UM001600-Z8X0599
1-1
U
SER
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S
M
ANUAL
C
HAPTER
1
Z8 MCU P
RODUCT
O
VERVIEW
1.1 Z8 MCU FAMILY OVERVIEW
The ZiLOG Z8 microcontroller (MCU) product line contin-
ues to expand with new product introductions. ZiLOG MCU
products are targeted for cost-sensitive, high-volume appli-
cations including consumer, automotive, security, and
HVAC. It includes ROM-based products geared for high-
volume production (where software is stable) and one-time
programmable (OTP) equivalents for prototyping as well
as volume production where time to market or code flexi-
bility is critical (Table 1-1). A variety of packaging options
are available including plastic DIP, SOIC, PLCC, and QFP.
A generalized Z8 MCU
block diagram is shown in Figure
1-1. The same on-chip peripherals are used across the
MCU product line with the primary differences being the
amount of ROM/RAM, number of I/O lines present, and
packaging/temperature ranges available. This allows code
written for one MCU device to be easily ported to another
family member.
1.1.1 Key Product Line Features
¥
General-Purpose Register (GPR) File:
Every RAM
register acts like an accumulator, speeding instruction
execution and maximizing coding efficiency. Working
register groups allow fast context switching.
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Flexible I/O:
I/O byte, nibble, and/or bit programmable
as
inputs
or
outputs.
programmable as open-drain or push-pull on a port
basis. Inputs are Schmitt-triggered with auto latches to
hold unused inputs at a known voltage state.
Outputs
are
software
¥
Analog Inputs:
Three input pins are software
programmable as digital or analog inputs. When in the
analog mode, two comparator inputs are provided with a
common reference input. These inputs are ideal for a
variety of common functions, including threshold level
detection, analog-to-digital conversion, and short circuit
detection. Each analog input provides a unique
maskable interrupt input.
¥
Timer/Counter(T/C):
programmable 6-bit prescaler and 8-bit downcounter,
with maskable interrupt upon end-of-count. Software
controls T/C load/start/stop, countdown read (at any
time on the fly), and maskable end-of-count interrupt.
Special functions available include T
IN
(external counter
input, external gate input, or external trigger input) and
T
OUT
(external access to timer output or the internal
The
T/C
consists
of
a
system clock.) These special functions allow accurate
hardware input pulse measurement and output
waveform generation.
¥
Interrupts:
There are six vectored interrupt sources with
software-programmable enable and priority for each of
the six sources.
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Watch-Dog Timer (WDT):
An internal WDT circuit is
included as a fail-safe mechanism so that if software
strays outside the bounds of normal operation, the WDT
will timeout and reset the MCU. To maximize circuit
robustness and reliability, the default WDT clock source
is an internal RC circuit (isolated from the device clock
source).
¥
Auto Reset/Low-Voltage Protection:
All family
devices have internal Power-On Reset. ROM devices
add low-voltage protection. Low-voltage protection
ensures the MCU is in a known state at all times (in
active RUN mode or RESET) without external hardware
(or a device reset pin).
¥
Low-EMI Operation:
Mode is programmable via
software or as a mask option. This new option provides
for reduced radiated emission via clock and output drive
circuit changes.