Z86D990 Datasheet, PDF (24/102 Pages) Zilog, Inc. – Low-Voltage Micro controllers with ADC

Z86D990/Z86D991 OTP and Z86L99X ROM
Low-Voltage Microcontrollers with ADC
17
Figure 9. External Interrupt Sources IRQ₀–IRQ₂ Block Diagram
The programming bits for the Interrupt Edge Select function are located in the IRQ
register, bits 6 and 7. The configuration of these bits and the resulting interrupt
edge is shown in Table 4.
Table 4. Interrupt Edge Select for External Interrupts
Interrupt Request Register
Bit 7
Bit 6
0
0
0
1
1
0
1
1
Interrupt Edge
IRQ₂ (P51)
Falling
IRQ₀ (P52)
Falling
Falling
Rising
Rising
Falling
Rising/Falling Rising/Falling
Note:
Although interrupts are edge triggered, minimum interrupt
request Low and High times must be observed for proper
operation. See “Electrical Characteristics” on page 85 for exact
timing requirements (T_WIL, T_WIH) on external interrupt
requests.
Internal Interrupt Sources
Internal sources are ORed with the external sources, so that either an internal or
external source can trigger the interrupt.
Interrupt Request Register Logic and Timing
Figure 10 shows the logic diagram for the Interrupt Request Register. The leading
edge of an interrupt request sets the first flip-flop. It remains set until the interrupt
requests are sampled.
PS003807-1002
PRELIMINARY