Arduino for STM32

The scanner works on I2C2 means that your HW connection is OK. Which library do you use for the ADS chip? It is not enough to initialize the interface in setup, you should somehow tell the lib that you are not using the "standard" interface I2C 1, but I2C 2. Otherwise the lib will continue...

The HID bootloader should work, what you see is that the bootloader did jump to application code which is, in this case, corrupted. You should set BOOT1 pin to 1 with the jumper, press reset, then the bootloader waits for upload command over USB. Use a blinky sketch with USB serial, so that after yo...

It should work.
If it doesn't then let us know.

HardWire on PB6/7 uses the harware I2C interface.
For SoftWire you can define your own pins.

Which block diagram do you refer to?
How did you manage to use USART1 on PB6/7?
Please always post links/code, otherwise we cannot read your thoughts.
PA9/10 are usually TX1, RX1.
PA11/12 are USB pins.

viewtopic.php?f=2&t=301
Which core do you use?

viewtopic.php?f=2&t=301
Which core do you use?

viewtopic.php?f=2&t=301
Which core do you use?
Have you tried other I2C modules?

And what exactly is your problem? Which step is not working?