CHAPTER 8 CLOCK GENERATION FUNCTION
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User’s Manual U15195EJ5V0UD
8.5.3 HALT mode
(1) Setting and operation status
In the HALT mode, the clock generator (oscillator and PLL synthesizer) continues to operate, but the
operation clock of the CPU is stopped. Since the supply of clocks to on-chip peripheral I/O units other than
the CPU continues, operation continues. The power consumption of the overall system can be reduced by
setting the system to HALT mode while the CPU is idle.
The system is switched to HALT mode by the HALT instruction.
Although program execution stops in the HALT mode, the contents of all registers, internal RAM, and ports
are maintained in the state they were in immediately before HALT mode began. Also, operation continues for
all on-chip peripheral I/O units (other than ports) that do not depend on CPU instruction processing. Table 8-2
shows the status of each hardware unit in the HALT mode.
Table 8-2. Operation Status in HALT Mode
Function Operation
Status
Clock generator
Operating
Internal system clock
Operating
CPU Stopped
Ports Maintained
On-chip peripheral I/O (excluding ports)
Operating
Internal data
All internal data such as CPU registers, statuses, data,
and the contents of internal RAM are maintained in the
state they were in immediately before HALT mode
began.
AD0 to AD15
A16 to A21
RD, ASTB
UWR, LWR
WAIT
Operating
CLKOUT Clock
output
Содержание PD703114
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