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IS80C52
IS80C32
6
Integrated Silicon Solution, Inc. — 1-800-379-4774
MC004-1D
11/19/98
ISSI
Symbol
PDIP
PLCC
PQFP
I/O
Name and Function
P3.0-P3.7
10-17
11, 13-19
5, 7-13
I/O
Port 3: Port 3 is an 8-bit bidirectional I/O port with internal
pullups. Port 3 pins that have 1s written to them are pulled high
by the internal pullups and can be used as inputs. As inputs,
Port 3 pins that are externally pulled low will source current
because of the internal pullups. (See DC Characteristics: IIL).
Port 3 also serves the special features of the IS80C51/31, as
listed below:
10
11
5
I
RxD (P3.0): Serial input port.
11
13
7
O
TxD (P3.1): Serial output port.
12
14
8
I
INT0
INT0 (P3.2): External interrupt 0.
13
15
9
I
INT1
INT1 (P3.3): External interrupt 1.
14
16
10
I
T0 (P3.4): Timer 0 external input.
15
17
11
I
T1 (P3.5): Timer 1 external input.
16
18
12
O
WR
WR (P3.6): External data memory write strobe.
17
19
13
O
RD
RD (P3.7): External data memory read strobe.
PSEN
29
32
26
O
Program Store Enable: The read strobe to external program
memory. When the device is executing code from the external
program memory,
PSEN is activated twice each machine
cycle except that two
PSEN activations are skipped during
each access to external data memory.
PSEN is not activated
during fetches from internal program memory.
RST
9
10
4
I
Reset: A high on this pin for two machine cycles while the
oscillator is running, resets the device. An internal MOS
resistor to GND permits a power-on reset using only an
external capacitor connected to Vcc.
XTAL 1
19
21
15
I
Crystal 1: Input to the inverting oscillator amplifier and
input to the internal clock generator circuits.
XTAL 2
18
20
14
O
Crystal 2: Output from the inverting oscillator amplifier.
GND
20
22
16
I
Ground: 0V reference.
Vcc
40
44
38
I
Power Supply: This is the power supply voltage for operation.
Table 1. Detailed Pin Description
(continued)