I do have STM32F072RB microcontroller which works on 5V but also have output power pins on 3.3V.
I do have Wi-Fi module (ESP 8226) that works on 3.3V. I can power it with STM easily but what about UART pins? Will they switch themselves to 3.3V and work properly? When not, how do I connect RX and TX busses so they can work properly?