AT90PWM216-16SE ATMEL [ATMEL Corporation], AT90PWM216-16SE Datasheet - Page 208

• Manufacturer Part Number: AT90PWM216-16SE
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable flash
• Manufacturer: ATMEL [ATMEL Corporation]

18.10.5
208
AT90PWM216/316
USART Baud Rate Registers – UBRRL and UBRRH
• Bit 2:1 – UCSZ1:0: Character Size
The UCSZ1:0 bits combined with the UCSZ2 bit in UCSRB sets the number of data bits (Char-
acter SiZe) in a frame the Receiver and Transmitter use.
Table 18-7.
When the EUSART mode is set, these bits have no effect.
• Bit 0 – UCPOL: Clock Polarity
This bit is used for synchronous mode only. Write this bit to zero when asynchronous mode is
used. The UCPOL bit sets the relationship between data output change and data input sample,
and the synchronous clock (XCK).
Table 18-8.
• Bit 15:12 – Reserved Bits
These bits are reserved for future use. For compatibility with future devices, these bit must be
written to zero when UBRRH is written.
• Bit 11:0 – UBRR11:0: USART Baud Rate Register
This is a 12-bit register which contains the USART baud rate. The UBRRH contains the four
most significant bits, and the UBRRL contains the eight least significant bits of the USART baud
rate. Ongoing transmissions by the Transmitter and Receiver will be corrupted if the baud rate is
changed. Writing UBRRL will trigger an immediate update of the baud rate prescaler.
Bit
Read/Write
Initial Value
UCPOL
0
1
UCSZ2
0
0
0
0
1
1
1
1
UCSZ Bits Settings
UCPOL Bit Settings
Transmitted Data Changed
(Output of TxDn Pin)
Rising XCK Edge
Falling XCK Edge
R/W
15
R
–
7
0
0
R/W
14
R
–
6
0
0
UCSZ1
0
0
1
1
0
0
1
1
R/W
13
R
–
5
0
0
R/W
12
R
–
4
0
0
UBRR[7:0]
UCSZ0
0
1
0
1
0
1
0
1
R/W
R/W
11
3
0
0
Received Data Sampled
(Input on RxD Pin)
Falling XCK Edge
Rising XCK Edge
R/W
R/W
Character Size
5-bit
6-bit
7-bit
8-bit
Reserved
Reserved
Reserved
9-bit
10
2
0
0
UBRR[11:8]
R/W
R/W
9
1
0
0
R/W
R/W
8
0
0
0
7710D–AVR–08/09
UBRRH
UBRRL