Z86D99 ZILOG [Zilog, Inc.], Z86D99 Datasheet - Page 24

• Manufacturer Part Number: Z86D99
• Description: Low-Voltage Micro controllers with ADC
• Manufacturer: ZILOG [Zilog, Inc.]

PS003807-1002
Note:
Figure 9. External Interrupt Sources IRQ
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
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.
Interrupt Request Register
Bit 7
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
requests.
0
0
1
1
P
R
Bit 6
0
1
0
1
E
L
W
IL, T
I
Rising/Falling
IRQ
M
W
Z86D990/Z86D991 OTP and Z86L99X ROM
Falling
Falling
Rising
IH) on external interrupt
2
I
Low-Voltage Microcontrollers with ADC
(P51)
Interrupt Edge
0
–IRQ
N
A
2
Block Diagram
R
Rising/Falling
IRQ
Falling
Falling
Rising
Y
0
(P52)
17