Bit Rate Register (Brr) - Renesas H8S Series Hardware Manual

Bit 0—Multiprocessor Bit Transfer (MPBT): When transmission is performed using multiprocessor format in
asynchronous mode, MPBT stores the multiprocessor bit to be added to the transmit data.
The MPBT bit setting is invalid when multiprocessor format is not used, when not transmitting, and in clocked
synchronous mode.
Bit 0
MPBT
0
1
14.2.8

Bit Rate Register (BRR)

Bit : 7
Initial value : 1
R/W : R/W
BRR is an 8-bit register that sets the serial transfer bit rate in accordance with the baud rate generator operating clock
selected by bits CKS1 and CKS0 in SMR.
BRR can be read or written to by the CPU at all times.
BRR is initialized to H'FF by a reset, and by putting the device in standby mode or module stop mode. In the H8S/2398,
H8S/2394, H8S/2392, and H8S/2390, however, the value in BRR is initialized to H'FF by a reset, or in hardware standby
mode, but BRR retains its current state when the device enters software standby mode or module stop mode.
As baud rate generator control is performed independently for each channel, different values can be set for each channel.
Table 14-3 shows sample BRR settings in asynchronous mode, and table 14-4 shows sample BRR settings in clocked
synchronous mode.
Table 14-3 BRR Settings for Various Bit Rates (Asynchronous Mode)
Bit Rate
(bit/s)
110
150
300
600
1200
2400
4800
9600
19200
31250
38400
Rev.6.00 Oct.28.2004 page 478 of 1016
REJ09B0138-0600H
Description
Data with a 0 multiprocessor bit is transmitted
Data with a 1 multiprocessor bit is transmitted
6 5
1 1
R/W R/W
ø = 2 MHz
Error
n N (%) n
1 141 0.03 1
1 103 0.16 1
0 207 0.16 0
0 103 0.16 0
0 51 0.16 0
0 25 0.16 0
0 12 0.16 0
0 6 — 0
0 2 — 0
0 1 0.00 0
0 1 — 0
4 3 2
1 1 1
R/W R/W R/W
ø = 2.097152 MHz ø = 2.4576 MHz
Error
N (%) n
148 –0.04 1
108 0.21 1
217 0.21 0
108 0.21 0
54 –0.70 0
26 1.14 0
13 –2.48 0
6 –2.48 0
2 — 0
1 — 0
1 — 0
(Initial value)
1 0
1 1
R/W R/W
ø = 3 MHz
Error
N (%) n N
174 –0.26 1 212
127 0.00 1 155
255 0.00 1 77
127 0.00 0 155
63 0.00 0 77
31 0.00 0 38
15 0.00 0 19
7 0.00 0 9
3 0.00 0 4
1 — 0 2
1 0.00 — —
Error
(%)
0.03
0.16
0.16
0.16
0.16
0.16
–2.34
–2.34
–2.34
0.00
—