NEC uPD78056Y User Manual

Page 528

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528

CHAPTER 23 STANDBY FUNCTION

HALT
Instruction

Interrupt
Request

Wait

Standby
Release Signal

Operating
Mode

Clock

HALT Mode

Wait

Oscillation

Operating Mode

(2) HALT mode clear

The HALT mode can be cleared with the following four types of sources.

(a) Clear upon unmasked interrupt request

When an unmasked interrupt request is generated, the HALT mode is cleared. If interrupt request

acknowledge is enabled, vectored interrupt service is carried out. If disabled, the next address instruction

is executed.

Figure 23-2. HALT Mode Clear upon Interrupt Request Generation

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:

2 to 3 clocks

(b) Clear upon non-maskable interrupt request

When a non-maskable interrupt request is generated, the HALT mode is cleared and vectored interrupt

service is carried out whether interrupt acknowledge is enabled or disabled.

(c) Clear upon unmasked test input

When an unmasked test signal is input, the HALT mode is cleared and the next address instruction of

the HALT instruction is executed.

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