An Introduction To Microcontrollers Information Technology Essay

A universal cheap integrated circuit which can be programmed and used in many fields of electronics, devices or wherever needed for, technology has been developed enough as well as the market.

A microcontroller (mentioned as µC, uC or MCU) is a single integrated circuit consists of a processor core, memory, and programmable input/output terminals works as a mini computer. 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. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications.

Microcontrollers are used mostly in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes. Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems.

Some microcontrollers may use four-bit words and operate at clock rate frequencies as low as 4 kHz, for low power consumption (mill watts or microwatts). They will generally have the ability to retain functionality while waiting for an event such as a button press or other interrupt; power consumption while sleeping (CPU clock and most peripherals off) may be just nanowatts, making many of them well suited for long lasting battery applications. Other microcontrollers may serve performance-critical roles, where they may need to act more like a digital signal processor (DSP), with higher clock speeds and power consumption.

What is the microcontroller and what are they used for?

Like all good things, this powerful component is basically very simple. It is made by mixing tested and high- quality “ingredients” (components) as per following receipt:

The simplest computer processor is used as the “brain” of the future system.

Depending on the taste of the manufacturer, a bit of memory, a few A/D converters, timers, input/output lines etc. are added

All that is placed in some of the standard packages.

Simple software able to control it all and which everyone can easily learn about has been developed.

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On the basis of these rules, numerous types of microcontrollers were designed and they quickly became man’s invisible companion. Their incredible simplicity and flexibility conquered us a long time ago.

The following things have had a crucial influence on development and success of the microcontrollers:

Powerful and carefully chosen electronics embedded in the microcontrollers can independently or via input/output devices (switches, push buttons, sensors, LCD displays, relays etc.), control various processes and devices such as industrial automation, electric current, temperature, engine performance etc.

Very low prices enable them to be embedded in such devices in which, until recent time it was not worthwhile to embed anything. Thanks to that, the world is overwhelmed today with cheap automatic devices and various “smart” appliances.

Prior knowledge is hardly needed for programming. It is sufficient to have a PC (software in use is not demanding at all and is easy to learn) and a simple device (called the programmer) used for “loading” ready-to-use programs into the microcontroller.

So, if you are infected with a virus called electronics, there is nothing left for you to do but to learn how to use and control its power.

How does the microcontroller operate?

Even though there is a large number of different types of microcontrollers and even more programs created for their use only, all of them have many things in common. Thus, if you learn to handle one of them you will be able to handle them all. A typical scenario on the basis of which it all functions is as follows:

Power supply is turned off and everything is still…the program is loaded into the microcontroller, nothing indicates what is about to come…

Power supply is turned on and everything starts to happen at high speed! The control logic unit keeps everything under control. It disables all other circuits except quartz crystal to operate. While the preparations are in progress, the first milliseconds go by.

Power supply voltage reaches its maximum and oscillator frequency becomes stable. SFRs are being filled with bits reflecting the state of all circuits within the microcontroller. All pins are configured as inputs. The overall electronis starts operation in rhythm with pulse sequence. From now on the time is measured in micro and nanoseconds.

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Program Counter is set to zero. Instruction from that address is sent to instruction decoder which recognizes it, after which it is executed with immediate effect.

The value of the Program Counter is incremented by 1 and the whole process is repeated…several million times per second.

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What is inside the microcontroller?

All the operations within the microcontroller are performed at high speed and quite simply, but the microcontroller itself would not be so useful if there are not special circuits which make it complete. In continuation, we are going to call your attention to them.

Read Only Memory (ROM):

Read Only Memory (ROM) is a type of memory used to permanently save the program being executed. The size of the program that can be written depends on the size of this memory.

Random Access Memory (RAM):

Random Access Memory (RAM) is a type of memory used for temporary storing data and intermediate results created and used during the operation of the microcontrollers.

Electrically Erasable Programmable ROM (EEPROM):

The EEPROM is a special type of memory not contained in all microcontrollers. Its contents may be changed during program execution (similar to RAM), but remains permanently saved even after the loss of power (similar to ROM).

Special Function Registers (SFR):

Special function registers are part of RAM memory. Their purpose is predefined by the manufacturer and cannot be changed therefore. Since their bits are physically connected to particular circuits within the microcontroller, such as A/D converter, serial communication module etc., any change of their state directly affects the operation of the microcontroller or some of the circuits.

Program Counter:

Program Counter is an engine running the program and points to the memory address containing the next instruction to execute.

Central Processor Unit (CPU):

As its name suggests, this is a unit which monitors and controls all processes within the microcontroller and the user cannot affect its work.

Input/output ports (I/O Ports):

In order to make the microcontroller useful, it is necessary to connect it to peripheral devices. Each microcontroller has one or more registers (called a port) connected to the microcontroller pins.

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Oscillator:

Even pulses generated by the oscillator enable harmonic and synchronous operation of all circuits within the microcontroller. It is usually configured as to use quartz-crystal or ceramics resonator for frequency stabilization.

Timers/Counters:

Most programs use these miniature electronic “stopwatches” in their operation. These are commonly 8- or 16-bit SFRs the contents of which are automatically incremented by each coming pulse.

Watchdog timer:

The Watchdog Timer is a timer connected to a completely separate RC oscillator within the microcontroller.

If the watchdog timer is enabled, every time it counts up to the program end, the microcontroller reset occurs and program execution starts from the first instruction. The point is to prevent this from happening by using a special command.

Power Supply Circuit:

There are two things worth attention concerning the microcontroller power supply circuit:

Brown out is a potentially dangerous state which occurs at the moment the microcontroller is being turned off or when power supply voltage drops to the lowest level due to electric noise.

Reset pin is usually referred to as Master Clear Reset (MCLR) and serves for external reset of the microcontroller by applying logic zero (0) or one (1) depending on the type of the microcontroller.

Wireless sensor network

By Microcontrollers

We will present you in this project a wireless sensor network made by Microcontrollers, Sensors, Infrared Transmitters and Receivers, LCD, Power Suppliers and Analog to Digital Converters.

By spreading four nodes within a certain room and using Infrared to connect them which is more recommended for human health rather than the Radio Frequency signals.

Each node of the three slaves has a role of measuring the temperature through the sensors in its certain area and one by one transmitting the measures to the Master unit which do its operation using the Microcontrollers inside it to get the average temperature between the four nodes, the timing organization of operations of transmitting and receiving the IR signals in between the nodes is also made by the Microcontrollers.

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