Datasheet

CHAPTER 11 STANDBY FUNCTION
User’s Manual U18172EJ3V0UD
189
11.2 Standby Function Operation
11.2.1 HALT mode
(1) HALT mode
The HALT mode is set by executing the HALT instruction.
The operating statuses in the HALT mode are shown below.
Caution Because an interrupt request signal is used to clear the standby mode, if there is an interrupt
source with the interrupt request flag set and the interrupt mask flag clear, the standby mode
is immediately cleared if set.
Table 11-2. Operating Statuses in HALT Mode
Low-Speed Internal Oscillator can be stopped
Note 1
.
Setting of HALT Mode
Item
Low-Speed Internal
Oscillator cannot be
stopped
Note 1
.
When Low-Speed Internal
Oscillation Continues
When Low-Speed Internal
Oscillation Stops
System clock Clock supply to CPU is stopped.
CPU Operation stops.
Port (latch) Holds status before HALT mode was set.
16-bit timer/event counter 00
Note 2
Operable
Sets count clock to fXP to fXP/2
12
Operable
8-bit timer
H1
Sets count clock to f
RL/2
7
Operable Operable Operation stops.
“System clock” selected as
operating clock
Setting disabled. Operation stops.
Watchdog
timer
“Low-speed internal oscillation
clock” selected as operating
clock
Operable
(Operation continues)
Operation stops.
A/D converter
Note 2
Operable
Power-on-clear circuit Always operates.
Low-voltage detector Operable
External interrupt Operable
Notes 1. “Cannot be stopped” or “Stopped by software” is selected for low-speed internal oscillator by the option byte
(for the option byte, see CHAPTER 15 OPTION BYTE).
2.
μ PD78F920x only
<R>