Published Book on Amazon
|All of IOT Starting with the Latest Raspberry Pi from Beginner to Advanced – Volume 1|
|All of IOT Starting with the Latest Raspberry Pi from Beginner to Advanced – Volume 2|
출판된 한글판 도서
|최신 라즈베리파이(Raspberry Pi)로 시작하는 사물인터넷(IOT)의 모든 것 – 초보에서 고급까지 (상)|
|최신 라즈베리파이(Raspberry Pi)로 시작하는 사물인터넷(IOT)의 모든 것 – 초보에서 고급까지 (하)|
Original Book Contents
25.8.1 Sensor Overview
A sensor is a device that grasps the state of an object around it and performs a function corresponding to a person's sense. The sensor detects the condition of the object around it, detects the occurrence of the event, senses and measures the variation of the quantity, and delivers it by an electric signal or an optical signal. There are various kinds of sensors such as a light sensor, a temperature sensor, a gas sensor, a pressure sensor, and a magnetic sensor.
Depending on how it works, there are passive sensor (camera, MSS, TM, HRV) which passively accept ambient conditions and active sensor (Radar, Laser) that actively send electromagnetic waves and receive it again.
The sensor is classified into an analog sensor and a digital sensor depending on the type of signal by which it delivers the measured value. The first value measured by a sensor from external environment is the analog type of data. The analog sensor sends this measured value as an analog signal, and the digital sensor converts this measured value into a digital signal and sends the digital signal.
Normally, computers can not process analog signals. Therefore, when an analog sensor is used, it is necessary to convert an analog signal into a digital signal. An ADC (analog-to-digital converter) device converts an analog signal to a digital signal, while a DAC (digital-to-analog converter) device converts a digital signal to an analog signal. Depending on the interface device, the signal conversion device may be provided internally, or it may be installed separately.
Raspberry Pi can not process the analog signal sent by the analog sensor. Therefore, if you want to use an analog sensor, you have to use an additional signal converter or create a separate electronic circuit that converts it separately.