Internet of Things and its Applications

Sensors, Actuators and Microcontrollers Question & Answer

Question : 1

Write short notes on the following:

(a) Microcontrollers
(b) Microprocessors
(c) DC Motors
(d) Embedded System
(e) Sensor

Answer :

Microcontrollers (embedded processors) are processors (or specialized microprocessors) that have many peripherals to interact with real-word sensors and actuators. Microcontrollers are typically employed in scenarios that must have low power consumption, operate fan-less, thus must have low power dissipation Also, often micro-controllers run relatively simpler set of instructions.
Microprocessors (Application processors) usually are for general-purpose applications, and rarely have many peripheral interconnect options. They target high performance applications, focus on computational power, and thus come with multiple level of caches, have very high clock speeds, have less to worry about power dissipation and power consumption. Often, they have little or no onboard RAM.
DC motors, which move at variable speeds. In DC motors, the coil of wire (rotor) assembly rotates in an attempt to align itself with the stator assembly but is prevented by a part known as the commutator. At the precise moment, the commutator switches the rotor field while the stator assembly remains stationary. This provides the means to control speed and positioning.
An embedded system can be thought of as a computer hardware system having software embedded in it. An embedded system can be an independent system or it can be a part of a large system. An embedded system is a microcontroller or microprocessor based system which is designed to perform a specific task. For example, a fine alarm is an embedded system; it will sense only smoke.
The sensor can be defined as a device which can be used to sense / detect the physical quantity like force, pressure, strain, light etc and then convert it into desired output like the electrical signal to measure the applied physical quantity.

Question : 2

Write short note on Thermistor.

Answer :

A thermistor can be used to detect the variation in temperature. It has a negative temperature coefficient that means when the temperature increases the resistance decreases. So, the thermistor's resistance can be varied with the rise in temperature which causes more current flow through it. This change in current flow can be used to determine the amount of change in temperature. An application for thermistor is, it is used to detect the rise in temperature and control the leakage current in a transistor circuit which helps in maintaining its stability. Thermistor is used to control the DC fan automatically.

Question : 3

Difference between Microprocessor and Microcontroller are:

Answer :

Difference between Microprocessor and Microcontroller are:

Microprocessor widely used in the computer system. And microcontroller is used in embedded system.
Microprocessor is used in Personal Computers whereas Micro Controller is used in an embedded system.
The microprocessor uses Von Neumann architecture where data and program present in the same memory module. The microcontroller uses Harvard architecture. In this module. Data and program get stored in separate memory.
Microprocessor requires external components to operate. So, the Cost of the microprocessor is higher than the microcontroller.
Microprocessor consists of only a Central Processing Unit, whereas Micro Controller contains a CPU, Memory, I / O all integrated into one chip.
Microprocessor uses an external bus to interface to RAM, ROM, and other peripherals, on the other hand, Microcontroller uses an internal controlling bus.
Microprocessor is complicated and expensive, with a large number of instruction to process but Microcontroller is inexpensive and straightforward with fewer instructions to process.

Question : 4

What are the application areas of Microprocessors?

Answer :

Microprocessors are mainly used of devices like:

Calculators
Accounting system
Games machine
Military applications
Computation systems

Question : 5

What are the application areas of Microcontroller?

Answer :

Microcontrollers are mainly used in devices like:

Mobile phones
Automobiles
CD / DVD players
Washing machines
Security alarms
Microwave oven
Mp3 players
Cameras

Question : 6

Differentiate between 8051 and AVR Controllers.

Answer :

Differentiate between 8051 and AVR controllers are:

8051s are 8-bit controllers based on CISC architecture, AVRs are 8-bit controllers based on RISC architecture.
8051 consumes more power than AVR microcontroller.
In 8051, we can program easily than the AVR microcontroller.
The speed of AVR is more than the 8051 microcontroller.

Question : 7

What is transducer?

Answer :

Any device converting signals of one kind to signals of a different kind is a transducer i.e., a transducer is a device which converts one physical quantity to another from of physical quantity, e.g., acceleration to voltage or voltage to pressure.

Question : 8

What is sensor?

Answer :

A sensor is a device that is used to detect changes in any physical quantity like temperature, speed, flow, level, pressure, etc. Any changes in the input quantity will be detected by a sensor and reflected as changes in output quantity.

Question : 9

"A transducer is more general than a sensor." Comment.

Answer :

A sensor is a device which can quantitatively measure a certain physical quantity. A transducer is a device which converts one physical quantity to another from of physical quantity, e.g., acceleration to voltage or voltage to pressure. Therefore, a transducer can be a sensor when it is used to measure a certain physical quantity. But the transducer can also be an actuator when the (electrical) input is converted to, for example, force. So a transducer is more general than a sensor.

