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Unused UART Rx pin on STM32F

krishr
Associate II

Dear All,

on my STM32F board, i have the uart rx pin not connected/floating. Due to too many noise interrupts, I have configured UART in tx mode only and disabled RX interrupts. Is this fine? Or should the internal pull up be enabled for the RX pin? 

1 ACCEPTED SOLUTION

Accepted Solutions
SofLit
ST Employee

Hello,

Simply configure UART in Tx mode only and keep the Rx pin in default state: don't configure the alternate function on this pin.

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5 REPLIES 5
SofLit
ST Employee

Hello,

Simply configure UART in Tx mode only and keep the Rx pin in default state: don't configure the alternate function on this pin.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

Another question - does it have any impact on the current consumption? Does the TX mode only enable pullups for RX  by default?

The pull-up/down resistors are managed at GPIO peripheral level not the peripheral.

To avoid extra I/O current, the pin should be configured as analog input (AIN). In this mode the Schmitt trigger input is disabled, providing zero consumption for the I/O pin.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

Thank you. Could you also explain the difference in current when enabling pull up or configuring in HiZ mode? 

Hello,

I propose you to open a new thread as this is a different topic.

Thank you.

 

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