Pin Assignment Issues on STM32H745 with Ethernet, QSPI, and LCD

[RafaelS]

Hello! I'm creating my own board based on the STM32H745I-DISCO board. I want to use the LQFP208 package of the STM32H745, which has fewer pins than the original package of the DISCO board. I need to connect Ethernet, a display, and QSPI, among other peripherals.

I've encountered a conflict where the LCD_DE pin connects to PF10, which is also used by the QSPI_CLK pin. I saw that QSPI_CLK is also available on PB2. However, PB2 is occupied by MII_TX_ERR/nINT

.

My question arises when I notice that this pin is not defined in the Ethernet configuration in MXCube (I'm new to the CubeIDE environment and ST's frameworks, and I'm worried I might be missing something). In fact, I disconnected this pin between the Ethernet driver and the STM32H745, and communication with a test server still works.

So my question is: Is it really a good idea to leave the MIIMII_TX_ERR/nINT pin unconnected? Could it be that communication works for now, but if some kind of error occurs, it could cause problems?

Thanks, best regards!

[TDK · Accepted solution]

ETH_TX_ERR is optional for MII and doesn't exist at all for RMII.

LCD_DE is available on PE13. Should be able to have all 3 peripherals active, including TX_ERR if you want it, without conflicts.