Rev. 1.0, 03/01, page 162 of 280
13.3.8
Bit Rate Register (BRR)
BRR is an 8-bit register that adjusts the bit rate. The initial value of BRR is H'FF. Table 13-2
shows the relationship between the N setting in BRR and the N setting in bits CKS1 and CKS0 of
SMR in asynchronous mode. Table 13-3 shows the maximum bit rate for each frequency in
asynchronous mode. The value shown in both tables 13-2 and 13-3 are values in active (high-
speed) mode. Table 13-4 shows the relationship between the N setting in BRR and the N setting in
bits CKS1 and CKS0 of SMR in clocked synchronous mode. The values shown in table 13-4 are
values in active (high-speed) mode. The N setting in BRR and error for other operating
frequencies and bit rates can be obtained by the following formulas:
[Asynchronous mode]
N =
φ
×
(10
6
– 1)
64
×
2
2n–1
×
B
Error(%) = - 1
×
100
φ
×
10
6
B
×
64
×
2
2n–1
×
(N + 1)
[Clocked synchronous mode]
N =
φ
×
(10
6
– 1)
8
×
2
2n–1
×
B
B: Bit rate (bit/s)
N: BRR setting for baud rate generator (0
≤
N
≤
255)
φ
: Operating frequency (MHz)
n: SMR
Summary of Contents for H8/3670F-ZTAT HD64F3670
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