Z86L79 Datasheet, PDF (39/58 Pages) Zilog, Inc. – Low-Voltage Microcontroller

Zilog
Z86L79/80
Low-Voltage Microcontroller
Table 3. Interrupt Types, Sources, and Vectors
Name Source
IRQ0 /DAV0, IRQ0
IRQ1, IRQ1
IRQ2
/DAV2, IRQ2,
T_IN
Vector
Location
0, 1
2, 3
4, 5
Comments
External (P32),
Rising Falling Edge
Triggered
External (P33),
Falling Edge
Triggered
External (P31),
Rising Falling Edge
Triggered
An interrupt resulting from AN1 is mapped into IRQ2, and
an interrupt from AN2 is mapped into IRQ0. Interrupts
1 ^{IRQ2 and IRQ0 may be rising, falling, or both edge trig-}
gered, and are programmable by the user. The software
can poll to identify the state of the pin.
Programming bits for the Interrupt Edge Select are located
in the IRQ Register (R250), bits D7 and D6. The configu-
ration is shown in Table 4.
Table 4. IRQ Register
IRQ
D7
D6
Interrupt Edge
IRQ2
IRQ0
IRQ3 T16
6, 7 Internal
0
0
F
F
IRQ4 T8
8, 9 Internal
0
1
F
R
IRQ5
10,11 Software generated
When more than one interrupt is pending, priorities are re-
solved by a programmable priority encoder controlled by
the Interrupt Priority register. An interrupt machine cycle is
activated when an interrupt request is granted. This dis-
ables all subsequent interrupts, saves the Program
Counter and Status Flags, and then branches to the pro-
gram memory vector location reserved for that interrupt.
All Z86L7X interrupts are vectored through locations in the
program memory. This memory location and the next byte
contain the 16-bit address of the interrupt service routine
for that particular interrupt request. To accommodate
polled interrupt systems, interrupt inputs are masked and
the Interrupt Request register is polled to determine which
of the interrupt requests need service.
1
0
R
F
1
1
R/F
R/F
Notes:
F = Falling Edge
R = Rising Edge
In analog mode, the Stop-Mode Recovery sources select-
ed by the SMR register are connected to IRQ1 input. Any
of the Stop-Mode Recovery sources for SMR (except P31,
P32, and P33) can be used to generate IRQ1 (falling edge
triggered).
Clock. The Z86L7X on-chip oscillator has a high-gain, par-
allel-resonant amplifier for connection to a crystal, LC, ce-
ramic resonator, or any suitable external clock source
(XTAL1 = Input, XTAL2 = Output). The crystal should be
AT cut, 1 MHz to 8 MHz maximum, with a series resistance
(RS) less than or equal to 100 Ohms. The Z86L7X on-chip
oscillator may be driven with a cost-effective RC network
or other suitable external clock source.
PRELIMINARY
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