Bit Rate Register (Brr) - Renesas H8 Series Hardware Manual

Section 10 Serial Communication Interface
10.2.8

Bit Rate Register (BRR)

Bit 7
BRR7
Initial value 1
Read/Write R/W
BRR is an 8-bit register that designates the transmit/receive bit rate in accordance with the baud
rate generator operating clock selected by bits CKS1 and CKS0 of the serial mode register (SMR).
BRR can be read or written by the CPU at any time.
BRR is initialized to H'FF upon reset, and in standby, module standby, or watch mode.
Table 10.3 shows examples of BRR settings in asynchronous mode. The values shown are for
active (high-speed) mode.
Table 10.3 Examples of BRR Settings for Various Bit Rates (Asynchronous Mode) (1)
16.4 kHz
Bit Rate
(bit/s) n N
110 — —
150 — —
200 — —
250 0 1
300 — —
600 — —
1200
2400
4800
9600
19200
31250
38400
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6 5
BRR6 BRR5
1 1
R/W R/W
19.2 kHz
Error Error
(%) n N (%)
— — — —
— 0 3 0
— 0 2 0
2.5 — — —
— 0 1 0
— 0 0 0
— — —
— — —
— — —
— — —
— — —
— — —
— — —
4 3
BRR4 BRR3
1 1
R/W R/W
φ φ φ φ
1 MHz 1.2288 MHz
Error
n N (%) n
2 17 –1.36 2
2 12 0.16 3
2 9 –2.34 3
3 1 –2.34 0
0 103 0.16 3
0 51 0.16 3
0 25 0.16 2
0 12 0.16 2
— — — 0
— — — 0
— — — 0
0 0 0 —
— — — 0
2 1
BRR2 BRR1 BRR0
1 1
R/W
R/W R/W
2 MHz
Error
N (%) n N
21 –0.83 3 8
3 0 2 25
2 0 3 4
153 –0.26 2 15
1 0 2 12
0 0 0 103 0.16
1 0 0 51
0 0 0 25
7 0 0 12
3 0 — —
1 0 — —
— — 0 1
0 0 — —
0
1
Error
(%)
–1.36
0.16
–2.34
–2.34
0.16
0.16
0.16
0.16
—
—
0
—