p87c453ebaa NXP Semiconductors, p87c453ebaa Datasheet - Page 5

• Manufacturer Part Number: p87c453ebaa
• Description: 80c51 8-bit Microcontroller Family 8k/256 Otp/rom, Expanded I/o
• Manufacturer: NXP Semiconductors

Philips Semiconductors
PIN DESCRIPTION
1998 Apr 23
MNEMONIC
V
V
P0.0–0.7
P1.0–P1.7
P2.0–P2.7
P3.0–P3.7
P4.0–P4.3
P4.0–P4.7
P5.0–P5.7
P6.0–P6.7
ODS
IDS
BFLAG
AFLAG
RST
ALE/PROG
PSEN
EA/V
XTAL1
XTAL2
SS
CC
80C51 8-bit microcontroller family
8K/256 OTP/ROM, expanded I/O
PP
PIN NO.
17-10
27-34
36-43
26-19
44-51
59-66
2-9
54
18
36
37
38
39
40
41
42
43
55
56
57
58
35
68
67
53
52
1
TYPE NAME AND FUNCTION
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
O
O
O
O
O
I
I
I
I
I
I
I
I
I
I
I
I
Ground: 0V reference.
Power Supply: This is the power supply voltage for normal, idle, and power-down operation.
Port 0: Port 0 is an open-drain, bidirectional I/O port. Port 0 is also the multiplexed data and low-order
address bus during accesses to external memory. External pull-ups are required during program
verification. Port 0 can sink/source eight LS TTL inputs.
Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. Port 1 receives the low-order address
bytes during program memory verification. Port 1 can sink/source three LS TTL inputs, and drive CMOS
inputs without external pull-ups.
Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 emits the high-order address
bytes during access to external memory and receives the high-order address bits and control signals
during program verification. Port 2 can sink/source three LS TTL inputs, and drive CMOS inputs without
external pull-ups.
Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 can sink/source three LS TTL
inputs, and drive CMOS inputs without external pull-ups. Port 3 also serves the special functions listed
below:
RxD (P3.0): Serial input port
TxD (P3.1): Serial output port
INT0 (P3.2): External interrupt
INT1 (P3.3): External interrupt
T0 (P3.4): Timer 0 external input
T1 (P3.5): Timer 1 external input
WR (P3.6): External data memory write strobe
RD (P3.7): External data memory read strobe
Port 4: Port 4 is an 8-bit bidirectional I/O port with internal pull-ups. Port 4 can sink/source three LS TTL
inputs and drive CMOS inputs without external pull-ups.
Port 5: Port 5 is an 8-bit bidirectional I/O port with internal pull-ups. Port 5 can sink/source three LS TTL
inputs and drive CMOS inputs without external pull-ups.
Port 6: Port 6 is a specialized 8-bit bidirectional I/O port with internal pull-ups. This special port can
sink/source three LS TTL inputs and drive CMOS inputs without external pull-ups. Port 6 can be used in a
strobed or non-strobed mode of operation. Port 6 works in conjunction with four control pins that serve the
functions listed below:
ODS: Output data strobe
IDS: Input data strobe
BFLAG: Bidirectional I/O pin with internal pull-ups
AFLAG: Bidirectional I/O pin with internal pull-ups
Reset: A high on this pin for two machine cycles while the oscillator is running, resets the device. An
internal pull-down resistor permits a power-on reset using only an external capacitor connected to V
Address Latch Enable/Program Pulse: Output pulse for latching the low byte of the address during an
access to external memory. ALE is activated at a constant rate of 1/6 the oscillator frequency except during
an external data memory access, at which time one ALE is skipped. ALE can sink/source three LS TTL
inputs and drive CMOS inputs without external pull-ups. This pin is also the program pulse during EPROM
programming.
Program Store Enable: The read strobe to external program memory. PSEN is activated twice each
machine cycle during fetches from external program memory. However, when executing out of external
program memory, two activations of PSEN are skipped during each access to external program memory.
PSEN is not activated during fetches from internal program memory. PSEN can sink/source eight LS TTL
inputs and drive CMOS inputs without an external pull-up. This pin should be tied low during programming.
Instruction Execution Control/Programming Supply Voltage: When EA is held high, the CPU executes
out of internal program memory, unless the program counter exceeds 1FFFH. When EA is held low, the
CPU executes out of external program memory. EA must never be allowed to float. This pin also receives
the 12.75V programming supply voltage (V
Crystal 1: Input to the inverting oscillator amplifier that forms the oscillator. This input receives the external
oscillator when an external oscillator is used.
Crystal 2: An output of the inverting amplifier that forms the oscillator. This pin should be floated when an
external oscillator is used.
5
PP
) during EPROM programming.
83C453/87C453
Preliminary specification
CC
.