Section 13 Serial Communication Interface (SCI)
Rev.2.00 Jun. 28, 2007 Page 471 of 666
REJ09B0311-0200
13.3.9
Bit Rate Register (BRR)
BRR is an 8-bit register that adjusts the bit rate. As the SCI performs baud rate generator control
independently for each channel, different bit rates can be set for each channel. Table 13.2 shows
the relationships between the N setting in BRR and bit rate B for normal asynchronous mode and
clocked synchronous mode, and smart card interface mode. The initial value of BRR is H'FF, and
it can be read from or written to by the CPU at all times.
Table 13.2 Relationships between N Setting in BRR and Bit Rate B
Mode Bit
Rate
Error
Asynchronous mode
N =
−
1
64 × 2 × B
2n – 1
P
φ
× 10
6
Error (%) = { – 1 } × 100
B × 64 × 2 × (N + 1)
2n – 1
P
φ
× 10
6
Clocked synchronous mode
N =
−
1
8 × 2 × B
2n – 1
P
φ
× 10
6
Smart card interface mode
N =
−
1
S × 2 × B
P
φ
× 10
6
2n + 1
Error (%)
=
B × S × 2 × (N + 1)
– 1 × 100
2n + 1
P
φ
× 10
6
{ }
[Legend]
B:
Bit rate (bit/s)
N:
BRR setting for baud rate generator (0
≤
N
≤
255)
P
φ
:
Operating frequency (MHz)
n and S: Determined by the SMR settings shown in the following table.
SMR Setting
SMR Setting
CKS1 CKS0 n BCP1 BCP0 S
0 0 0
0 0 32
0 1 1
0 1 64
1 0 2
1 0 372
1 1 3
1 1 256
Table 13.3 shows sample N settings in BRR in normal asynchronous mode. Table 13.4 shows the
maximum bit rate settable for each operating frequency. Tables 13.6 and 13.8 show sample N
settings in BRR in clocked synchronous mode and smart card interface mode, respectively. In
smart card interface mode, the number of basic clock cycles S in a 1-bit data transfer time can be
selected. For details, see section 13.7.4, Receive Data Sampling Timing and Reception Margin.
Tables 13.5 and 13.7 show the maximum bit rates with external clock input.
Содержание H8SX/1650
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Страница 142: ...Section 5 Interrupt Controller Rev 2 00 Jun 28 2007 Page 120 of 666 REJ09B0311 0200...
Страница 326: ...Section 8 I O Ports Rev 2 00 Jun 28 2007 Page 304 of 666 REJ09B0311 0200...
Страница 470: ...Section 12 Watchdog Timer WDT Rev 2 00 Jun 28 2007 Page 448 of 666 REJ09B0311 0200...
Страница 546: ...Section 13 Serial Communication Interface SCI Rev 2 00 Jun 28 2007 Page 524 of 666 REJ09B0311 0200...
Страница 566: ...Section 14 A D Converter Rev 2 00 Jun 28 2007 Page 544 of 666 REJ09B0311 0200...
Страница 574: ...Section 16 RAM Rev 2 00 Jun 28 2007 Page 552 of 666 REJ09B0311 0200...
Страница 584: ...Section 17 Clock Pulse Generator Rev 2 00 Jun 28 2007 Page 562 of 666 REJ09B0311 0200...
Страница 638: ...Section 19 List of Registers Rev 2 00 Jun 28 2007 Page 616 of 666 REJ09B0311 0200...
Страница 668: ...Section 20 Electrical Characteristics Rev 2 00 Jun 28 2007 Page 646 of 666 REJ09B0311 0200...
Страница 676: ...Appendix Rev 2 00 Jun 28 2007 Page 654 of 666 REJ09B0311 0200...
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