STM32G474 - ROM bootloader puts I2C on non-existent pins for LQFP48?

[anotherandrew]

I am designing a product with an STM32G474CET (LQFP48 package) and would like to use the ROM bootloader with I2C; looking at AN2606 section 48.1, I see that I must use I2C2, I2C3 or I2C4 if I want to use the ROM bootloader.

This is fine, but according to AN2606 it looks like the bootloader puts these peripherals on pins that don't actually exist on the LQFP48 package:

• I2C2: SCL on PC4, SDA on PA8 - PC4 does not exist on this package
• I2C3: SCL on PC8, SDA on PC9 - neither pin exists on this package
• I2C4: SCL on PC6, SDA on PC7 - neither pin exists on this package

Is this a documentation omission or error (i.e. does the ROM bootloader map to pins that exist on smaller packages), or is the I2C bootloader not available for the STM32G474C in LQFP48?

[STTwo-32 · Accepted solution]

Hello @anotherandrew 

If the mentioned pins on the AN2606 does not exist on the Package that you are using, then this package does not support the bootloader on the Concerned API (I2C,UART ...). This is exactly the same case that you are toking about here. So, you have to use another API that have the necessary pins available for this configuration (usart1 for example).

Best Regards.

STTwo-32

[anotherandrew]

Thank you. Sadly not the answer I was hoping for, but understandable.