ATA6613 ATMEL Corporation, ATA6613 Datasheet - Page 217

• Manufacturer Part Number: ATA6613
• Description: Ata6613
• Manufacturer: ATMEL Corporation

6.17.9.5
6.17.10
9111C–AUTO–02/08
Examples of Baud Rate Setting
USART Baud Rate Registers – UBRRnL and UBRRnH
For standard crystal and resonator frequencies, the most commonly used baud rates for asyn-
chronous operation can be generated by using the UBRRn settings in
UBRRn values which yield an actual baud rate differing less than 0.5% from the target baud
rate, are bold in the table. Higher error ratings are acceptable, but the Receiver will have less
noise resistance when the error ratings are high, especially for large serial frames (see
chronous Operational Range” on page
equation:
Error[%]
• Bit 15:12 – Reserved Bits
• Bit 11:0 – UBRR11:0: USART Baud Rate Register
Initial Value
Read/Write
These bits are reserved for future use. For compatibility with future devices, these bit must
be written to zero when UBRRnH is written.
This is a 12-bit register which contains the USART baud rate. The UBRRnH contains the
four most significant bits, and the UBRRnL 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 UBRRnL will trigger an immediate update of the baud
rate prescaler.
Bit
=
BaudRate
------------------------------------------------------- - 1
R/W
BaudRate
15
R
–
7
0
0
Closest Match
R/W
14
R
–
6
0
0
–
R/W
13
R
–
5
0
0
100%
210). The error values are calculated using the following
R/W
12
UBRRn[7:0]
R
–
4
0
0
R/W
R/W
11
3
0
0
ATA6612/ATA6613
R/W
R/W
10
UBRRn[11:8]
2
0
0
R/W
R/W
Table 6-79 on page
9
1
0
0
R/W
R/W
8
0
0
0
UBRRnH
UBRRnL
“Asyn-
218.
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