AT90S2313-4PC View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'AT90S2313-4PC' PDF : 92 Pages View PDF
Baud Rate Generator
0839I–AVR–06/02
AT90S2313
• Bit 1 – RXB8: Receive Data Bit 8
When CHR9 is set (one), RXB8 is the ninth data bit of the received character.
• Bit 0 – TXB8: Transmit Data Bit 8
When CHR9 is set (one), TXB8 is the ninth data bit in the character to be transmitted.
The baud rate generator is a frequency divider that generates baud rates according to
the following equation:
BAUD = ---------------f--C---K----------------
16(UBRR + 1)
• BAUD = Baud Rate
• fCK = Crystal Clock frequency
• UBRR = Contents of the UART Baud Rate Register (UBRR) (0 - 255)
For standard crystal frequencies, the most commonly used baud rates can be generated
by using the UBRR settings in Table 15. UBRR values that yield an actual baud rate dif-
fering less than 2% from the target baud rate, are boldfaced in the table. However, using
baud rates that have more than 1% error is not recommended. High error ratings give
less noise resistance.
Table 15. UBRR Settings at Various Crystal Frequencies
Baud Rate
1 MHz %Error 1.8432 MHz %Error
2 MHz %Error 2.4576 MHz %Error
2400 UBRR= 25 0.2 UBRR= 47 0.0 UBRR= 51 0.2 UBRR= 63 0.0
4800 UBRR= 12 0.2 UBRR= 23 0.0 UBRR= 25 0.2 UBRR= 31 0.0
9600 UBRR= 6 7.5 UBRR= 11 0.0 UBRR= 12 0.2 UBRR= 15 0.0
14400 UBRR= 3 7.8 UBRR= 7 0.0 UBRR= 8 3.7 UBRR= 10 3.1
19200 UBRR= 2 7.8 UBRR= 5 0.0 UBRR= 6 7.5 UBRR= 7 0.0
28800 UBRR= 1 7.8 UBRR= 3 0.0 UBRR= 3 7.8 UBRR= 4 6.3
38400 UBRR= 1 22.9 UBRR= 2 0.0 UBRR= 2 7.8 UBRR= 3 0.0
57600 UBRR= 0 7.8 UBRR= 1 0.0 UBRR= 1 7.8 UBRR= 2 12.5
76800 UBRR= 0 22.9 UBRR= 1 33.3 UBRR= 1 22.9 UBRR= 1 0.0
115200 UBRR= 0 84.3 UBRR= 0 0.0 UBRR= 0 7.8 UBRR= 0 25.0
Baud Rate 3.2768 MHz %Error 3.6864 MHz %Error
4 MHz %Error 4.608 MHz %Error
2400 UBRR= 84 0.4 UBRR= 95 0.0 UBRR= 103 0.2 UBRR= 119 0.0
4800 UBRR= 42 0.8 UBRR= 47 0.0 UBRR= 51 0.2 UBRR= 59 0.0
9600 UBRR= 20 1.6 UBRR= 23 0.0 UBRR= 25 0.2 UBRR= 29 0.0
14400 UBRR= 13 1.6 UBRR= 15 0.0 UBRR= 16 2.1 UBRR= 19 0.0
19200 UBRR= 10 3.1 UBRR= 11 0.0 UBRR= 12 0.2 UBRR= 14 0.0
28800 UBRR= 6 1.6 UBRR= 7 0.0 UBRR= 8 3.7 UBRR= 9 0.0
38400 UBRR= 4 6.3 UBRR= 5 0.0 UBRR= 6 7.5 UBRR= 7 6.7
57600 UBRR= 3 12.5 UBRR= 3 0.0 UBRR= 3 7.8 UBRR= 4 0.0
76800 UBRR= 2 12.5 UBRR= 2 0.0 UBRR= 2 7.8 UBRR= 3 6.7
115200 UBRR= 1 12.5 UBRR= 1 0.0 UBRR= 1 7.8 UBRR= 2 20.0
Baud Rate 7.3728 MHz %Error
8 MHz %Error 9.216 MHz %Error 11.059 MHz %Error
2400 UBRR= 191 0.0 UBRR= 207 0.2 UBRR= 239 0.0 UBRR= 287 -
4800 UBRR= 95 0.0 UBRR= 103 0.2 UBRR= 119 0.0 UBRR= 143 0.0
9600 UBRR= 47 0.0 UBRR= 51 0.2 UBRR= 59 0.0 UBRR= 71 0.0
14400 UBRR= 31 0.0 UBRR= 34 0.8 UBRR= 39 0.0 UBRR= 47 0.0
19200 UBRR= 23 0.0 UBRR= 25 0.2 UBRR= 29 0.0 UBRR= 35 0.0
28800 UBRR= 15 0.0 UBRR= 16 2.1 UBRR= 19 0.0 UBRR= 23 0.0
38400 UBRR= 11 0.0 UBRR= 12 0.2 UBRR= 14 0.0 UBRR= 17 0.0
57600 UBRR= 7 0.0 UBRR= 8 3.7 UBRR= 9 0.0 UBRR= 11 0.0
76800 UBRR= 5 0.0 UBRR= 6 7.5 UBRR= 7 6.7 UBRR= 8 0.0
115200 UBRR= 3 0.0 UBRR= 3 7.8 UBRR= 4 0.0 UBRR= 5 0.0
47
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