STM32CubeMX Pin Re-assignment on STM32U5A9 - Questions

[DenzilDexter]

Hello Forum,

I've noticed a feature/bug/behaviour in CubeMX 6.15.0 that I'm unsure about so could do with some advice.  I've been configuring an STM32U5A9ZJT 144 pin MCU for a project I'm working on.  This has been an evolutionary process.  To make the point I'll just focus on two peripherals, LPUART1 which has already been configured and I2C3 that I want to add in and configure.

I start with LPUART1 configured as follows:

Which has pins assigned like this on the MCU:

I then enable the previously disabled I2C3 peripheral - there's nothing to say it conflicts with anything.  This results in I2C3 looking like:

Having done this CubeMX silently reconfigured the LPUART1 pins.  

thus:

So the question is: "Is this normal?" If so I've never noticed before. It seems odd to me as I could have had a physical board made with the LPUART1 pins setup in the initial config.  Adding the I2C3 peripheral breaks LPUART1.

Any thoughts/advice much appreciated.

DD

 

 

 

 

 

 

[TDK]

It's normal as CubeMX will try its best to find pins for every peripheral as you enable them. In this case, one of those pins was likely needed for the new peripheral.

If you don't want a pin to change, lock it (right click -> Signal Pinning or Pin Locking). Then it won't be reassigned (and may prevent some peripherals from being enabled).

 

If you're still having issues, attach the IOC file just before the change is made and I'll take a look.

[DenzilDexter]

@TDK Thanks very much.