COP87L88GG Datasheet, PDF (7/42 Pages) National Semiconductor (TI) – 8-Bit One-Time Programmable OTP Microcontroller with UART and Three Multi-Function Timers

Pin Descriptions
V_CC and GND are the power supply pins All V_CC and GND
pins must be connected
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 DATA
Register
Register
Port Set-Up
0
0
Hi-Z Input
(TRI-STATE Output)
0
1
Input with Weak Pull-Up
1
0
Push-Pull Zero Output
1
1
Push-Pull One Output
PORT L is an 8-bit I O port All L-pins have Schmitt triggers
on the inputs
The Port L supports Multi-Input Wake Up 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
The Port L has the following alternate features
L0 MIWU
L1 MIWU or CKX
L2 MIWU or TDX
L3 MIWU or RDX
L4 MIWU or T2A
L5 MIWU or T2B
L6 MIWU or T3A
L7 MIWU or T3B
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 selected
G7 serves as the dedicated output pin for the CKO clock
output With the single-pin R C oscillator mask option se-
lected 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
input (R C clock option) the associated bits in the data and
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
FIGURE 4 I O Port Configurations
TL DD 12532 – 5
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