Philips Semiconductors Product data
P87C554
80C51 8-bit microcontroller – 12 clock operation
16K/512 OTP/RAM, 8 channel 10-bit A/D, I
2
C, PWM,
capture/compare, high I/O
2002 Mar 25
4
PIN DESCRIPTION
Table 1. Pin description
MNEMONIC PIN NO. TYPE NAME AND FUNCTION
V
DD
2 I Digital Power Supply: Positive voltage power supply pin during normal operation, idle and
power-down mode.
STADC 3 I Start ADC Operation: Input starting analog to digital conversion (ADC operation can also be
started by software).
PWM0 4 O Pulse Width Modulation: Output 0.
PWM1 5 O Pulse Width Modulation: Output 1.
EW 6 I Enable Watchdog Timer: Enable for T3 watchdog timer and disable power-down mode.
P0.0-P0.7 57-50 I/O Port 0: Port 0 is an 8-bit 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 is also used to input the code byte during
programming and to output the code byte during verification.
P1.0-P1.7
16-23 I/O Port 1: 8-bit I/O port. Alternate functions include:
16-21 I/O (P1.0-P1.5): Programmable I/O port pins.
22-23 I/O (P1.6, P1.7): Open drain port pins.
16-19 I CT0I-CT3I (P1.0-P1.3): Capture timer input signals for timer T2.
20 I T2 (P1.4): T2 event input.
21 I RT2 (P1.5): T2 timer reset signal. Rising edge triggered.
22 I/O SCL (P1.6): Serial port clock line I
2
C-bus.
23 I/O SDA (P1.7): Serial port data line I
2
C-bus.
Port 1 has four modes selected on a per bit basis by writing to the P1M1 and P1M2 registers as
follows:
P1M1.x P1M2.x Mode Description
0 0 Pseudo–bidirectional (standard c51 configuration; default)
0 1 Push-Pull
1 0 High impedance
1 1 Open drain
Port 1 is also used to input the lower order address byte during EPROM programming and
verification. A0 is on P1.0, etc.
P2.0-P2.7 39-46 I/O Port 2: 8-bit programmable I/O port.
Alternate function: High-order address byte for external memory (A08-A15). Port 2 is also used to
input the upper order address during EPROM programming and verification. A8 is on P2.0, A9 on
P2.1, through A13 on P2.5.
Port 2 has four output modes selected on a per bit basis by writing to the P2M1 and P2M2 registers
as follows:
P2M1.x P2M2.x Mode Description
0 0 Pseudo–bidirectional (standard c51 configuration; default)
0 1 Push-Pull
1 0 High impedance
1 1 Open drain
P3.0-P3.7
24-31 I/O Port 3: 8-bit programmable I/O port. Alternate functions include:
24 RxD(P3.0): Serial input port.
25 TxD (P3.1): Serial output port.
26 INT0 (P3.2): External interrupt.
27 INT1 (P3.3): External interrupt.
28 T0 (P3.4): Timer 0 external input.
29 T1 (P3.5): Timer 1 external input.
30 WR (P3.6): External data memory write strobe.
31 RD (P3.7): External data memory read strobe.
Port 3 has four modes selected on a per bit basis by writing to the P3M1 and P3M2 registers as
follows:
P3M1.x P3M2.x Mode Description
0 0 Pseudo–bidirectional (standard c51 configuration; default)
0 1 Push–Pull
1 0 High impedance
1 1 Open drain
