ST STM32G4 Series Reference Manual page 1612

Universal synchronous/asynchronous receiver transmitter (USART/UART)
Bits 31:24 ADD[7:0]: Address of the USART node
ADD[7:4]:
These bits give the address of the USART node or a character code to be recognized.
They are used to wake up the MCU with 7-bit address mark detection in multiprocessor
communication during Mute mode or low-power mode. The MSB of the character sent by the
transmitter should be equal to 1. They can also be used for character detection during normal
reception, Mute mode inactive (for example, end of block detection in ModBus protocol). In this
case, the whole received character (8-bit) is compared to the ADD[7:0] value and CMF flag is set on
match.
These bits can only be written when reception is disabled (RE = 0) or the USART is disabled
(UE=0).
ADD[3:0]:
These bits give the address of the USART node or a character code to be recognized.
They are used for wakeup with address mark detection, in multiprocessor communication during
Mute mode or low-power mode.
These bits can only be written when reception is disabled (RE = 0) or the USART is disabled
(UE=0).
Bit 23 RTOEN: Receiver timeout enable
This bit is set and cleared by software.
0: Receiver timeout feature disabled.
1: Receiver timeout feature enabled.
When this feature is enabled, the RTOF flag in the USART_ISR register is set if the RX line is idle
(no reception) for the duration programmed in the RTOR (receiver timeout register).
Note: If the USART does not support the Receiver timeout feature, this bit is reserved and must be
kept at reset value. Refer to
Bits 22:21 ABRMOD[1:0]: Auto baud rate mode
These bits are set and cleared by software.
00: Measurement of the start bit is used to detect the baud rate.
01: Falling edge to falling edge measurement (the received frame must start with a single bit = 1 ->
Frame = Start10xxxxxx)
10: 0x7F frame detection.
11: 0x55 frame detection
This bitfield can only be written when ABREN = 0 or the USART is disabled (UE=0).
Note: If DATAINV=1 and/or MSBFIRST=1 the patterns must be the same on the line, for example
0xAA for MSBFIRST)
If the USART does not support the auto baud rate feature, this bit is reserved and must be kept
at reset value. Refer to
Bit 20 ABREN: Auto baud rate enable
This bit is set and cleared by software.
0: Auto baud rate detection is disabled.
1: Auto baud rate detection is enabled.
Note: If the USART does not support the auto baud rate feature, this bit is reserved and must be kept
at reset value. Refer to
Bit 19 MSBFIRST: Most significant bit first
This bit is set and cleared by software.
0: data is transmitted/received with data bit 0 first, following the start bit.
1: data is transmitted/received with the MSB (bit 7/8) first, following the start bit.
This bitfield can only be written when the USART is disabled (UE=0).
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Section 36.4: USART implementation on page
Section 36.4: USART implementation on page
Section 36.4: USART implementation on page
RM0440 Rev 1
RM0440
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