Standby Function Operation; Halt Mode; Operation Statuses In Halt Mode - NEC PD789488 User Manual

17.2 Standby Function Operation

17.2.1 HALT mode

(1) HALT mode
The HALT mode is set by executing the HALT instruction.
The operation statuses in the HALT mode are shown in the following table.
Item
Clock generator Oscillation enabled for both main system clock and subsystem clock, but clock supply to CPU is
stopped
Subsystem clock ×4
Operation stopped
multiplication circuit
CPU Operation stopped
Ports (output latches) Status before HALT mode setting retained
16-bit timer 20 Operable
8-bit timer 50 Operable
8-bit timer 60 Operable
8-bit timer 61 Operable
Watch timer Operable
Watchdog timer Operable
Key return circuit Operable
Serial interface 20 Operable
Serial interface 1A0 Operable
LCD controller/driver Operable
A/D converter Operation stopped
Multiplier Operation stopped
Remote controller Operable
Note 8
receiver
External interrupts Operable
Notes 1. Operation is enabled when the 24-bit counter mode is selected.
2. Operation is enabled when either the subsystem clock or the input signal from timer 60 (when timer 60
is operable) is selected as the count clock.
3. Operation is enabled only when the external input clock is selected as the count clock.
4. Operation is enabled when the main system clock is selected.
5. Operation is enabled when the subsystem clock is selected.
6. Operation is enabled only when an external clock is selected.
7. The HALT instruction can be set after display instruction execution.
µ
8. PD789489 and 78F9489 only.
9. Operation is enabled only for a maskable interrupt that is not masked.
CHAPTER 17 STANDBY FUNCTION
Table 17-1. Operation Statuses in HALT Mode
HALT Mode Operation Status During Main
System Clock Operation
Subsystem Clock Subsystem Clock
Operating
Operable
Note 7
Operable
Operable
Note 9
User's Manual U15331EJ4V1UD
HALT Mode Operation Status During Subsystem
Main System Clock
Stopped Operating
Note 4
Operable
Operation stopped
Notes 4, 7 Note 7
Operable
Note 4
Operable
Clock Operation
Main System Clock
Stopped
Note 1
Operable
Note 2
Operable
Note 3
Operable
Note 3
Operable
Note 5
Operable
Note 6
Operable
Note 6
Operable
Notes 5, 7
Operable
Note 5
Operable
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