H8S2339 Datasheet, PDF (712/1244 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series

Section 15 Smart Card Interface
15.3.5 Clock
Only an internal clock generated by the built-in baud rate generator can be used as the
transmit/receive clock for the smart card interface. The bit rate is set with BRR and the CKS1,
CKS0, BCP1, and BCP0 bits in SMR. The formula for calculating the bit rate is as shown below.
Table 15.5 shows some sample bit rates.
If clock output is selected by setting CKE0 to 1, the clock is output from the SCK pin. The clock
frequency is determined by the bit rate and the setting of bits BCP1 and BCP0.
B=
φ
S × 2²ⁿ⁺¹ × (N + 1)
× 10⁶
Where: N = Value set in BRR (0 ≤ N ≤ 255)
B = Bit rate (bits/s)
φ = Operating frequency (MHz)
n = See table 15.4
S = Number of internal clock cycles in 1-bit period set by bits BCP1 and BCP0
Table 15.4 Correspondence between n and CKS1, CKS0
n
CKS1
CKS0
0
0
0
1
1
2
1
0
3
1
Table 15.5 Examples of Bit Rate B (bits/s) for Various BRR Settings
(When n = 0 and S = 372)
φ (MHz)
N
10.00 10.714 13.00 14.285 16.00
0
13441 14400 17473 19200 21505
1
6720 7200
8737
9600 10753
2
4480 4800
5824
6400 7168
Note: Bit rates are rounded to the nearest whole number.
18.00
24194
12097
8065
20.00
26882
13441
8961
25.00
33602
16801
11201
Rev.4.00 Sep. 07, 2007 Page 682 of 1210
REJ09B0245-0400