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 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 |
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/Counters:Two, 16-Bit
Package of Atmel AT89C51 Microcontroller:
1 x Atmel AT89C51 Microcontroller