Rainbow Electronics ATmega32L - Manual (Page 160)

160
ATmega32(L)
2503C–AVR–10/02
do not contain data to be transmitted. When disabled, the transmitter will no longer over-
ride the TxD port.
• 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.
• 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.
• Bit 0 – TXB8: Transmit Data Bit 8
TXB8 is the ninth data bit in the character to be transmitted when operating with serial
frames with nine data bits. Must be written before writing the low bits to UDR.
USART Control and Status
Register C – UCSRC
The UCSRC Register shares the same I/O location as the UBRRH Register. See the
“Accessing UBRRH/ UCSRC Registers” on page 156 section which describes how to
access this register.
• Bit 7 – URSEL: Register Select
This bit selects between accessing the UCSRC or the UBRRH Register. It is read as
one when reading UCSRC. The URSEL must be one when writing the UCSRC.
• Bit 6 – UMSEL: USART Mode Select
This bit selects between Asynchronous and Synchronous mode of operation.
Bit 7 6 5 4 3 2 1 0
URSEL UMSEL UPM1 UPM0 USBS UCSZ1 UCSZ0 UCPOL UCSRC
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 1 0 0 0 0 1 1 0
Table 63. UMSEL Bit Settings
UMSEL Mode
0 Asynchronous Operation
1 Synchronous Operation