Electronic – directly interface to 5V I2C devices with an STM32 running on 1.8V


STM32 I/O pins are 5V-tolerant. I2C devices use open-drain outputs. I currently see no problem with operating an I2C bus with 5V devices from a 1.8V STM32 (with pullups to 5V). Is my understanding correct?

Best Answer

Yes. I just recently had an opportunity to test this. You must set the GPIO to Open Drain mode with no pullup but then it works fine. All of the pins that can be I2C pins are qualified to be 5V tolerant according to the ST Micro documentation.