IoT Week 4 Lecture Notes PDF

Istanbul Beykent University INTERNET OF THINGS DEPARTMENT OF COMPUTER ENGINEERING 1 IoT Communication APIs The application program (or programming) interface, or API, is arguably what really ties toge...

Istanbul Beykent University INTERNET OF THINGS DEPARTMENT OF COMPUTER ENGINEERING 1 IoT Communication APIs The application program (or programming) interface, or API, is arguably what really ties together the connected “things” of the “internet of things.” IoT APIs are the points of interaction between an IoT device and the internet and/or other elements within the network These are Two Types 1. REST based communication APIs (Request-Response Based Model) 2. Web Socket based Communication APIs (Exclusive Pair Based Model) 2 REST based communication APIs REST based communication APIs: Representational State Transfer(REST) is a set of architectural principles by which we can design web services and web APIs that focus on a system‘s resources and have resource states are addressed and transferred. 3 Request-Response model used by REST 4 Web Socket based Communication APIs WebSocket APIs allow bi-directional, full duplex communication between clients and servers. WebSocket APIs follow the exclusive pair communication model. 5 Web Socket based Communication APIs 6  Sensing Sensor: “A device which detects or measures a physical quantity and converts its into a equivalent electrical signal” 7 Example Heat is converted to electrical signals in a temperature sensor. Atmospheric pressure is converted to electrical signals in a barometer 8 Transducers  Transducers convert or transduce energy of one kind into another.  For example, in a sound system, a microphone (input device) converts sound waves into electrical signals for an amplifier to amplify (a process), and a loudspeaker (output device) converts these electrical signals back into sound waves. 9 Sensor Features It is only sensitive to the measured property (e.g., A temperature sensor senses the ambient temperature of a room.) It is insensitive to any other property likely to be encountered in its application (e.g., A temperature sensor does not bother about light or pressure while sensing the temperature.) It does not influence the measured property (e.g., measuring the temperature does not reduce or increase the temperature). 10 Sensor Resolution The resolution of a sensor is the smallest change it can detect in the quantity that it is measuring. The resolution of a sensor with a digital output is usually the smallest resolution the digital output it is capable of processing. The more is the resolution of a sensor, the more accurate is its precision. A sensor’s accuracy does not depend upon its resolution. 11 Sensor Based on Energy Passive and Active Classes Sensors Based on Output Analog and Digital Sensors Based on Data type Scalar and Vector Sensors 12 Passive Sensor A Passive sensor is a sensing device that simply detect and respond to some type of input from the physical environment. Example: Metal Detector, A Light Dependent Resistor (LDR) 13 Active Sensor An active sensor is a sensing device that requires an external source of power to operate. Example: radar, GPS, x- ray, sonar, infrared. 14 Analog Sensors  Analog Sensors produce a continuous output signal or voltage which is generally proportional to the quantity being measured.  Physical quantities such as Temperature, Speed, Pressure, Displacement, Strain etc. are all analog quantities as they tend to be continuous in nature. For example, the temperature of a liquid can be measured using a thermometer or thermocouple (e.g. in geysers) which continuously responds to temperature changes as the liquid is heated up or cooled down. 15 Digital Sensors  Digital Sensors produce discrete digital output signals or voltages that are a digital representation of the quantity being measured.  Digital sensors produce a binary output signal in the form of a logic “1” or a logic “0”, (“ON” or “OFF”). Digital signal only produces discrete (non‐continuous) values, which may be output as a single “bit” (serial transmission), or by combining the bits to produce a single “byte” output (parallel transmission). 16 Scalar Sensors  Scalar Sensors produce output signal or voltage which is generally proportional to the magnitude of the quantity being measured.  Physical quantities such as temperature, color, pressure, strain, etc. are all scalar quantities as only their magnitude is sufficient to convey an information. For example, the temperature of a room can be measured using a thermometer or thermocouple, which responds to temperature changes irrespective of the orientation of the sensor or its direction. 17 Vector Sensors  Vector Sensors produce output signal or voltage which is generally proportional to the magnitude, direction, as well as the orientation of the quantity being measured.  Physical quantities such as sound, image, velocity, acceleration, orientation, etc. are all vector quantities, as only their magnitude is not sufficient to convey the complete information.  For example, the acceleration of a body can be measured using an accelerometer, which gives the components of acceleration of the body with respect to the x,y,z coordinate axes. 18 Sensor Types Temperature Sensor Ultrasonic Sensor Proximity Sensor Image sensors Pressure Sensor Motion Detection Sensors Water Quality Sensor Accelerometer Sensors Chemical/Smoke & Gas Sensor Gyrometer Sensors Level Sensor Humidity Sensors IR Sensor Optical Sensors 19  B A SI S F OR SE N SOR TRA N SDUCE R COM PA R I SON Sensor vs Definition Senses the physical The transducer is a changes occurs in device which, when the surrounding and actuates transforms converting it into a the energy from one readable quantity. form to another. Transduce Components Sensor itself Sensor and signal conditioning r Function Detects the changes and induces the corresponding electrical signals. Conversion of one form of energy into another. Examples Proximity sensor, Thermistor, Magnetic sensor, Potentiometer, Accelerometer Thermocouple, etc. sensor, Light sensor etc. 20