Refer to STM’s data sheet for detail alternate function of each pin out.

1.SWD (ST-Link V2)

https://my.st.com/content/my_st_com/en/products/development-tools/hardware-development-tools/development-tool-hardware-for-mcus/debug-hardware-for-mcus/debug-hardware-for-stm32-mcus/st-link-v2.html

2.UART IAP

Refert to AN4657  https://my.st.com/resource/en/application_note/dm00161366.pdf

3. Boot ROM

Refert to AN2606  https://my.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf

AI127x-xxxH series provides I2C, PWM, SPI, GPIO, UART and auxiliary ADC.