Welcome to the forum.
Please see How to write your question to maximize your chances to find a solution for best results.
In particular, please give details of your hardware, your code, and what tools you're using.
@pari wrote:
the STM32 fails to receive data correctly. .
What does that mean, exactly: it receives nothing? receives junk? receives partial data? other?
How are you sure that your Arduino is transmitting correctly?
It's generally better to test against a terminal on a PC - then you remove all the unknowns of your code on the Arduino.
@pari wrote:
I'm looking for a reliable solution to ensure proper UART communication in this configuration.
A common approach is to have the UART receive under interrupt to a ring buffer, and your main loop processes the data from that buffer. (this is what the Arduino does internally).
PS:
There's a bit more detail here of how the Arduino Serial works "under the hood" - including use of interrupts & ring buffers.
A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.
