5v Tolerant UART on STM32H753

Posted on May 30, 2018 at 17:08

Hello,

We want to connect a 5v UART device to our STM32H753 MUC through one of the 5v-tolerant UART_RX pins.

The MCU IO voltage is 1.8v.

The UART is one-directional, from the 5v device to a UART_RX pin, for example PB15.

Is there anything we need to take into account here? Is there an internal pull-up/down on pin?

Thanks in advance,

Yan

#uart-rx #5v-tolerant

This topic has been closed for replies.

Senior III

Posted on May 30, 2018 at 17:51

Do you have to use a 5V RS232 device ?

You can use a voltage divider to lower the high voltage,

or use a transistor to level shift (but it also inverts the input.)

I wonder if the excessive voltage would disturb the analog inputs. maybe.

Associate II

Posted on May 31, 2018 at 09:56

Hi TJ,

Thanks for the reply!

We have to use the 5v device, it goes only as low as 2.7v and we want to power the MCU from 1.8v.

We could use a voltage divider, but do we have to?

We want to save as much space as we can on the board, so any extra components are examined very closely

Thanks,

Yan

Senior III

Posted on May 31, 2018 at 11:57

do you need analog ? probably wont work well with 5v on some pins...

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