Clock - Hitachi H8/3022 Hardware Manual

12.3.5

Clock

Only an internal clock generated by the on-chip 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 and
CKS0 bits in SMR. The formula for calculating the bit rate is as shown below. Table 12-5 shows
some sample bit rates.
If clock output is selected by setting CKE0 to 1, a clock with a frequency of 372 times the bit rate
is output from the SCK
B =
1488 × 2
2n–1
Where: N = Value set in BRR (0 ≤ N ≤ 255)
B = Bit rate (bit/s)
ø = Operating frequency* (MHz)
n = See table 12-4
Table 12-4 Correspondence between n and CKS1, CKS0
n CKS1
0 0
1
2 1
3
Note: If the gear function is used to divide the system clock frequency,use the divided frequency to
calculate the bit rate. The equation above applies directly to 1/1 frequency division.
Table 12-5 Examples of Bit Rate B (bit/s) for Various BRR Settings (When n = 0)
N 7.1424
0 9600.0
1 4800.0
2 3200.0
Note: Bit rates are rounded off to one decimal place.
396
pin.
0
ø
× 10
× (N + 1)
CKS0
0
1
0
1
10.00 10.7136
13440.9 14400.0
6720.4 7200.0
4480.3 4800.0
6
ø (MHz)
13.00 14.2848
17473.1 19200.0
8736.6 9600.0
5824.4 6400.0
16.00 18.00
21505.4 24193.5
10752.7 12096.8
7168.5 8064.5