Description

Atmel AT89C51 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 timers & 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 comparators	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 timers	0
No. Of 16-bit Timers	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