UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 662

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(1) Release by non-maskable interrupt
(2) Release by maskable interrupt request
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When a non-maskable interrupt is generated, the PD784026 is released from HALT mode irrespective of whether
the interrupt acknowledgment enabled state (EI) or disabled state (DI) is in effect.
When the PD784026 is released from HALT mode, if the non-maskable interrupt that released HALT mode can be
acknowledged, acknowledgment of that non-maskable interrupt is performed and a branch is made to the service
program. If the interrupt cannot be acknowledged, the instruction following the instruction that set the HALT mode (the
MOV STBC, #byte instruction) is executed, and the non-maskable interrupt that released the HALT mode is
acknowledged when acknowledgment becomes possible. See 20.6 NON-MASKABLE INTERRUPT ACKNOWLEDG-
MENT OPERATION for details of non-maskable interrupt acknowledgment.
HALT mode release by a maskable interrupt request can only be performed by an interrupt for which the interrupt mask
flag is 0.
When HALT mode is released, if an interrupt can be acknowledged when the interrupt request enable flag (IE) is set
(1), a branch is made to the interrupt service program. If the interrupt cannot be acknowledged and if the IE flag is
cleared (0), execution is resumed from the instruction following the instruction that set the HALT mode. See 20.7
MASKABLE INTERRUPT ACKNOWLEDGMENT OPERATION for details of interrupt acknowledgment.
With macro service, HALT mode is released temporarily, service is performed once, then HALT mode is restored. When
macro service has been performed the specified number of times, HALT mode is released if the VCIE bit in the macro
service mode register of the macro service control word is cleared (0). The operation after release in this case is the
same as for release by a maskable interrupt described earlier. If the VCIE bit is set (1), the HALT mode is entered
again and is released by the next interrupt request.
Caution The HALT mode cannot be released by the watchdog timer.
CHAPTER 22 STANDBY FUNCTION