Fujitsu 8FX User Manual

MB95630H Series
MN702-00009-2v0-E FUJITSU SEMICONDUCTOR LIMITED 21
CHAPTER 3 CLOCK CONTROLLER
3.1 Overview
■ Standby Mode
The clock controller selects whether to enable or disable clock oscillation and clock supply to
the internal circuitry according to the standby mode selected. With the exception of time-base
timer mode and watch mode, the standby mode can be set independently of the clock mode.
Table 3.1-2 shows the relationships between standby modes and clock supply states.
In every standby mode, two further operating mode options, normal standby mode and deep
standby mode, can be selected by the deep standby mode control bit in the standby control
register 2 (STBC2:DSTBYX).
For details, see "3.5.1 Notes on Using Standby Mode".
Note:
Clocks that are not mentioned in Table 3.1-2 are supplied under particular settings.
For example, with main clock mode being used in stop mode, when SYCC2:SOSCE or
SYCC2:SCRE has been set to "1", the watch prescaler continues its operation.
In addition, with the hardware watchdog timer already started, the watchdog timer
operates also in standby mode, depending on the settings of the non-volatile register
(NVR) interface. For details of the non-volatile register (NVR) interface, see "CHAPTER
27 NON-VOLATILE REGISTER (NVR) INTERFACE".
Table 3.1-2 Standby Mode and Clock Supply States
Standby mode Clock supply state
Sleep mode
Clock supply to the CPU is stopped. As a result, the CPU stops operating, but other
peripheral functions continue operating.
Time-base timer mode
Clock signals are only supplied to the time-base timer and the watch prescaler, while the
clock supply to other circuits is stopped. As a result, all the functions other than the time-
base timer, watch prescaler, external interrupt, and low-voltage detection reset (option)
are stopped.
The time-base timer mode can be used in main clock mode, main CR clock mode and
main CR PLL clock mode.
Watch mode
Main clock oscillation is stopped. Clock signals are supplied only to the watch prescaler,
while clock supply to other circuits is stopped. As a result, all the functions other than
the watch prescaler, external interrupt, and low-voltage detection reset (option) are
stopped.
The watch mode is the standby mode that can be used in subclock mode and sub-CR
clock mode.
Stop mode
Main clock oscillation and subclock oscillation are stopped, and clock supply to all
circuits is stopped. As a result, all the functions other than external interrupt and low-
voltage detection reset (option) are stopped.

Fujitsu 8FX Specifications

General

Brand	Fujitsu
Model	8FX
Category	Computer Hardware
Language	English