P89C738ABB View Datasheet(PDF) - Philips Electronics
Part Name
Description
MFG CO.
'P89C738ABB' PDF : 64 Pages View PDF
Philips Semiconductors
8-bit Flash microcontrollers
Product specification
P89C738; P89C739
11 I/O FACILITIES
The P89C738 has 4 and P89C739 has 6 8-bit ports.
Ports 0 to 3 are the same as in the 80C51, with the
exception of the additional function of Port 1. Port lines
P1.0 and P1.1 may be used as inputs for Timer 2, P1.1
may also be used as an additional (third) external interrupt
request input.
Ports 0, 1, 2, and 3 perform the following alternative
functions:
Port 0 Provides the multiplexed low-order address and
data bus used for expanding the P89C738 with
standard memories and peripherals.
Port 1 Pins can be configured individually to provide:
external interrupt request input (external
interrupt 2); external inputs for Timer/counter 2.
Port 2 Provides the high-order address bus when
expanding the P89C738 with external program
memory and/or external data memory.
Port 3 Pins can be configured individually to provide:
external interrupt request inputs (external
interrupt 0/1); external inputs for Timer/counter 0
and Timer/counter 1; Serial Port receiver input and
transmitter output control signals to read and write
external data memory.
Bits which are not used for the alternative functions may be
used as normal bidirectional I/O pins. The generation or
use of a Port 1 or Port 3 pin as an alternative function is
carried out automatically by the P89C738 provided the
associated SFR bit is HIGH. Otherwise the port pin is held
at a logical LOW level.
handbook, full pagewidth
Q
from port latch
input data
read port pin
2 oscillator
periods
strong pull-up
p1
n
INPUT
BUFFER
VDD
p2
p3
I/O PIN
I1
MGG025
Fig.15 I/O buffers in the P89C738; P89C739 (Ports 1, 2, 3, 4 and 5).
1998 Apr 07
25
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