sm89516 SyncMOS Technologies,Inc, sm89516 Datasheet - Page 10

• Manufacturer Part Number: sm89516
• Description: 8-bits Micro-controller With 64kb Flash & 1kb Ram Embedded
• Manufacturer: SyncMOS Technologies,Inc

1.3 I/O Pin Configuration
The ports 1, 2 and 3 of standard 8051 have internal pull-up resistor, and port 0 has open-drain outputs. Each I/O pin
can be used independently as an input or an output. For I/O ports to be used as an input pin, the port bit latch must
contain a ‘1’ which turns off the output driver FET. Then for port 1, 2 and 3 port pin is pulled high by a weak internal
pull-up, and can be pulled low by an external source. The port 0 has open-drain outputs which means its pull-ups are
not active during normal port operation. Writing ‘1’ to the port 0 bit latch will causing bit floating so that it can be used as
a high-impedance input.
The port 4 used as GPIO will has the same function as port 1, 2 and 3.
2. Port 4 for PLCC or QFP package :
The bit addressable port 4 is available with PLCC or QFP package. The port 4 has only 4 pins and its port address is
located at 0D8H. The function of port 4 is the same as the function of port 1, port 2 and port 3.
Port4 (P4, $D8)
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M010Ver:B SM89516
The bit 7(WDR) of SCONF is Watch Dog Timer Reset bit. It will be set to 1 when reset signal generated
by WDT overflow. User should check WDR bit whenever un-predicted reset happened.
ALEI: ALE output inhibit bit, to reduce EMI
Read / Write:
Reset value:
The bit 3, bit 2, bit 1, bit 0 output the setting to pin P4.3, P4.2, P4.1, P4.0 respectively.
The port 4 output buffers can sink 20mA and can drive LED display directly.
SyncMOS Technologies International, Inc.
Unused
bit-7
*
-
Unused
*
-
Unused
*
-
Unused
10
*
-
P4.3
R/W
1
With 64KB flash & 1KB RAM embedded
P4.2
R/W
1
8-Bits Micro-controller
P4.1
R/W
1
SM89516
P4.0
bit-0
R/W
1
05/2009