AT89C51 is an 8-bit microcontroller and belongs to Atmel’s 8051 family. ATMEL 89C51 has 4KB of Flash programmable and erasable read only memory (PEROM) and 128 bytes of RAM. It can be erased and program to a maximum of 1000 times.

In 40 pin AT89C51, there are four ports designated as P1, P2, P3 and P0. All these ports are 8-bit bi-directional ports, i.e., they can be used as both input and output ports. Except P0 which needs external pull-ups, rest of the ports have internal pull-ups. When 1s are written to these port pins, they are pulled high by the internal pull-ups and can be used as inputs. These ports are also bit addressable and so their bits can also be accessed individually.

Port P0 and P2 are also used to provide low byte and high byte addresses, respectively, when connected to an external memory. Port 3 has multiplexed pins for special functions like serial communication, hardware interrupts, timer inputs and read/write operation from external memory. AT89C51 has an inbuilt UART for serial communication. It can be programmed to operate at different baud rates. Including two time & hardware interrupts, it has a total of six interrupts.

Features of Atmel AT89C51 Microcontroller:

CPU

8-bit 8051 family

Architecture

8051

Program Memory Size (Kbytes)

4K Flash

RAM (bytes)

128

EEPROM/HEF

Nil

Pin Count

40

Max. CPU Speed (MHz)

24

Peripheral Pin select (PPS)

No

Internal Oscillator

No

No. Of comparato

2

No. Of Operational Amplifier

0

No. Of ADC channels

Nil

Max ADC Resolution (bits)

NA

ADC with Computation

No

Number of DAC Converter

0

Max DAC resolution

0

Internal Voltage Reference

NA

Zero Cross Detect

No

No. Of 8-bit time

0

No. Of 16-bit Time

2

Signal Measurement Timer

0

Hardware Limit Timer

0

No. Of PWM outputs

0

Max PWM resolution

NA

Angular Timer

No

Math Accelerator

No

No. Of UART module

1

No. Of SPI Module

0

No. Of I2C module

0

No. Of USB Module

0

Windowed Watchdog Timer (WWDT)

No

CRC/Scan

No

Numerically Controlled Oscillator

0

Cap. Touch Channels

NA

Segment LCD

0

Minimum Operating Temperature (*C)

-55

Maximum Operating Temperature (*C)

125

Minimum Operating Voltage (V)

4

Maximum Operating Voltage (V)

5.5

High Voltage Capable

No

Specifications of Atmel AT89C51 Microcontroller:

Flash Memory : 4K Bytes

CPU:8-Bit

Maximum Operating Voltage:6.6V

Maximum Ocsillator Frequency: 0 Hz to 24 MHz

Internal RAM:128 x 8-Bit

Programmable I/O Lines:32

Timer/Counte:Two, 16-Bit

Package of Atmel AT89C51 Microcontroller:

1 x Atmel AT89C51 Microcontroller