Section 15
Serial Communication Interface (SCI)
Rev. 1.00 Apr. 28, 2008 Page 419 of 994
REJ09B0452-0100
15.3.9
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 15.3 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. The
CPU can always read BRR. The CPU can write to BRR only at the initial settings; do not have the
CPU write to BRR in transmission, reception, and simultaneous data transmission and reception.
Table 15.3 Relationships between N Setting in BRR and Bit Rate B
Mode Bit
Rate
Error
Asynchronous mode
B =
64 × 2 × (N + 1)
2n – 1
φ
× 10
6
Error (%) = { – 1 } × 100
B × 64 × 2 × (N + 1)
2n – 1
φ
× 10
6
Clocked synchronous mode
B =
8 × 2 × (N + 1)
2n – 1
φ
× 10
6
Smart card interface mode
B =
S × 2 × (N + 1)
2n + 1
φ
× 10
6
Error (%)
=
B × S × 2 × (N + 1)
–1 × 100
2n + 1
φ
× 10
6
{ }
[Legend]
B:
Bit rate (bit/s)
N:
BRR setting for baud rate generator (0
≤
N
≤
255)
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 15.4 shows sample N settings in BRR in normal asynchronous mode. Table 15.5 shows the
maximum bit rate settable for each frequency. Table 15.7 and 15.9 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 15.7.4, Receive Data Sampling Timing and Reception Margin. Tables 15.6
and 15.8 show the maximum bit rates with external clock input.
Содержание H8S/2100 Series
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Страница 92: ...Section 2 CPU Rev 1 00 Apr 28 2008 Page 66 of 994 REJ09B0452 0100...
Страница 158: ...Section 5 Interrupt Controller Rev 1 00 Apr 28 2008 Page 132 of 994 REJ09B0452 0100...
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Страница 380: ...Section 12 16 Bit Duty Period Measurement Timer TDP Rev 1 00 Apr 28 2008 Page 354 of 994 REJ09B0452 0100...
Страница 416: ...Section 13 8 Bit Timer TMR Rev 1 00 Apr 28 2008 Page 390 of 994 REJ09B0452 0100...
Страница 494: ...Section 15 Serial Communication Interface SCI Rev 1 00 Apr 28 2008 Page 468 of 994 REJ09B0452 0100...
Страница 612: ...Section 18 I 2 C Bus Interface IIC Rev 1 00 Apr 28 2008 Page 586 of 994 REJ09B0452 0100...
Страница 706: ...Section 20 LPC Interface LPC Rev 1 00 Apr 28 2008 Page 680 of 994 REJ09B0452 0100...
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Страница 1008: ...Section 28 Electrical Characteristics Rev 1 00 Apr 28 2008 Page 982 of 994 REJ09B0452 0100...
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