Device firmware upgrade pins in STM32F303ZET6 are USART1 (PA9/PA10), USART2 (PA2/PA3) or USB (PA11/PA12).But my external interface is UART. Can i able to configure the USART pins as UART?

[gbm]

USART is UART. You don't need to configure anything. The bootloader works out of the box.

[waclawek.jan]

> USART is UART

... with synchronous capability (hence the S), which is not used in the bootloader, as gbm said above.

JW

[Tesla DeLorean]

The ROM supports what it supports, the functionality described in AN2606 is what is available, and the pins it uses.

The protocol uses asynchronous 8E1 serial data, it's not using synchronous modes, there is not a clock signal