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Associate
September 8, 2025
Question

STM32U375RGT6Q - UART function

  • September 8, 2025
  • 6 replies
  • 449 views

Hi,

Will PC0 PC1 LPUART functions in normal operation? 

I have to use this LPUART in normal operation of MCU, not in power saving mode.

Is there any limitation on this like speed, baud rate etc. 

Regards,

Anurag

 

 

 

 

6 replies

Shirley.Ye
ST Employee
September 8, 2025

ShirleyYe_0-1757315614017.png

from the reference manual, it can reach higher frequence if clock sources different from the LSE clock

Jojo_
ST Employee
September 8, 2025

Hello,

Just one point to add: the latest cube firmware for STM32U3 contains a working example of LPUART communication, without any low power modes.

The example "LPUART_TwoBoards_ComIT" can be found by navigating the example selector in STM32CubeMX.

It could serve as a good starting point to test if the LPUART fits your intended use case.

Associate
September 11, 2025

Hi,

We are using STM32U375RGT6Q.

Power 2.5V

When internal oscillator used 4MHz, it takes less power, less than 0.5mA.

When shift to external oscillator 4MHz, internal used clock 2MHz, it takes more power, greater than 1.5mA.

We have to use external oscillator for measurement accuracy. 

We have to reduce the MCU current on 2.5V with external oscillator, crystal used.

Can you suggest possible ways to reduce power consumption.

Input voltage for device is 5V 1mA. Used buck converter for 2.5V 85% efficiency. 

Regards,

Anurag

 

 

 

 

 

Associate
September 15, 2025

Hi,

Can we use 2MHz external crystal for STM32U375RGT6Q? for low power consumption. 

Though it is not given in datasheet.

 

Regards,

Anurag

 

gbm
Principal
September 15, 2025

If low power is a concern, why don't you use MSI internal oscillator synchronized to LSE?

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice
Associate
September 17, 2025

Hi,

Thanks!

Does this solution has impact of temperature on accuracy? 

Or it has nearly accuracy of LSE external crystal?

 

gbm
Principal
September 17, 2025

It has exactly the accuracy of the 32768 Hz crystal. Why don't you read the RCC section of RefMan?

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice