the USB FS PHY through the GPIOB port, the PB12 should not be used by another peripheral.

Khouloud.

1 reply

Khouloud GARSI
Khouloud GARSIAnswer
Technical Moderator
March 7, 2018
Posted on March 07, 2018 at 18:53

Hi

pavel_a

‌,

On the datasheet, we are mentioning that the STM32F446 MCU have:

  • USB 2.0 full-speed device/host/OTG controller with on-chip PHY : (OTG1_FS through GPIOA ).

  • USB 2.0 high-speed/full-speed device/host/OTG controller with dedicated DMA, on-chip full-speed PHY (OTG2_FS through GPIOB) and ULPI (OTG2_HS).

If you are using the second on chip FS PHY (GPIOB), the related pins are described as HS because they are linked to the USB 2.0 high-speed/full-speed device/host/OTG controller.

On the datasheet, you may notice that the PB12 is the OTG_HS_ID in the OTG2_FS peripheral.

You may also notice that also PB14 and PB15 are mentioned as ''USB_OTG_

H

S_DM'' and ''USB_OTG_

H

S_DP''.

0690X00000609zlQAA.png

Thus, the if you are using the USB FS PHY through the GPIOB port, the PB12 should not be used by another peripheral.

Khouloud.

Pavel A.
Pavel A.Author
Super User
March 7, 2018
Posted on March 07, 2018 at 22:12

Thank you,  Khouloud

-- pa

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