Question : 10

Explain Sensor and Actuators with example.

Answer :

Sensor are devices that responds to a physical quantity with a signal and Actuators are devices that respond to signals with physical movement (or similar action) can be considered as transducers.
For example, a Microphone is a Sensor, which converts sound waves into electrical signals and a Loudspeaker is an Actuator, which converts electrical signal into audio signals.

Question : 11

Write short note on Thermocouple.

Answer :

Thermocouple is a temperature sensor that can detect the variation in temperature. In its construction, two different metals are joined construction, two different metals are joined together to form a junction. Its main principle is when the junction. Of two different metals are heated or exposed to high temperatures a potential across their terminals varies. So, the varying potential can be further used to measure the amount of change in temperature.

Question : 12

Discuss important features of a RISC microprocessor.

Answer :

RISC (Reduced Instruction Set Computer)

RISC architecture was developed by realizing that instead of using full set of instructions, only the frequently used instructions are sufficient.
In this architecture, the instructions are small and highly optimized.
RISC processors are used where execution time of the instruction should be less and cost of development is less.
The ARM devices are based on ARM architecture which is a subset of RISC.

Question : 13

Discuss important features of a CISC microprocessor.

Answer :

CISC architecture consists of full set of instructions that are complex, larger, have more computational power and so on.
A single CISC instruction can be used to execute several low-level operations, multistep operations and multiple addressing modes.
The execution time of these instructions is long. Intel's X86 is an example of CISC architecture.

Question : 14

Write properties of EPIC processor.

Answer :

EPIC (Explicitly Parallel Instruction Computing) is a computer architecture that combines the best feature of RISC and CISC.
A EPIC processor has the following properties:

EPIC does not use fixed with instruction, rather aims at parallel processing of instructions.

Programs must be written using sequential semantics with explicitly laid out parallelism.

It uses a bundle of complex instructions that in addition to basic instruction also contain information on how to run the instruction in parallel with other instructions.

Question : 15

What are Advantages and Disadvantages of Microcontroller?

Answer :

Lower cost because many elements of the processor are contained within the one chip resulting in lower chip cost.
Lower power consumption.
Integrating all consumption onto one chip enables processor to be optimised for a given application.
Disadvantages of Microcontroller are:
Less flexibility because all components are integrated into the one chip.
Limited performance because the size of memory is limited by what can be accommodated on the chip.
MCUs tend to be application specific so the choice may be limited.

Question : 16

How does Microprocessor work?

Answer :

There are five important components in a microprocessor. They are Arithmetic and Logic Unit (ALU), Control Unit, Registers, Instruction Decoder and Bus. Microprocessor holds the number of instruction. Every instruction consists of multiple steps such as fetch, decode, executes and store. While running instruction in the microprocessor, it executes multiple steps as Fetch the input, Decode instruction, Execute instruction, Store result back in the memory. Here, Instruction gets fetched and input is given externally using I / O components. The microprocessor executes an instruction. The result gets stored in the externally connected memory unit.

Question : 17

What are the criteria for choosing a microcontroller are?

Answer :

Criteria for choosing a microcontroller are:

The first and foremost criterion in choosing a microcontroller is that it must meet the task at hand efficiently and cost effectively.
In analyzing the needs of a microcontroller based project, we must first see whether an 8-bit, 16-bit, or 32-bit microcontroller can best handle the computing needs of the task most effectively.
Power consumption especially critical for battery-powered products.
The amount of RAM and ROM on chip.
The number of I/O pins and the timer on the chip.
The highest speed that the microcontroller supports.

Question : 18

Write some application areas of AVR Microcontroller.

Answer :

Application areas of AVR Microcontroller are:

Robotics and Embedded systems
Bio-medical equipment
Automobiles and security system
Temperature, light sensing and Fire detection devices
Industrial automation devices

Question : 19

How Active sensors is different from Passive sensors?

Answer :

Active sensors are those which require an external excitation signal or a power signal. Passive sensors, on the other hand, do not require any external power signal and directly generates output response.

Question : 20

Explain Passive Transducers with example.

Answer :

In Passive Transducers, the energy from the input is directly converted into the output. For example, a Thermocouple is a passive transducer, where the heat energy, which is absorbed from input, is converted into electrical signal (voltage).

Question : 21

Define computer architecture.

Answer :

Computer architecture is defined as the functional operation of the individual hardware unit in a computer system and the flow of information among the control of units.