ST STM32F102 Series Reference Manual page 647

RM0008
Bit 4 NACK: Smartcard NACK enable.
0: NACK transmission in case of parity error is disabled
1: NACK transmission during parity error is enabled.
Note: This bit is not available for UART4 & UART5.
Bit 3 HDSEL: Half-Duplex Selection.
Selection of Single-wire Half-duplex mode
0: Half duplex mode is not selected
1: Half duplex mode is selected
Bit 2 IRLP: IrDA Low-Power.
This bit is used for selecting between normal and low-power IrDA modes
0: Normal mode
1: Low-power mode
Bit 1 IREN: IrDA mode Enable.
This bit is set and cleared by software.
0: IrDA disabled
1: IrDA enabled
Bit 0 EIE: Error Interrupt Enable.
Error Interrupt Enable Bit is required to enable interrupt generation in case of a framing error,
overrun error or noise error (FE=1 or ORE=1 or NE=1 in the USART_SR register) in case of Multi
Buffer Communication (DMAR=1 in the USART_CR3 register).
0: Interrupt is inhibited
1: An interrupt is generated whenever DMAR=1 in the USART_CR3 register and FE=1 or ORE=1
or NE=1 in the USART_SR register.
Universal synchronous asynchronous receiver transmitter (USART)
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