What are microcontrollers? Electronics built into one single chip capable of controlling an elevator, a refrigerator, a washing machine, etc,... Its all left to you to decide what you wanted to do and dump your instructions for getting your job done. For getting all this done you just need a PC, a program (your instructions), and a simple device to transfer your code from the PC to the chip. I don't think it is complicated!
The microcontroller executes the program loaded in its Flash memory. This is the so called executable code comprised of seemingly meaningless sequence of zeros and ones. It is organized in 12-, 14- or 16-bit wide words, depending on the microcontroller’s architecture. Every word is considered by the CPU as a command being executed during the operation of the microcontroller.
Types of Microcontroller
Microcontrollers are divided into categories according to their memory, architecture, bits and instruction sets. So let’s discuss types of microcontrollers:-1. Bits:
- 8 bits microcontroller executes logic & arithmetic operations. Examples of 8 bits micro controller is Intel 8031/8051.
- 16 bits microcontroller executes with greater accuracy and performance in contrast to 8-bit. Example of 16 bit microcontroller is Intel 8096.
- 32 bits microcontroller is employed mainly in automatically controlled appliances such as office machines, implantable medical appliances, etc. It requires 32-bit instructions to carry out any logical or arithmetic function.
- External Memory Microcontroller – When an embedded structure is built with a microcontroller which does not comprise of all the functioning blocks existing on a chip it is named as external memory microcontroller. For illustration- 8031 microcontroller does not have program memory on the chip.
- Embedded Memory Microcontroller – When an embedded structure is built with a microcontroller which comprise of all the functioning blocks existing on a chip it is named as embedded memory microcontroller. For illustration- 8051 microcontroller has all program & data memory, counters & timers, interrupts, I/O ports and therefore its embedded memory microcontroller.
- CISC- CISC means complex instruction set computer, it allows the user to apply 1 instruction as an alternative to many simple instructions.
- RISC- RISC means Reduced Instruction Set Computers. RISC reduces the operation time by shortening the clock cycle per instruction.
- Harvard Memory Architecture Microcontroller
- Princeton Memory Architecture Microcontroller
Peripheral Interface Controller (PIC) provided by Micro-chip Technology to categorize its solitary chip microcontrollers. These appliances have been extremely successful in 8 bit micro-controllers. The foremost cause behind it is that Micro-chip Technology has been constantly upgrading the appliance architecture and included much required peripherals to the micro-controller to go well with clientele necessities. PIC microcontrollers are very popular amid hobbyists and industrialists; this is only cause of wide availability, low cost, large user base & serial programming capability.
PIC Microcontroller Architecture:
The architecture of the 8 bit PIC microcontrollers can be categorized as below –
- Base Line Architecture – In the base-line architecture PIC microcontrollers of PIC10F family is included, other than that a fraction of PIC12 & PIC16 families are also included. These gadgets make use of 12 bit program word architecture with six to twenty-eight pin package alternatives. Briefly defined attribute set of baseline architecture allows the most lucrative product solutions. This architecture is perfect for battery enabled gadgets. The PIC10F200 series is another reasonably priced 8 bit flash micro-controller with a 6 pin package.
- Mid Range Architecture – In this midline member of PIC12 & PIC16 families are added that attribute 14 bit program word architecture. The midrange PIC16 gadgets proffer a broad variety of package alternatives (from 8 to 64 package), with low to high levels of peripheral incorporation. This PIC16 appliance attributes a variety of analog, digital & serial peripherals, like- SPI, USART, I2C, USB, LCD & A/D converters. The mid-range PIC16 micro-controllers have suspended controlling ability with an eight level hardware load.
- High Performance Architecture – The high performance architecture included the PIC18 family of appliances. These micro-controllers make use of 16 bit program word architecture along with 18 to 100 pin package alternatives. The PIC18 appliances are high performance micro-controllers with incorporated Analog to Digital converters. All PIC18 micro-controllers integrate a highly developed RISC architecture that supports flash appliances. The PIC18 has improved foundation attributes, 32 level deep load and several inner and exterior interrupts.
AVR also known as Advanced Virtual RISC, is a customized Harvard architecture 8 bit RISC solitary chip micro-controller. It was invented in the year 1966 by Atmel. Harvard architecture signifies that program & data are amassed in different spaces and are used simultaneously. It was one of the foremost micro-controller families to employ on-chip flash memory basically for storing program, as contrasting to one time programmable EPROM, EEPROM or ROM, utilized by other micro-controllers at the same time. Flash memory is a non-volatile (constant on power down) programmable memory.
AVR microcontrollers’ architecture was developed by Alf-Egil Bogen and Vegard Wollan. The name AVR is derived from the names of the architecture developers of the microcontroller. The AT90S8515 was the foremost micro-controller which was AVR architecture based; on the other hand the foremost micro-controller to strike the commercial marketplace was AT90S1200 which was launched in the year 1997.
The SRAM, Flash and EEPROM all are incorporated on a single chip, thereby eliminating the requirement of any other external memory in maximum devices. Several appliances comprise of parallel external bus alternative, so as to add extra data memory gadgets. Approximately all appliances, except TinyAVR chips comprise serial interface, which is used to link large serial Flash & EEPROMs chips.
ARM is the name of a company that designs micro-processors architecture. It is also engaged in licensing them to the producers who fabricate genuine chips. In actuality ARM is a 32 bit genuine RISC architecture. It was initially developed in the year 1980 by Acorn Computers Ltd. This ARM base microprocessor does not have on-board flash memory. ARM is particularly designed for micro-controller devices, it is simple to be trained and make use of, however powerful enough for the most challenging embedded devices.
The ARM architecture is a 32 bit RISC processor developed by ARM Ltd. Owing to its power-saving attributes, ARM central processing units are prevailing in the mobile electronics marketplace, where less power expenditure is a vital design aim. ARM architecture comprise of the underneath RISC elements:-
- Maximum single cycle functioning
- Constant 16×32 bit register file.
- Load or store architecture.
- Preset instruction width of 32 bits so as to simplify pipe-lining and decoding, at minimized code density.
- For misaligned memory access there is no support.