87C654 Philips Semiconductors, 87C654 Datasheet - Page 7

• Manufacturer Part Number: 87C654
• Description: 80C51 8-bit microcontroller 8K/16K/ 256 OTP/ I2C
• Manufacturer: Philips Semiconductors

Philips Semiconductors
PIN DESCRIPTIONS
NOTE:
To avoid “latch-up” effect at power-on, the voltage on any pin at any time must not be higher than V
1996 Aug 16
V
V
P0.0–0.7
P1.0–P1.7
P1.6
P1.7
P2.0–P2.7
P3.0–P3.7
RST
ALE/PROG
PSEN
EA/V
XTAL1
XTAL2
MNEMONIC
SS
CC
CMOS single-chip 8-bit microcontroller
PP
39–32 43–36
21–28 24–31
10–17
DIP
1–8
20
40
10
11
12
13
14
15
16
17
30
29
31
19
18
7
8
9
PIN NUMBER
13–19
LCC
2–9
11,
22
44
13
14
15
16
17
18
19
10
33
32
35
21
20
11
8
9
40–44,
37–30
18–25
7–13
QFP
1–3
16
38
10
12
13
27
26
29
15
14
11
5,
2
3
5
7
8
9
4
TYPE
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
NAME AND FUNCTION
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 pins that have 1s written to them
float and can be used as high-impedance inputs. Port 0 is also the multiplexed low-order
address and data bus during accesses to external program and data memory. In this
application, it uses strong internal pull-ups when emitting 1s. Port 0 also outputs the code
bytes during program verification in the 87C654. External pull-ups are required during
program verification.
Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups, except P1.6 and P1.7
which are open drain. Port 1 pins that have 1s written to them are pulled high by the internal
pull-ups and can be used as inputs. As inputs, port 1 pins that are externally pulled low will
source current because of the internal pull-ups. (See DC Electrical Characteristics: I
Port 1 also receives the low-order address byte during program memory verification.
Alternate functions include:
Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 pins that have 1s
written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,
port 2 pins that are externally being pulled low will source current because of the internal
pull-ups. (See DC Electrical Characteristics: I
during fetches from external program memory and during accesses to external data memory
that use 16-bit addresses (MOVX @DPTR). In this application, it uses strong internal
pull-ups when emitting 1s. During accesses to external data memory that use 8-bit
addresses (MOV @Ri), port 2 emits the contents of the P2 special function register.
Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that have 1s
written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,
port 3 pins that are externally being pulled low will source current because of the pull-ups.
(See DC Electrical Characteristics: I
family, as listed below:
Reset: A high on this pin for two machine cycles while the oscillator is running, resets the
device. An internal diffused resistor to V
capacitor to V
Address Latch Enable/Program Pulse: Output pulse for latching the low byte of the
address during an access to external memory. In normal operation, ALE is emitted at a
constant rate of 1/6 the oscillator frequency, and can be used for external timing or clocking.
Note that one ALE pulse is skipped during each access to external data memory. This pin is
also the program pulse input (PROG) during EPROM programming.
Program Store Enable: The read strobe to external program memory. When the 87C654 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.
External Access Enable/Programming Supply Voltage: EA must be externally held low to
enable the device to fetch code from external program memory locations 0000H and 3FFFH.
If EA is held high, the device executes from internal program memory unless the program
counter contains an address greater than 3FFFH. This pin also receives the 12.75V
programming supply voltage (V
Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator
circuits.
Crystal 2: Output from the inverting oscillator amplifier.
SCL: I
SDA: I
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
2
2
C-bus serial port clock line.
C-bus serial port data line.
CC
.
7
PP
) during EPROM programming.
IL
). Port 3 also serves the special features of the 80C51
SS
permits a power-on reset using only an external
IL
). Port 2 emits the high-order address byte
CC
+ 0.5V or V
SS
– 0.5V, respectively.
Product specification
87C654
IL
).