The method of calculating the value to be set in the bit rate register (BRR) from the operating
frequency and bit rate, on the other hand, is shown below. N is an integer, 0 ≤ N ≤ 255, and the
smaller error is specified.
ø
N =
S × 2
× B
2n+1
Table 17-6 Examples of BRR Settings for Bit Rate B (bit/s) (When n = 0 and S = 372)
7.1424
10.00
bit/s N Error
N
Error
9600 0 0.00
1
30
Table 17-7 Maximum Bit Rate at Various Frequencies (Smart Card Interface Mode)
(when S = 372)
ø (MHz)
7.1424
10.00
10.7136
13.00
14.2848
16.00
18.00
20.00
25.00
28.00
The bit rate error is given by the following formula:
Error (%) = (
S × 2
786
× 10
6
– 1
10.7136
13.00
14.2848
N Error
N Error
N Error
1 25
1 8.99
1 0.00
Maximum Bit Rate (bit/s)
9600
13441
14400
17473
19200
21505
24194
26882
33602
37634
ø
× B × (N + 1)
2n+1
ø (MHz)
16.00
18.00
N Error
N Error
1 12.01
2 15.99
N
0
0
0
0
0
0
0
0
0
0
× 10
– 1) × 100
6
20.00
25.00
28.00
N Error
N Error
N Error
2
6.60
3 12.49
3 1.99
n
0
0
0
0
0
0
0
0
0
0