UPD780828A Datasheet, PDF (376/472 Pages) NEC – 8-bit Single-Chip Microcontroller

Chapter 21 Standby Function
(2) HALT mode clear
The HALT mode can be cleared with the following four types of sources.
(a) Clear upon unmasked interrupt request
An unmasked interrupt request is used to clear the HALT mode. If interrupt acknowledge is ena-
bled, vectored interrupt service is carried out. If disabled, the next address instruction is executed.
Figure 21-3: HALT Mode Clear upon Interrupt Generation
Standby
Release Signal
HALT
Instruction
Operating
Mode
HALT Mode
Wait
Wait
Clock
Oscillation
Operating Mode
Remarks: 1. The broken line indicates the case when the interrupt request which has cleared the
standby status is acknowledged.
2. Wait time will be as follows:
• When vectored interrupt service is carried out : 8 to 9 clocks
• When vectored interrupt service is not carried out : 2to 3 clocks
(b) Clear upon non-maskable interrupt request
The HALT mode is cleared and vectored interrupt service is carried out whether interrupt acknowl-
edge is enabled or disabled.
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User’s Manual U16504EE1V1UD00