Microcontroller
Microcontroller is a single chip computer that is embedded into systems to function as processing and controlling.
A microcontroller basically contains one or more following components:
- Central processing unit (CPU)
- Random Access Memory (RAM)
- Read Only Memory (ROM)
- Input/output ports
- Timers and Counters Interrupt Controls
- Analog to digital converters
- Digital analog converters Serial interfacing ports
- Oscillatory circuits
The general block diagram of microcontroller is shown in Figure.
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| General Block Diagram of Microcontroller |
- CPU (Central Processing Unit): CPU is called as brain of a microcontroller and it is responsible for fetching the instruction, decodes it, then finally executed. CPU is connected to each and every part of a microcontroller as a single system. The main function of CPU is fetching and decoding instructions.
- Memory : Memory is used to store users or systems data/program. Every microcontroller has a some sort of memory such as RAM, ROM or EEPROM or flash RAM for storing program source codes.
- Parallel Input/output ports : Parallel input / output ports are used to interface different I/O devices such as LCD’S, LED’S, printers, memories, etc to a microcontroller.
- Serial ports: Serial ports are used to interfaces serial devices or peripherals with microcontroller like parallel ports.
- Timers/counters: Every microcontroller has one or more than one timer/counters to provide timing and counting operation inside the microcontroller. The main operations of Timers/counters are provide timing to clock functions, modulations, pulse generations, frequency measuring, making oscillations, etc. and also used for counting external pulses.
- Analog to Digital Converter (ADC) : ADC converters are used to convert the analog signal to digital signal. The input signal to ADC converter must be in analog nature e.g. output from the different sensor and the output from ADC unit are in digital form equivalent to analog input. The digital output can be used for various digital applications such as measurement devices, displaying some values on LCD/LED after calculation.
- Digital to Analog Converter (DAC) : DAC is used to convert the digital signal into analog signal of desired magnitude. It is used for controlling analog devices like DC motors, stepper motors, servo motors etc.
- Interrupt control : The interrupt control is used to interrupt the program may be an external interrupt which activated by external device using interrupt pin or internal interrupt by using interrupt instruction in a program.
- Special function block : Most of the microcontrollers are used only for some special applications such radar system, space systems or robotics, which containing additional ports to perform some special operations and considered as special function block such as SPI, I2C interface, DMA etc.