Fujitsu F2MC-8L Series Hardware Manual page 96

Table 3.6-2 Operating States in Each Clock Mode (Continued)
Main clock
Clock speed SYCC
mode register (CS1,
CS0)
Sub-
clock —
mode
FCH:
FCL:
*:
Reference:
In each clock mode, the CPU can enter the corresponding standby mode. For the standby
mode, see Section 3.7 "Standby Modes."
Clock Gear Function (Main clock Speed Select Function)
One of the four different main clock speeds can be selected by setting the main clock speed
select bits (CS1 and CS0) in the system clock control register (SYCC) to the corresponding
value between "00
The CPU and peripheral circuits operate at the selected main clock speed. Note, however, that
the clock gear function has no effect on the timebase timer and watch prescaler.
Lowering the main clock speed reduces power consumption.
Operation in Main Clock Mode
During normal operation in main clock mode (main-RUN mode), both of the main clock and
subclock oscillate. While the watch prescaler operates with the subclock, the CPU, timebase
timer, and other peripheral circuits operate with the main clock.
During operation in main clock mode, the main clock speed for other than the timebase timer
can be switched (by using the clock gear function).
specified, the CPU can enter main-sleep or main-stop mode.
Even when any type of reset occurs, the CPU always restarts operation in main-RUN mode
(waking up from each operation mode by a reset).
Clock generation
Standby
Main Sub-
mode
clock clock
RUN
Oscil-
lating
Sleep
Off
Stop
Watch Oscil-
Off
mode lating
main clock oscillation
Subclock oscillation
Since the timebase timer operates with the main clock, it stops operation in
subclock mode.
" and "11 ".
B B
Operating clock for each module
Time-
CPU base
timer
F
CL
Off*
Off
Off
Off Off*
Pe- Watch
ripher- pre-
als scaler
F F
CL CL
Off Off
Off F
CL
In addition, when standby mode is
3.6 Clocks
Standby
mode
wake-up
source
(other
than
reset)
Interrupt
requests
External
interrupt
External/
watch
interrupt
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