Micro Controllers

Micro Controller :

A micro-controller (sometimes abbreviated µC, uC or MCU) is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Micro-controllers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications.

μC Basics

8051 μC

8051 Micro-controller

8051-An Application Based Introduction_Chris BraithWaite

ARM system onchip Architecture_Steve Furber

A few micro-controllers may utilize four-bit expressions and work at clock rate frequencies, which usually include:

• An 8 or 16 bit microprocessor.
• A little measure of RAM.
• Programmable ROM and flash memory.
• Parallel and serial I/O.
• Timers and signal generators.
• Analog to Digital and Digital to Analog conversion.

            Micro-controllers usually must have low-power requirements since many devices they control are battery-operated. Micro-controllers are used in many consumer electronics, car engines, computer peripherals and test or measurement equipment. And these are well suited for long lasting battery applications. The majority of micro-controllers in use today are embedded in other machinery.

        The micro-controllers are characterized regarding bus-width, instruction set, and memory structure. For the same family, there may be different forms with different sources. This article is going to describe some of the basic types of the Micro-controller that newer users may not know about.

Types of Micro-controller:

             The types of micro-controller is shown in figure, they are characterized by their bits, memory architecture, memory/devices and instruction set. Let’s discuss briefly about it.

Refer this for more types : http://typesofmicrocontrollers.com

Bits:

The bits in micro-controller are 8-bits, 16-bits and 32-bits micro-controller.

In 8-bit micro-controller, the point when the internal bus is 8-bit then the ALU is performs the arithmetic and logic operations. The examples of 8-bit micro-controllers are Intel 8031/8051, PIC1x and Motorola MC68HC11 families.

The 16-bit micro-controller performs greater precision and performance as compared to 8-bit. For example 8 bit micro-controllers can only use 8 bits, resulting in a final range of 0×00 – 0xFF (0-255) for every cycle. In contrast, 16 bit micro-controllers with its 16 bit data width has a range of 0×0000 – 0xFFFF (0-65535) for every cycle. A longer timer most extreme worth can likely prove to be useful in certain applications and circuits. It can automatically operate on two 16 bit numbers. Some examples of 16-bit micro-controller are 16-bit MCUs are extended 8051XA, PIC2x, Intel 8096 and Motorola MC68HC12 families.

The 32-bit micro-controller uses the 32-bit instructions to perform the arithmetic and logic operations. These are used in automatically controlled devices including implantable medical devices, engine control systems, office machines, appliances and other types of embedded systems. Some examples are Intel/Atmel 251 family, PIC3x.

Memory Devices:

The memory devices are divided into two types, they are

• Embedded memory micro-controller
• External memory micro-controller

Embedded memory micro-controller: When an embedded system has a micro-controller unit that has all the functional blocks available on a chip is called an embedded micro-controller  For example, 8051 having program & data memory, I/O ports, serial communication, counters and timers and interrupts on the chip is an embedded micro-controller.

External Memory Micro-controller: When an embedded system has a micro-controller unit that has not all the functional blocks available on a chip is called an external memory micro-controller  For example, 8031 has no program memory on the chip is an external memory micro-controller.

Instruction Set:

The instruction sets are classified as CISC and RISC.

CISC: CISC is a Complex Instruction Set Computer. It allows the programmer to use one instruction in place of many simpler instructions.

RISC: The industry trend for microprocessor design is for Reduced Instruction Set Computers (RISC) designs. It allows each instruction to operate on any register or use any addressing mode and simultaneous access of program and data.

Example for CISC and RISC:

CISC:	Mov AX, 4	RISC:		Mov AX, 0
	Mov BX, 2			Mov BX, 4
	ADD BX, AX			Mov CX, 2
			Begin	ADD AX, BX
			Loop	Begin

From above example, RISC systems shorten execution time by reducing the clock cycles per instruction and CISC systems shorten execution time by reducing the number of instructions per program. The RISC provides a higher performance in computing than the CISC.

Memory Architecture:

Memory architecture of micro-controller are two types, they are namely:

• Harvard memory architecture micro-controller
• Princeton memory architecture micro-controller

Harvard Memory Architecture Micro-controller: The point when a micro-controller unit has a dissimilar memory address space for the program and data memory, the micro-controller has Harvard memory architecture in the processor.

Princeton Memory Architecture Micro-controller: The point when a micro-controller has a common memory address for the program memory and data memory, the micro-controller has Princeton memory architecture in the processor.

Applications of Micro-controllers:

Micro-controller has many applications electronic equipment’s:

• Mobile Phones
• Auto Mobiles
• Washing Machines
• Cameras
• Security Alarms