s87c751-5a28 NXP Semiconductors, s87c751-5a28 Datasheet - Page 5

• Manufacturer Part Number: s87c751-5a28
• Description: 80c51 8-bit Microcontroller Family 2k/64 Otp/rom, I2c, Low Pin Count
• Manufacturer: NXP Semiconductors

1. When P0.2 is at or close to 0V it may affect the internal ROM operation. We recommend that P0.2 be tied to V
Philips Semiconductors
PIN DESCRIPTIONS
NOTE:
1998 May 01
MNEMONIC
V
V
P0.0–P0.2
P1.0–P1.7
P3.0–P3.7
RST
X1
X2
SS
CC
80C51 8-bit microcontroller family
2K/64 OTP/ROM, I
(e.g., 2k ).
SSOP
13–20
23–21
DIP/
5–1,
8–6
12
24
18
19
20
10
11
6
7
8
7
8
9
PIN NO.
15–20,
6, 4–1,
23, 24
27–25
LCC
9–7
14
28
20
23
24
13
12
11
7
8
9
8
9
TYPE
N/A
2
I/O
I/O
I/O
I/O
I/O
O
I
I
I
I
I
I
I
I
I
C, low pin count
Circuit Ground Potential
Supply voltage during normal, idle, and power-down operation.
Port 0: Port 0 is a 3-bit open-drain, bidirectional port. Port 0 pins that have 1s written to them float,
and in that state can be used as high-impedance inputs. Port 0 also serves as the serial I
interface. When this feature is activated by software, SCL and SDA are driven low in accordance
with the I
subsystem presents a 0. The state of the pin can always be read from the port register by the
program.
To comply with the I
electrical characteristics listed in the tables that follow. While these differ from “standard TTL”
characteristics, they are close enough for the pins to still be used as general-purpose I/O in
non-I
memory as follows:
V
OE/PGM (P0.1) – Input which specifies verify mode (output enable) or the program mode.
OE/PGM = 1 output enabled (verify mode).
OE/PGM = 0 program mode.
ASEL (P0.0) – Input which indicates which bits of the EPROM address are applied to port 3.
ASEL = 0 low address byte available on port 3.
ASEL = 1 high address byte available on port 3 (only the three least significant bits are used).
SDA (P0.1) – I
SCL (P0.0) – I
Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. 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
mode and accepts as inputs the value to program into the selected address during the program
mode. Port 1 also serves the special function features of the 80C51 family as listed below:
INT0 (P1.5): External interrupt.
INT1 (P1.6): External interrupt.
T0 (P1.7): Timer 0 external input.
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
be programmed (or verified). The 11-bit address is multiplexed into this port as specified by
P0.0/ASEL.
Reset: A high on this pin for two machine cycles while the oscillator is running, resets the device.
An internal diffused resistor to V
V
the device in the programming state allowing programming address, data and V
programming or verification purposes. The RESET serial sequence must be synchronized with the
X1 input.
Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator circuits.
X1 also serves as the clock to strobe in a serial bit stream into RESET to place the device in the
programming state.
Crystal 2: Output from the inverting oscillator amplifier.
PP
CC
. After the device is reset, a 10-bit serial sequence, sent LSB first, applied to RESET, places
(P0.2) – Programming voltage input. (See Note 1.)
2
C applications. Port 0 also provides alternate functions for programming the EPROM
2
C protocol. These pins are driven low if the port register bit is written with a 0 or if the I
2
2
C clock.
C data.
IL
). Port 3 also functions as the address input for the EPROM memory location to
2
C specification, P0.0 and P0.1 are open drain bidirectional I/O pins with the
IL
). Port 1 serves to output the addressed EPROM contents in the verify
5
SS
permits a power-on RESET using only an external capacitor to
NAME AND FUNCTION
83C751/87C751
CC
via a small pullup
PP
Product specification
to be applied for
2
C
2
C