1

Features

Description

The AT89C4051 is a low-voltage, high-performance CMOS 8-bit microcomputer with

4K bytes of Flash programmable and erasable read-only memory (PEROM). The

device is manufactured using Atmel’s high-density nonvolatile memory technology and

is compatible with the industry-standard MCS-51 instruction set. By combining a ver-

satile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C4051 is a powerful

microcomputer which provides a highly-flexible and cost-effective solution to many

embedded control applications.

The AT89C4051 provides the following standard features: 4K bytes of Flash,

128 bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five-vector, two-level inter-

rupt architecture, a full duplex serial port, a precision analog comparator, on-chip

oscillator and clock circuitry. In addition, the AT89C4051 is designed with static logic

for operation down to zero frequency and supports two software-selectable power sav-

ing modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters,

serial port and interrupt system to continue functioning. The power-down mode saves

the RAM contents but freezes the oscillator disabling all other chip functions until the

next hardware reset.

Pin Configuration

PDIP/SOIC

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

RST/VPP

(RXD) P3.0

(TXD) P3.1

XTAL2

XTAL1

(INT0) P3.2

(INT1) P3.3

(TO) P3.4

(T1) P3.5

GND

VCC

P1.7

P1.6

P1.5

P1.4

P1.3

P1.2

P1.1 (AIN1)

P1.0 (AIN0)

P3.7

Rev. 1001D–06/01

8-bit

Microcontroller

with 4K Bytes

Flash

AT89C4051