ST STM32F102 Series Reference Manual page 643

RM0008
Bit 6 TCIE: Transmission Complete Interrupt Enable.
This bit is set and cleared by software.
0: Interrupt is inhibited
1: An USART interrupt is generated whenever TC=1 in the USART_SR register
Bit 5 RXNEIE: RXNE Interrupt Enable.
This bit is set and cleared by software.
0: Interrupt is inhibited
1: An USART interrupt is generated whenever ORE=1 or RXNE=1 in the USART_SR register
Bit 4 IDLEIE: IDLE Interrupt Enable.
This bit is set and cleared by software.
0: Interrupt is inhibited
1: An USART interrupt is generated whenever IDLE=1 in the USART_SR register
Bit 3 TE: Transmitter Enable.
This bit enables the transmitter. It is set and cleared by software.
0: Transmitter is disabled
1: Transmitter is enabled
Notes:
1: During transmission, a "0" pulse on the TE bit ("0" followed by "1") sends a preamble (idle line) after
the current word, except in smartcard mode.
2: When TE is set there is a 1 bit-time delay before the transmission starts.
Bit 2 RE: Receiver Enable.
This bit enables the receiver. It is set and cleared by software.
0: Receiver is disabled
1: Receiver is enabled and begins searching for a start bit
Bit 1 RWU: Receiver wakeup.
This bit determines if the USART is in mute mode or not. It is set and cleared by software and can
be cleared by hardware when a wakeup sequence is recognized.
0: Receiver in active mode
1: Receiver in mute mode
Notes:
1: Before selecting Mute mode (by setting the RWU bit) the USART must first receive a data byte,
otherwise it cannot function in Mute mode with wakeup by Idle line detection.
2: In Address Mark Detection wakeup configuration (WAKE bit=1) the RWU bit cannot be modified by
software while the RXNE bit is set.
Bit 0 SBK: Send Break.
This bit set is used to send break characters. It can be set and cleared by software. It should be set
by software, and will be reset by hardware during the stop bit of break.
0: No break character is transmitted
1: Break character will be transmitted
Universal synchronous asynchronous receiver transmitter (USART)
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