Z380 Datasheet, PDF (100/115 Pages) Zilog, Inc. – MICROPROCESSOR

ZILOG
MICROPROCESSOR
Standby Mode Exit With External Interrupts
Standby mode can be exited by asserting input /NMI.
Asserting the maskable interrupt inputs /INT3-/INT0 may
also exit standby mode, if the global interrupt flag IEF1 was
previously enabled at logic 1, and for those requests
individually enabled, as indicated in the Interrupt Enable
Register.
When exit conditions are met, /STNBY goes to logic 1,
allowing the external crystal oscillator that drives the Z380
MPU’s CLK input to restart.
BUSCLK
The Z380 MPU’s internal warm-up counter proceeds to
count, for a duration long enough for the oscillator to
stabilize, as selected by the WM bits in the Standby Mode
Control Register. When the counter reaches its end-count,
clocking resumes within the Z380 MPU, as well as at the
BUSCLK and IOCLK outputs. The Z380 MPU performs an
interrupt acknowledge procedure appropriate to the inter-
rupt request that initiated the standby mode exit.
Appropriate
Acknowledge
IOCLK
/STNBY
/NMI
/INT3,2,1,0
ADDRESS
FFFFFFFFH
Figure 55. Standby Mode Exit with External Interrupts Timing
PS010001-0301