Arduino for STM32

Hey, thanks a lot, I have been able to switch to HSI with Cube generated clock config.

Ok, so to clarify. I just found out that the default Serial.write is linked to USART2_TX on pin PA2 and Serial.read to USART2_RX on pin PA15 as Alternate function. Wire works with I2C1 pins PB6/7. This is really confusing. Is there any resource to the pin mapping on various Arduino compatible MCUs ...

Hello, it is my first post here. I have a custom board (essentially QFN32 adaptor) with STM32L412K8T6. I could program the board via USB in DFU mode, but the firmware didn't run until I soldered external crystal.
For the project I am using uart and I2C ports. I have tested the I2C on pins 29(PB6 ...