Raspberry Pi_Eng_25.5.7 Sensor

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25.5.7 Sensor

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 an object around it, detects the occurrence of an event, senses and measures a variation of quantity, and delivers it with an electric signal or 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. There are also passive sensors (camera, MSS, TM, HRV) that passively accept the ambient conditions according to the way they operate, and active sensors (Radar, Laser) that send electromagnetic waves and receive it again.

Raspberry Pi_Eng_25.5.6 LED Light

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25.5.6 LED Light

LED (Light-emitting diode) is widely used as a oupput device for determining whether electricity flows through a specific line when constructing an electronic circuit. LED lights up when the voltage is applied, so it can indicate whether the specific GPIO port of the Raspberry Pi is high or low, and can determine if electricity flows on a certain line of the circuit. The GPIO port of Raspberry PI does not provide high power enough to drive high-brightness LED, so buy low-power LED (typical LED) when purchasing LED.

Raspberry Pi_Eng_25.5.5 Push Button

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25.5.5 Push Button

There are many types of buttons used in electronic circuits. Among them, Push-Button is a very simple input device. Pressing the button will connect the circuit, and if the switch is released, the connection is cut off immediately, so it is also called a momentary contact switch.

Raspberry Pi_Eng_25.5.4 Resistor

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25.5.4 Resistor

25.5.4.1 Meaning of Resistor

A resistor is an electronic component that has the effect of dropping voltage by interrupting the flow of current so that the current does not flow well in the electric circuit. It is often used in most electronic circuits. The unit of resistance is ohm (ohm), which is denoted by Ω.

Raspberry Pi_Eng_25.5.3 Jumper Wire

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25.5.3 Jumper Wire

Jump wires are used to connect components and circuits when constructing a circuit. With a breadboard, you can connect electronic components to Raspberry Pi to a certain extent without using wires, but you still need wires to connect rows and rows on the breadboard.

Raspberry Pi_Eng_25.5.2 Breadboard

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25.5.2 Breadboard

25.5.2.1 Structure of Breadboard

The breadboard is a device where the 2.54mm spaced holes to allow wires to be inserted are placed in a lattice pattern on the front so that electronic components can be easily inserted and removed again.

The device below is a typical breadboard. The part where two red and blue lines are drawn vertically on the left and right is called a Bus area. It is usually used by connecting the power source. Connect the (+) power source to the red color and the negative (-) power source to the blue color. In the center, the part where is separated into two parts horizontally and consists of each 5 holes is called an IC (Integrated circuits) area. It is a place where various parts can be arranged. Both sides have small holes, so you can construct the circuit by inserting the legs of various parts.

Raspberry Pi_Eng_25.5.1 GPIO Extension Board

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25.5 Preparations and Usages for Interface

25.5.1 GPIO Extension Board

Raspberry Pi’s GPIO pin is attached to the body of the system board, so it is difficult to connect to the external circuit when you put the board itself in the protective box. Also, as the name of each pin is not marked, you have to check each pin one by one when you are work with it. Also, it is very inconvenient to connect electronic parts or circuits directly to the GPIO pins due to the shape of individual pin or the space constraint between the pins.

Raspberry Pi_Eng_25.4.6 Direct Current Power

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25.4.6 Direct Current Power

The power of electricity is called electric power. The electric power is equal to the value of multiplying a voltage by a current. Electric power means the amount of energy consumed when a current goes through a resistance. The electric power is expressed in W (Watt).

The electric power at direct current is calculated as follows.

Electric Power = Voltage × Current ( P = VI )

Raspberry Pi_Eng_25.4.5 Pull-up Resistor and Pull-down Resistor

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25.4.5 Pull-up Resistor and Pull-down Resistor

In many electronic circuits, it is the pull-up resistor and pull-down resistor that are used as one of the methods to safely protect the circuit from being broken down from various electrical shocks and to ensure that it can operates correctly according to the originally designed intention under any circumstances. Basically, the pull-up resistor and pull-down resistor are a term defined by where to equip the resistor between power supply and ground, and allow a small current to flow by using a resistor of appropriate size for each resistor. Next, we will explain this.

Raspberry Pi_Eng_25.4.4 Kirchhoff’s Laws

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25.4.4 Kirchhoff’s Laws

Kirchhoff’s law has a first law of current and a second law of voltage.

25.4.4.1 First Law – The Law of Current

The first rule is that on a certain path of current, the sum of incoming currents and the sum of outgoing currents is the same. That is, the sum of the current flowing into one point of the circuit and the current flowing out of the point is the same.