MEGA128CAN Datasheet, PDF (195/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

AT90CAN128
Examples of Baud Rate
Setting
For standard crystal, resonator and external oscillator frequencies, the most commonly
used baud rates for asynchronous operation can be generated by using the UBRRn set-
tings in Table 84 up to Table 87. 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 “Asynchronous Operational Range” on page
186). The error values are calculated using the following equation:
Error[%]
=
⎛
⎝
1
–
B_-----a_---u_---d_----RB_----aa_---t_-u-e_{--d-C---R-l-o--as---et--es---t--M----a---t-c--h- ⎠⎞}
• 100%
Table 84. Examples of UBRRn Settings for Commonly Frequencies
Baud
Rate
(bps)
fclk_io = 1.0000 MHz
U2Xn = 0
U2Xn = 1
UBRRn Error UBRRn Error
fclk_io = 1.8432 MHz
U2Xn = 0
U2Xn = 1
UBRRn Error UBRRn Error
2400
25
0.2%
51
0.2%
47
0.0%
95
0.0%
4800
12
0.2%
25
0.2%
23
0.0%
47
0.0%
9600
6
-7.0%
12
0.2%
11
0.0%
23
0.0%
14.4k
3
8.5%
8
-3.5%
7
0.0%
15
0.0%
19.2k
2
8.5%
6
-7.0%
5
0.0%
11
0.0%
28.8k
1
8.5%
3
8.5%
3
0.0%
7
0.0%
38.4k
1
-18.6%
2
8.5%
2
0.0%
5
0.0%
57.6k
0
8.5%
1
8.5%
1
0.0%
3
0.0%
76.8k
–
–
1
-18.6%
1
-25.0%
2
0.0%
115.2k
–
–
0
8.5%
0
0.0%
1
0.0%
230.4k
–
–
–
–
–
–
0
0.0%
250k
–
–
–
–
–
–
–
–
500k
–
–
–
–
–
–
–
–
1M
Max. ⁽¹⁾
–
–
62.5 kbps
–
–
125 kbps
–
–
115.2 kbps
–
–
230.4 Kbps
1.
UBRRn = 0, Error = 0.0%
fclk_io = 2.0000 MHz
U2Xn = 0
U2Xn = 1
UBRRn Error UBRRn Error
51
0.2%
103
0.2%
25
0.2%
51
0.2%
12
0.2%
25
0.2%
8
-3.5%
16
2.1%
6
-7.0%
12
0.2%
3
8.5%
8
-3.5%
2
8.5%
6
-7.0%
1
8.5%
3
8.5%
1
-18.6%
2
8.5%
0
8.5%
1
8.5%
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
125 kpbs
250 kbps
4250E–CAN–12/04
195