Pixhawk 4 tolerant to 5v logic level instead of 3.3v?


I have a sensor that sends serial data between 0 and 5v and not 0 and 3.3v.
Are pixhawk 4 serial ports(TELEM1-2/I2c&UART) RX/TX lines tolerants to this 5v logic or do I need to use a level shifter for that?

Best regards,


I hope @david_s5 can answer this question.

It is dependent on which pins. In general 166 of IOs are 5 Volt tolerant.

I2C may be an issue due levels and the pull ups on the FMU are to the 3.3V supply.

Please See https://docs.google.com/spreadsheets/d/1-n0__BYDedQrc_2NHqBenG1DNepAgnHpSGglke-QQwY/edit#gid=912976165

On the All pinouts Page you will find the signals. Next to the signals is the port and pin. Then look that up in the https://www.st.com/resource/en/datasheet/stm32f765bg.pdf

FT indicates 5 V tolerant I/O

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Thanks for the support @david_s5!

Just double checking:
for the RX of the serial port called “UART&I2C B” on pixhawk 4, so /dev/ttyS3

  • Pin name = PD0

  • I/O structure = FT

So I can input a 5V logic without risk.

Best regards,


Yes it is ttyS3 and yes it is 5 Volt tolerent.

Hello, I’m a little late.
Can all STM32F765-based Pixhawks be seen on that spreadsheet? To determine if they are tolerant?
I have a PX4 from Holybro: Pixhawk 4 | PX4 User Guide

And I need to connect the telemetry radio that has telemetry outputs with 5V TX RTS. I wanted to know if it was possible.

Thank you!