Arduino for STM32

It's my first time in this place and I'm not that familiar with everything, so please forgive me if I ask stupid questions.
I have an HMI, Arduino Uno, stm32, and blue pill, the default interface of my HMI is RS232, I need to solder it to TTL interface when I use Arduino Uno, and when I use stm32 I need to convert it to RS232 or change the level by code.
So do I need to pay attention to this when I use the blue pill?

This is a schematic of the connection to the Arduino.

normally stm32 interface ok to 5v ttl levels, so far lcds i tried work.
important thing is some stm32 pins (those adc pins pa0-pa7) are not 5v tolerant so just make sure that the lcd side is input only (i.e. high z), this is so that the lcd won't push a 5v into stm32 at those pins

ag123 wrote: Tue Jul 06, 2021 7:15 am normally stm32 interface ok to 5v ttl levels, so far lcds i tried work.
important thing is some stm32 pins (those adc pins pa0-pa7) are not 5v tolerant so just make sure that the lcd side is input only (i.e. high z), this is so that the lcd won't push a 5v into stm32 at those pins

Ok, thanks for your reply, I will pay special attention to it.