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Modern Measuring &

Display SystemsArsl an Anju m

2010-MM-14


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1MODERN MEASURING AND DISPLAY SYSTEMS

Microcontrollers

Microcontroller is an integrated chip/circuit containing many of the same items that a computer

has, such as CPU, memory etc. but does not include any human interaction devices like keyboard

or mouse. These devices are very small and used as controller because they control machines,

gadgets etc. By definition micro-controller are used to connect machines rather than to humans.

We can surely build an instrument, feed the program in it and allow it to control it automatically.

Microcontrollers are very versatile i.e. the same device can be used in engine or in a toaster or

even in the microwave oven.

Generally there are two types of microcontroller.

Single Programmable ReProgrammable

Single programmable instruments are once programmed and used for specified applications

like our cars antilock braking system.

ReProgrammable instruments are used over and over for multiapplications.

These instruments can use 4-bit words and can function at the frequencies of clock rate like 4

kHz. They have the ability to retain their performance during the button press or other such

interference. Their power consumption may be nanowatts, so they can be used in long lasting

applications.

History

In 1869, some Japanese engineers had gone to USA with a proposal that they need few

integrated devices for calculation in their project. Their request was forwarded to INTEL, and

here came the idea that with a single type of integrated circuit, a greater memory and

functionality can be achieved.

Microcontroller Description

A microcontroller having a little memory, ram and speed can be used for small calculations. A

simple microcontroller has three parts A, B & C. We can install or feed the program according to

our requirement. Quartz Crystal oscillator is used as processor in some microcontroller. The

material constant is 0.051mV/ .


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A microcontroller cannot detect mV; to detect this Analogue to Digital Converter (ADC) is

attached to it. So microcontroller converts the analogue signal into the digital signal. ADC has 8

bit minimum resolution. 10, 16 and 12 bit are also common.

Like a computer, a microcontroller should have input pins to connect to the system and output

pins to display the results of the system affecting on it.

ADC(analogue to digital converter)

Microcontrollers are devices that read the inputs, do processing and write to outputs (control).

Microcontroller can detect the parameters for it is used; it is the ADC that is used to convert the

value in a suitable recognized value. In ADC binary system is used. Here an 8 bit ADC is shown

for voltage control. It is operated at 5mV and divided according to its resolution. When there is

4.88mV then it displays 1 and it displays 0 when less than 4.88. At 4.882 = 9.76 it displays 2

and so on. We can make the microcontroller to carry on decision at different voltage value.

0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 1

2 0 0 0 0 0 0 1 0

3 0 0 0 0 0 0 1 1

4 0 0 0 0 0 1 0 0

5 0 0 0 0 0 1 0 16 0 0 0 0 0 1 1 0

7 0 0 0 0 0 1 1 1


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Di ff erent M icrocontrollers

Here are some of the types of microcontrollers along with their specifications.

Type Program

memory (KB)

Ram (bytes) ADC Temperature

Range ()

Voltage

Range(V)

16f676 1.75 64 10 bit -40 to 125 25.5

16f677 3.5 128 10 bit Do 2 to 5.5

16f685 7 256 12 ch, 10 bit Do do

16f707 14 368 14 ch, 8 bit Do 1.8 to 5.5

16f767 28 1024 11 ch, 10 bit Do Do

Applications

With the increasing of measuring capability and electrical complexity, microcontrollersare used in automobiles industries like in fuel indication system etc.

These are also used in telecommunication to reduce complexity, weight, cost andinterconnections.

They are also used in different machines to indicate the safe values and limits for

running of smooth process.

They find their applications in satellites and rockets to indicate the pressure value of air,position and level of liquids.

Display Systems

There are two types of display systems mainly concerned.

7 segment displays

Alpha numeric

7 Segment Display

This system of displays is used anywhere we need a visual description of the measured

quantities. We can display all digits 0-9 through this type of display system. In displaying three

digits we need 21 LEDs and 42 wires are used to control it. To compensate it we reduce the


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wires, one for the negative junction and 7 for the positive junction. So total 8 wires are combined

to display a digit. This implies that 24 wires are used for 3-digit display.

Alpha Numeri c Display

This type of display is playing an important role in the field of electronics. It not only

displays the values of the quantities, but also displays the precautions, the name of the quantity to

be measured and the some information regarding the experiment. Generally we can display the

digits and the alphabets simultaneously.

This type of display is used in word processors, palmtop computers, photocopiers and medical

instruments. The 162 alphanumeric dot matrix has the ability to display 224 characters orsymbols. In this system every dot of the display is controlled. It is connected to a single

microcontroller pin and it enables the controller to visualize the readings and the instructions on

the LCD module.

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