CHAPTER 8 CLOCK GENERATION FUNCTION
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User’s Manual U14492EJ3V0UD
8.5.3 HALT mode
(1) Setting and operation status
In 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 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 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 A23
RD, ASTB
UWR, LWR
CS0 to CS7
HLDRQ
HLDAK
WAIT
Operating
CLKOUT
Clock output
Содержание V850E/IA1 mPD703116
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