cop87l88rd National Semiconductor Corporation, cop87l88rd Datasheet - Page 8

• Manufacturer Part Number: cop87l88rd
• Description: 8-bit Cmos Otp Microcontrollers With 16k Or 32k Memory And 8-channel A/d With Prescaler
• Manufacturer: National Semiconductor Corporation

www.national.com
Pin Descriptions
V
pins must be connected.
CKI is the clock input. This can come from an R/C generated
oscillator, or a crystal oscillator (in conjunction with CKO).
See Oscillator Description section.
RESET is the master reset input. See Reset Description sec-
tion.
The device contains three bidirectional 8-bit I/O ports (C, G
and L), where each individual bit may be independently con-
figured as an input (Schmitt Trigger inputs on ports L and G),
output or TRI-STATE under program control. Three data
memory address locations are allocated for each of these
I/O ports. Each I/O port has two associated 8-bit memory
mapped registers, the CONFIGURATION register and the
output DATA register. A memory mapped address is also re-
served for the input pins of each I/O port. (See the memory
map for the various addresses associated with the I/O ports.)
Figure 4 shows the I/O port configurations. The DATA and
CONFIGURATION registers allow for each port bit to be in-
dividually configured under software control as shown below:
PORT L is an 8-bit I/O port. All L-pins have Schmitt triggers
on the inputs.
Port L supports Multi-Input Wake Up on all eight pins. L4 and
L5 are used for the timer input functions T2A and T2B. L6
and L7 are used for the timer input functions T3A and T3B.
Port L has the following alternate features:
Port G is an 8-bit port with 5 I/O pins (G0, G2–G5), an input
pin (G6), and a dedicated output pin (G7). Pins G0 and
G2–G6 all have Schmitt Triggers on their inputs. Pin G1
serves as the dedicated WDOUT WATCHDOG output, while
pin G7 is either input or output depending on the oscillator
mask option selected. With the crystal oscillator option se-
lected, G7 serves as the dedicated output pin for the CKO
clock output. With the single-pin R/C oscillator mask option
selected, G7 serves as a general purpose input pin but is
also used to bring the device out of HALT mode with a low to
high transition on G7. There are two registers associated
with the G Port, a data register and a configuration register.
Therefore, each of the 5 I/O bits (G0, G2–G5) can be indi-
vidually configured under software control.
Since G6 is an input only pin and G7 is the dedicated CKO
clock output pin (crystal clock option) or general purpose in-
put (R/C clock option), the associated bits in the data and
CC
L7
L6
L5
L4
L3
L2
L1
L0
CONFIGURATION
and GND are the power supply pins. All V
Register
MIWU or T3B
MIWU or T3A
MIWU or T2B
MIWU or T2A
MIWU
MIWU
MIWU
MIWU
0
0
1
1
Register
DATA
0
1
0
1
Hi-Z Input
(TRI-STATE Output)
Input with Weak Pull-Up
Push-Pull Zero Output
Push-Pull One Output
Port Set-Up
CC
and GND
8
configuration registers for G6 and G7 are used for special
purpose functions as outlined on the next page. Reading the
G6 and G7 data bits will return zeros.
Note that the chip will be placed in the HALT mode by writing
a “1” to bit 7 of the Port G Data Register. Similarly the chip
will be placed in the IDLE mode by writing a “1” to bit 6 of the
Port G Data Register.
Writing a “1” to bit 6 of the Port G Configuration Register en-
ables the MICROWIRE/PLUS to operate with the alternate
phase of the SK clock. The G7 configuration bit, if set high,
enables the clock start up delay after HALT when the R/C
clock configuration is used.
Port G has the following alternate features:
Port G has the following dedicated functions:
Port C is an 8-bit I/O port. The 40-pin device does not have
a full complement of Port C pins. The unavailable pins are
not terminated. A read operation for these unterminated pins
will return unpredicatable values.
Port I is an 8-bit Hi-Z input port, and also provides the analog
inputs to the A/D converter. The 28-pin device does not have
a full complement of Port I pins. The unavailable pins are not
terminated (i.e. they are floating). A read operation from
these unterminated pins will return unpredictable values.
The user should ensure that the software takes this into ac-
count by either masking out these inputs, or else restricting
the accesses to bit operations only. If unterminated, Port I
pins will draw power only when addressed.
Port D is an 8-bit output port that is preset high when RESET
goes low. The user can tie two or more D port outputs (ex-
cept D2) together in order to get a higher drive.
G6 SI (MICROWIRE Serial Data Input)
G5 SK (MICROWIRE Serial Clock)
G4 SO (MICROWIRE Serial Data Output)
G3 T1A (Timer T1 I/O)
G2 T1B (Timer T1 Capture Input)
G0 INTR (External Interrupt Input)
G7 CKO Oscillator dedicated output or general purpose
G1 WDOUT WATCHDOG and/or Clock Monitor dedi-
G7
G6
input
cated output
FIGURE 4. I/O Port Configurations
CLKDLY
Alternate SK
Config Reg.
HALT
IDLE
Data Reg.
DS012526-5