STM32H743bi - use FDCAN2 and USB ULPI simultaneously?
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‎2020-06-27 12:39 PM - last edited on ‎2024-08-21 4:36 AM by Andrew Neil
Hello,
I am using Cube32MX for STM32H743bi IO multiplexing. first i added USB HS phy ULPI interface then see FDCAN2 not allowed in the tool and error message says it is in conflict with USB ULPI. However i manually checked there were certain pins for CAN2 classic and even FD available.
I want to know whether it s some bug or there is some internal MCU sharing between these two that i am unaware of. Else several options are available for FDCAN2 after consuming USB ULPI.
thnx
Solved! Go to Solution.
- Labels:
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FDCAN
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STM32CubeMX
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STM32H7 Series
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USB
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‎2020-07-02 8:48 AM
Hello HKhan.1,
As I understand you have activated USB_OTG_HS and configured the External Phy, thus:
- PB5 pin will be assigned automatically to USB_OTG_HS_ULPI_D7 .
- PB12 to OTG_HS_ULPI_D5 .
- PB13 to OTG_HS_ULPI_D6 .
and if you refer to DS12110 Rev 7 Data Sheet: OTG_HS_ULPI_D7 , OTG_HS_ULPI_D5 and OTG_HS_ULPI_D6 can’t be remapped and can only be assigned respectively to PB5 ,PB12 and PB13.
When enabling FDCAN2 two pins will be activated and backing to same reference:
- FDCAN2_RX can be assigned to either PB5 or PB12
- FDCAN2_TX can be assigned to either PB13 or PB6
Thus FDCAN2_RX can’t be assigned to any pin (since pB5 and PB12 are not available) and USB ULPI is in conflict with FDCAN2.
BR,
Khouloud.
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‎2020-06-27 12:49 PM
*STM32H743bi
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‎2020-07-02 8:48 AM
Hello HKhan.1,
As I understand you have activated USB_OTG_HS and configured the External Phy, thus:
- PB5 pin will be assigned automatically to USB_OTG_HS_ULPI_D7 .
- PB12 to OTG_HS_ULPI_D5 .
- PB13 to OTG_HS_ULPI_D6 .
and if you refer to DS12110 Rev 7 Data Sheet: OTG_HS_ULPI_D7 , OTG_HS_ULPI_D5 and OTG_HS_ULPI_D6 can’t be remapped and can only be assigned respectively to PB5 ,PB12 and PB13.
When enabling FDCAN2 two pins will be activated and backing to same reference:
- FDCAN2_RX can be assigned to either PB5 or PB12
- FDCAN2_TX can be assigned to either PB13 or PB6
Thus FDCAN2_RX can’t be assigned to any pin (since pB5 and PB12 are not available) and USB ULPI is in conflict with FDCAN2.
BR,
Khouloud.
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‎2020-07-03 7:55 AM
Thnx Khouloud, You are right. I actually confused with FDCAN2 Debug pins
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‎2023-09-24 11:33 AM
Thanks for the good explanation, but I still wonder what exactly "External Phy" means in this case? Is it a separate chip that does the USB communication at 480MBit/s? Cause for me, USB Full Speed would be enough. Can I just use the internal FS Phy and use the VCP like normal? Sorry, I'm new to STM32 development, and want to get things right before I start with the PCB...
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‎2023-09-24 11:56 AM - edited ‎2023-09-24 12:02 PM
Yes, "external" means a separate chip.
> for me, USB Full Speed would be enough. Can I just use the internal FS Phy and use the VCP like normal?
Yes, sure. See this.
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