193
AT90PWM216/316 [DATASHEET]
7710H–AVR–07/2013
17.10.3
USART Control and Status Register B – UCSRB
Bit 7 – RXCIE: RX Complete Interrupt Enable
Writing this bit to one enables interrupt on the RXC flag. A USART Receive Complete interrupt will be generated
only if the RXCIE bit is written to one, the Global Interrupt Flag in SREG is written to one and the RXC bit in
UCSRA is set.
This bit is available for both USART and EUSART modes.
Bit 6 – TXCIE: TX Complete Interrupt Enable
Writing this bit to one enables interrupt on the TXC flag. A USART Transmit Complete interrupt will be generated
only if the TXCIE bit is written to one, the Global Interrupt Flag in SREG is written to one and the TXC bit in UCSRA
is set.
This bit is available for both USART and EUSART mode.
Bit 5 – UDRIE: USART Data Register Empty Interrupt Enable
Writing this bit to one enables interrupt on the UDRE flag. A Data Register Empty interrupt will be generated only if
the UDRIE bit is written to one, the Global Interrupt Flag in SREG is written to one and the UDRE bit in UCSRA is
set.
This bit is available for both USART and EUSART mode.
Bit 4 – RXEN: Receiver Enable
Writing this bit to one enables the USART Receiver. The Receiver will override normal port operation for the RxD
pin when enabled. Disabling the Receiver will flush the receive buffer invalidating the FE, DOR, and UPE Flags.
This bit is available for both USART and EUSART mode.
Bit 3 – TXEN: Transmitter Enable
Writing this bit to one enables the USART Transmitter. The Transmitter will override normal port operation for the
TxDn pin when enabled. The disabling of the Transmitter (writing TXEN to zero) will not become effective until
ongoing and pending transmissions are completed, i.e., when the Transmit Shift Register and Transmit Buffer Reg-
ister do not contain data to be transmitted. When disabled, the Transmitter will no longer override the TxDn port.
This bit is available for both USART and EUSART mode.
Bit 2 – UCSZ2: Character Size
The UCSZ2 bits combined with the UCSZ1:0 bit in UCSRC sets the number of data bits (Character SiZe) in a
frame the Receiver and Transmitter use.
This bit have no effect when the EUSART mode is enabled.
Bit 1 – RXB8: Receive Data Bit 8
RXB8 is the ninth data bit of the received character when operating with serial frames with nine data bits. Must be
read before reading the low bits from UDR.
When the EUSART mode is enable and configured in 17 bits receive mode, this bit contains the seventeenth bit
(see EUSART section).
Bit
76543210
RXCIE
TXCIE
UDRIE
RXEN
TXEN
UCSZ2
RXB8
TXB8
UCSRB
Read/Write
R/W
R
R/W
Initial Value
00000000