cop87l88rg National Semiconductor Corporation, cop87l88rg Datasheet - Page 6

• Manufacturer Part Number: cop87l88rg
• Description: 8-bit One-time Programmable Microcontroller With Kbytes Program Memory
• Manufacturer: National Semiconductor Corporation

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Pin Descriptions
V
CKI is the clock input This can come from an R C generat-
ed oscillator or a crystal oscillator (in conjunction with
CKO) See Oscillator Description section
RESET is the master reset input See Reset Description
section
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
reserved for the input pins of each I O port (See the memo-
ry 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 individually configured under software control as
shown below
CONFIGURATION
CC
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and GND are the power supply pins
Register
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
FIGURE 4 I O Port Configurations
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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 (MIWU) on all eight
pins L1 is used for the UART external clock L2 and L3 are
used for the UART transmit and receive 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 two dedicated output pins (G1 and 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 oscil-
lator mask option selected With the crystal oscillator option
selected 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
L0
L1
L2
L3
L4
L5
L6
L7
MIWU
MIWU or CKX
MIWU or TDX
MIWU or RDX
MIWU or T2A
MIWU or T2B
MIWU or T3A
MIWU or T3B
TL DD12860 – 6