Renesas H8SX/1650 Hardware Manual page 578

Section 17 Clock Pulse Generator
Bit Bit Name
2 BCK2
1 BCK1
0 BCK0
[Legend]
X: Don't care
Rev.2.00 Jun. 28, 2007 Page 556 of 666
REJ09B0311-0200
Initial
Value R/W Description
0 R/W External Bus Clock (Bφ) Select
1 R/W These bits select the frequency of the external bus clock.
The ratio to the input clock is as follows:
0 R/W
000: × 4
001: × 2
010: × 1
011: × 1/2
1XX: Setting prohibited
The frequency of the external bus clock should be lower
than that of the system clock. Though these bits can be
set so as to make the frequency of the external bus clock
higher than that of the system clock, the clocks will have
the same frequency in reality.