Higher GPIO control than VDD

[Novice.LEE]

Hello.

I use STM32G071GBU6, and I designed the VDD voltage to use 1.8V.

I have some questions on the board.

1. 3.3V GPIO OUTPUT CONTROL

- Should I set the GPIO pin of the MCU to open drain and connect it?

2. 3.3 Volt UART Communication ( TX,RX)

- Should I set the UART pin of the MCU to open drain and connect it?

2.5 V GPIO Control

- Should I set the GPIO pin with 5 V tolerant as an open drain and connect it?

If the above method is not correct, please suggest a good method.

Thank you.

[Novice.LEE]

[S.Ma · Accepted solution]

If the power voltage is 1.8V, mcu pin can drive 1.8v. If you want a higher voltage because the other device is not compatible with 1.8v, then use open drain up to 5V with external pull up resistor. Rise edge will depend on resistor (consumption). Speed maybe limited. Full 1.8V system example could be your smartphone....