ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 189

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

USART Control and Status
Register C – UCSRC
2490G–AVR–03/04
(1)
do not contain data to be transmitted. When disabled, the Transmitter will no longer
override 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.
Note:
• Bit 7 – Reserved Bit
This bit is reserved for future use. For compatibility with future devices, this bit must be
written to zero when UCSRC is written.
• Bit 6 – UMSEL: USART Mode Select
This bit selects between asynchronous and synchronous mode of operation.
Table 77. UMSEL Bit Settings
• Bit 5:4 – UPM1:0: Parity Mode
These bits enable and set type of parity generation and check. If enabled, the Transmit-
ter will automatically generate and send the parity of the transmitted data bits within
each frame. The Receiver will generate a parity value for the incoming data and com-
pare it to the UPM0 setting. If a mismatch is detected, the UPE flag in UCSRB will be
set.
Table 78. UPM Bits Settings
Bit
Read/Write
Initial Value
UPM1
1. This register is not available in ATmega103 compatibility mode.
UMSEL
0
0
1
1
0
1
R/W
7
–
0
UMSEL
R/W
6
0
UPM0
Mode
Asynchronous Operation
Synchronous Operation
0
1
0
1
UPM1
R/W
5
0
UPM0
R/W
Parity Mode
Disabled
Reserved
Enabled, Even Parity
Enabled, Odd Parity
4
0
USBS
R/W
3
0
UCSZ1
R/W
2
1
ATmega64(L)
UCSZ0
R/W
1
1
UCPOL
R/W
0
0
UCSRC
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