Daewoo DVDP485 Service Manual page 20

PRELIMINARY, SUBJECT TO CHANGE WITHOUT NOTICE
PORT3 I/O
[7:0]
PORT4 I/O
[7:0]
PORT5 I/O
[7:0]
FWR# O
4.2.1
External Micro-controller Mode
Pin name
ALE
LATS
SAD[7:0]
The above information is the exclusive intellectual property of Cheertek Inc. and shall not be disclosed, distributed or reproduced without permission from Cheertek Inc.
Port3 is an 8-bit bi-directional I/O port with internal
pull-up.
Port3 also serve following special functions:
P3.0 RXD1 (serial input port)
P3.1 TXD1 (serial output port)
P3.2 IR input connecting to IR receiver
P3.3: GPA6, general purpose IO bus A bit 6, initial in
input state
P3.4 T0 (timer 0 external input)
P3.5 T1 (timer 1 external input)
P3.6 WR# (external data memory write)
P3.7 RD# (external data memory read)
Port4 is an 8-bit bi-directional I/O port with internal
pull-up. It can be used for bank selection of external
program and data memories, internally latched with
ALE.
Port5 is an 8 -bit bi-directional I/O port, default in
input state.
Flash write enable output
Type Description
I Address latch enable. It is used to latch the low byte address of SAD[7:0] as
LATS=0.
I Low byte address conveying type select, input only.
LATS=0, mux with SAD[7:0];
LATS=1, conveyed on SA[7:0].
I/O When ALE is active (ALE=1), it is the low byte of the address. And it is
time-multiplexed with the data byte being written(WR# active) or
read(RD# active).
CTK CONFIDENTIAL, NO DISCLOSURE
P3.3: INTM#, output
P3.6: WR#, input
P3.7: RD#, input
Copyright (C) 2003 Cheertek Inc. All Rights Reserved.
CT908