Rev. 1.0, 02/00, page 417 of 1141
The BRR1 setting is found from the following equations.
•
Asynchronous mode:
N =
φ
×
10
6
−
1
64
×
2
2n
−
1
×
B
•
Synchronous mode:
N =
φ
×
10
6
−
1
8
×
2
2n
−
1
×
B
Where
B:
Bit rate (bits/s)
N:
BRR1 setting for baud rate generator (0
≤
N
≤
255)
φ
:
Operating frequency (MHz)
n:
Baud rate generator input clock (n = 0 to 3)
(See the table below for the relation between n and the clock.)
SMR1 Setting
n
Clock
CKS1
CKS0
0
φ
0
0
1
φ
/4
0
1
2
φ
/16
1
0
3
φ
/64
1
1
The bit rate error in asynchronous mode is found from the following equation:
Error (% ) = {
φ
×
10
6
−
1
}
×
100
(N + 1)
×
B
×
64
×
2
2n
−
1
Table 22.5 shows the maximum bit rate for each frequency in asynchronous mode. Tables 22.6
and 22.7 show the maximum bit rates with external clock input.