80C186EB/80C188EB, 80L186EB/80L188EB
272433 – 3
(A) Crystal Connection
NOTE:
The L
1
C
1
network is
only
required when using a third-
overtone crystal.
272433 – 4
(B) Clock Connection
Figure 2. Clock Configurations
The following parameters are recommended when
choosing a crystal:
Temperature Range:
Application Specific
ESR (Equivalent Series Resistance):
40
X
max
C0 (Shunt Capacitance of Crystal):
7.0 pF max
C
L
(Load Capacitance):
20 pF
g
2 pF
Drive Level:
1 mW max
80C186EB PERIPHERAL
ARCHITECTURE
The 80C186EB has integrated several common sys-
tem peripherals with a CPU core to create a com-
pact, yet powerful system. The integrated peripher-
als are designed to be flexible and provide logical
interconnections between supporting units (e.g., the
interrupt control unit supports interrupt requests
from the timer/counters or serial channels).
The list of integrated peripherals includes:
#
7-Input Interrupt Control Unit
#
3-Channel Timer/Counter Unit
#
2-Channel Serial Communications Unit
#
10-Output Chip-Select Unit
#
I/O Port Unit
#
Refresh Control Unit
#
Power Management Unit
The registers associated with each integrated peri-
heral are contained within a 128 x 16 register file
called the Peripheral Control Block (PCB). The PCB
can be located in either memory or I/O space on
any 256 Byte address boundary.
Figure 3 provides a list of the registers associated
with the PCB. The Register Bit Summary at the end
of this specification individually lists all of the regis-
ters and identifies each of their programming attri-
butes.
Interrupt Control Unit
The 80C186EB can receive interrupts from a num-
ber of sources, both internal and external. The inter-
rupt control unit serves to merge these requests on
a priority basis, for individual service by the CPU.
Each interrupt source can be independently masked
by the Interrupt Control Unit (ICU) or all interrupts
can be globally masked by the CPU.
Internal interrupt sources include the Timers and Se-
rial channel 0. External interrupt sources come from
the five input pins INT4:0. The NMI interrupt pin is
not controlled by the ICU and is passed directly to
the CPU. Although the Timer and Serial channel
each have only one request input to the ICU, sepa-
rate vector types are generated to service individual
interrupts within the Timer and Serial channel units.
Timer/Counter Unit
The 80C186EB Timer/Counter Unit (TCU) provides
three 16-bit programmable timers. Two of these are
highly flexible and are connected to external pins for
control or clocking. A third timer is not connected to
any external pins and can only be clocked internally.
However, it can be used to clock the other two timer
channels. The TCU can be used to count external
events, time external events, generate non-repeti-
tive waveforms, generate timed interrupts. etc.
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