Pravin Kumar joy
PRAVIN KUMAR JOY
GOD IS GOOD
Mr.K.Praveen kumar he was born in 1996 in ramanathapuram.He had his studies at syed hameetha arts and science college,kilakarai.He is become a scientist.He was awarded INSPIRE AWARD(2009&2010),VEETUKKORU VINGANI AWARD 2012 for his contribution in BIKE PASSWORD KEY.He was best cadet in NSS and YRC.
Microcontrollers (MCUs)
Introduction: The situation we find ourselves today in the field of microcontrollers has its beginnings in the development of technology of integrated circuit. It enabled us to store hundreds of thousands of transistor into one chip, which was a precondition for the manufacturer of microprocessors. The first computers were may by adding external peripherals, such as memory, input/output lines, timers and other circuits. Microcontroller’s vs. Microprocessors Now a day in electronics usually think that the microcontroller is the same as the microprocessor. That’s not true. They differ from each other in many ways. Microprocessor The microprocessor may be used, other components, memory comes first must be added to it. Even though it is considered a powerful computing machine. It is not adjusted to communicating to peripheral environment. In order to enable the microprocessor to communicate with peripheral environment, special circuits must be used. Microcontroller The first and most important difference in favour of the microcontroller is it is functionality. The microcontroller is designed to be all of that is one. No other specialized external components are needed for its application because all necessary circuits which otherwise belong to peripherals are already built in it its saves time and space needed to design a device. What is 8051 standard? Microcontrollers produces have been struggling for a come time for attracting more and more choosy customers. Every couple of days a new chip with a higher operating frequency more memory and more high quality A/D converters comers on the market. Nevertheless by analyzing their structure it is concluded that most of them have the same architecture known in the product catalogs as “8051 compatible”. The which story began in the far 80’s when Intel launched its series of the microcontrollers labeled with MCS051. Although, several circuits belonging to this series had quite modest features in comparison to the new ones, they took over the world very fast and become a standard for what nowadays is meant by a word microcontroller. That is the reason for having a great number of various microcontrollers which actually are solely upgraded versions of the 8051 family. Central processor unit(CPU) This units which monitors and controls all process within the microcontroller. It consist of several sub units, of which the importance are: Instruction decoder Instruction decoder is a part of electronics which decodes program instructions and runs other circuits on the basics of that. The “instruction set”. Which is different for each microcontrollers family express the abilities of this circuit. Arithmetic logical unit (ALU) ALU performs all mathematical and logical operations upon data. Accumulator Accumulator is an SFR closely related to the operation of the ALU. It’s a kind of working desk used for operation should be performed addition, shift/move, etc. PSW register One of the SFR is called a status register (PSW), is closely related to the accumulator. It shows at any given time “status” of a number stored in the accumulator (number is large or less than zero etc.) Memory unit Memory is part of the microcontroller used for data storage each memory address corresponds to one memory location. Memory can either be written to or read from. Types of memory unit ROM (Read Only Memory) Read only memory is used to permanently save the program being executed. The size of program that can be written depends on the size of this memory. MROM (Masked Read Only Memory) Masked read only memory is a kind of ROM the content of which is programmed by the manufacturer. The term masked comes from the manufacturing process, where regions of the chip are masked off before the process of photolithography. OTPROM (One time programmable ROM) One time programmable ROM enables you to download a program into it, but as its name states one time only. If an error is detected after downloading the only thing you can do is to download the connect program to another chip. UV EPROM (UV Erasable programmable ROM) Both the manufacturing process and characteristics of this memory are completely identical OTP ROM. The package of microcontroller with this memory has a recognizable “window” on its top side. It enables data to be erased under strong ultraviolet light. After a few minutes it is possible to download a new. Flash memory This type memory was invented in the 80’s in the laboratories of INTEL and was represented as the successor to the UV EPROM. Since the content of this memory can be written and cleared practically an unlimited number of times, microcontrollers with flash ROM are ideal for learning experimentation and small-scale production. RAM (Random Access Memory) Once the power supply is off the contents of RAM is cleared. It is used for temporary storing data and intermediate results created and used during the operation of the microcontroller. Interrupt Most programs use interrupts in their regular execution. The purpose of the microcontroller is mainly to respond to changes in its surrounding. The microcontroller delegates the “wait issue” to a “specialist” which will respond only when something attention worthy happens. The signal which informs the central processor unit about such an event is called an interrupt. BUS A bus consists of 8, 16 or more wires. There are two types’ buses: the address bus and the data bus. The address bus consists of as many lines as necessary for memory addressing. It is used to transmit address from the CPU to the memory. The data bus is as wide as the data, in our case it is 8 bits or wires wide. It is used to connect all the circuits within the microcontroller. Serial Communication When it necessary to communication between two devices on longer distances it is not possible to use parallel connection instead serial communication. Today, most microcontrollers have built in several different systems for serial communication as a standard equipment which of these systems will be used depends on many factors of which the most impotent are: How many devices the microcontroller has to exchange data with? How fast the data exchange to be? What is the distance between devices? Is it necessary to send and receive data simultaneously? Power supply circuit There are two thing s worth attention concerning the microcontroller power supply circuit: Brown out Brown out is a potentially dangerous condition which occurs at the moment the microcontroller is being turned off or when the power supply voltage drops to a minimum due to electric noise. As the microcontroller consists of several circuits with different operating voltage levels, this state can because its out of control performance. In order to prevent it, the microcontroller usually has a built in circuit for brown out reset which resets the whole electronics as soon as the microcontroller incurs a state of emergency. Reset pin Reset pin is usually marked as MCLR (master clear reset). It is used for external reset of the microcontroller by applying a logic zero (0) or one (1) to it, which depends on the type of the microcontroller. in case the brown out circuit is no built ina simple external circuit for brown out reset can be connected to the MCLR pin. Oscillator The oscillator is usually configured so as to use quartz crystal or ceramic resonator for frequency stability, but it can also operate as a stand-alone circuit (RC oscillator). It is important to say that instructions are not executed. APPLICATIONS OF MICROCONTROLLER Automotive electronics Embedded system Industrials e- Textiles Aero space Defence Etc……..