HD64F2149 Datasheet, PDF (464/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

The BRR setting is found from the following equations.
Asynchronous mode:
N
=
64
×
φ
2^2n–1
×
B
×
10⁶
–
1
Synchronous mode:
N=
φ
8 × 2^2n–1 × B
× 10⁶ – 1
Where B: Bit rate (bits/s)
N: BRR setting for baud rate generator (0 ≤ N ≤ 255)
ø: 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.)
SMR Setting
n
Clock
CKS1
CKS0
0
ø
0
0
1
ø/4
0
1
2
ø/16
1
0
3
ø/64
1
1
The bit rate error in asynchronous mode is found from the following equation:
Error
(%)

= _{(N}
+
1)
φ × 10⁶
× B × 64
×
2^2n–1
–
1
× 100
430