Z86C34 Datasheet, PDF (36/70 Pages) Zilog, Inc. – CMOS Z8 MCUs WITH ASCI UART OFFER EFFICIENT, COST-EFFECTIVE DESIGN FLEXIBILITY

Z86C34/C35/C36/C44/C45/C46
CMOS Z8® MCUs with ASCI UART
FUNCTIONAL DESCRIPTION (Continued)
An interrupt resulting from AN1 maps to IRQ2, and an in-
terrupt from AN2 maps to IRQ0. Interrupts IRQ2 and IRQ0
may be rising, falling, or both edge-triggered, and are pro-
grammable by the user. The software may poll to identify
the state of the pin. When in analog mode, the IRQ1 gener-
ates by the Stop-Mode Recovery source selected by SMR
Reg. bits D4, D3, D2, or SMR2 D1 or D0.
Programming bits for the Interrupt Edge Select are located
in the IRQ register (R250), bits D7 and D6. The configura-
tion is indicated in Table 12.
Table 12. IRQ Register
IRQ
D7
D6
0
0
0
1
1
0
1
1
Notes:
F = Falling Edge
R = Rising Edge
Interrupt Edge
P31
P32
F
F
F
R
R
F
R/F
R/F
ZiLOG
Clock. The Z8 on-chip oscillator features a high-gain, par-
allel-resonant amplifier for connection to a crystal, LC, RC,
ceramic resonator, or any suitable external clock source
(XTAL1 = INPUT, XTAL2 = OUTPUT). The crystal should
be AT-cut, 16 MHz maximum, with a series resistance (RS)
of less than or equal to 100 Ohms when counting from
1 MHz to 16 MHz.
The crystal should be connected across XTAL1 and XTAL2
using the vendor’s recommended capacitor values from
each pin directly to the device Ground pin to reduce ground-
noise injection into the oscillator. The RC oscillator option
is mask-programmable on the Z8 and is selected by the cus-
tomer at the time when the ROM code is submitted.
Notes: The RC option is available up to 8 MHz. The RC
oscillator configuration must be an external resistor
connected from XTAL1 to XTAL2, with a frequency-
setting capacitor from XTAL1 to Ground (Figure 24).
For better noise immunity, the capacitors should be tied
directly to the device Ground pin (V_SS).
36
PRELIMINARY
DS007601-Z8X0499