I’m using `HAL_UART_Transmit_IT` in two places with the Nucleo F303RE board. In `HAL_UART_RxCpltCallback`, I use it to echo received UART data, and it works fine.
In `Print_CAN_Frame`, I send messages every 3 seconds. Previously, I used `HAL_UART_Transmit`, which worked, but after switching to `HAL_UART_Transmit_IT`, I get garbled characters in TeraTerm. Both functions use the same UART configuration: BaudRate 115200, WordLength 8B, StopBits 1, Parity None, TX/RX Mode.
The issue appears only with interrupt-driven transmission. What could be causing this behavior, considering both functions take identical arguments, and how should I handle potential buffer or timing issues?

Here is my code file;