Table 197. Effect Of Low-Power Modes On The Usart; Table 198. Usart Interrupt Requests - ST STM32L4x6 Reference Manual

Universal synchronous asynchronous receiver transmitter (USART)
36.6 USART low-power modes
Sleep
Low-power run
Low-power sleep
Stop 0 / Stop 1
Stop 2
Standby
Shutdown
36.7 USART interrupts
Transmit data register empty
CTS interrupt
Transmission Complete
Receive data register not empty (data ready to be read)
Overrun error detected
Idle line detected
Parity error
LIN break
Noise Flag, Overrun error and Framing Error in multibuffer
communication.
Character match
Receiver timeout
End of Block
Wakeup from Stop mode
1. The WUF interrupt is active only in Stop mode.
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Table 197. Effect of low-power modes on the USART

Mode
No effect. USART interrupt causes the device to exit Sleep mode.
No effect.
No effect. USART interrupt causes the device to exit Low-power sleep
mode.
The USART registers content is kept. The USART is able to wake up the
MCU from Stop 0 and Stop 1 modes when the UESM bit is set and the
USART clock is set to HSI16 or LSE.
The MCU wakeup from Stop 0 and Stop 1 modes can be done using either
a standard RXNE or a WUF interrupt.
The USART registers content is kept. The USART must either be disabled
or put in reset state.
The USART is powered down and must be reinitialized when the device
has exited from Standby or Shutdown mode.

Table 198. USART interrupt requests

Interrupt event
DocID024597 Rev 3
Description
Event flag
TXE
CTSIF
TC
RXNE
ORE
IDLE
PE
LBDF
NF or ORE or FE
CMF
RTOF
EOBF
(1)
WUF
RM0351
Enable Control
bit
TXEIE
CTSIE
TCIE
RXNEIE
IDLEIE
PEIE
LBDIE
EIE
CMIE
RTOIE
EOBIE
WUFIE