Prescalers - Renesas H8 Series Hardware Manual

Figure 4.8 shows the equivalent circuit of the 32.768-kHz crystal resonator.
X
1
Figure 4.8 Equivalent Circuit of 32.768-kHz Crystal Resonator
Pin Connection when Not Using Subclock: When the subclock is not used, connect pin X
V and leave pin X
CC 2
Figure 4.9 Pin Connection when not Using Subclock
4.4

Prescalers

The H8/3644 Group is equipped with two on-chip prescalers having different input clocks
(prescaler S and prescaler W). Prescaler S is a 13-bit counter using the system clock (φ) as its
input clock. Its prescaled outputs provide internal clock signals for on-chip peripheral modules.
Prescaler W is a 5-bit counter using a 32.768-kHz signal divided by 4 (φ
prescaled outputs are used by timer A as a time base for timekeeping.
Prescaler S (PSS): Prescaler S is a 13-bit counter using the system clock (φ) as its input clock. It
is incremented once per clock period.
Prescaler S is initialized to H'0000 by a reset, and starts counting on exit from the reset state.
C
S
L
S
open, as shown in figure 4.9.
X
1
X
2
Section 4 Clock Pulse Generators
R
S
C
C = 1.5 pF (typ.)
0
0
Ω
R = 14 k (typ.)
S
f = 32.768 kHz
W
Crystal resonator:
V
CC
Open
Rev. 6.00 Sep 12, 2006 page 85 of 526
X
2
MX38T
(Nihon Denpa Kogyo)
1
/4) as its input clock. Its
W
REJ09B0326-0600
to