2. Components Introduction

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2.1 Raspberry Pi

(a)

A Raspberry Pi is an indispensable component of the kit, the control device. But it is not included in the kit and you need to prepare one yourself.

The Raspberry Pi is a kind of minicomputer for amateurs, teachers, students, and small business users. With a pre-installed Linux system, it is credit card-sized and equipped with an ARM architecture processor, whose operational performances are similar with the smart phones. As for ports, the Raspberry Pi provides USB ports for mouse and keyboard. In addition, there are also ports for the Fast Ethernet, SD card, and HDMI HD video output which can be connected with a display or TV. Being low cost and low consumption, the Raspberry Pi is very suitable for embedded projects. Many people have been able to apply the Pi to a variety of projects including some simple ones for children and complex ones with more advanced functions. You can apply it like a PC for spreadsheets-making, word-processing and games, or to play HD videos of up to 1080p.

It can’t be better describing the Raspberry Pi as “though small, perfectly formed”. It has the same ability compared with the PC and carries ports for the USB, Ethernet, HDMI, RCA, and 3.5mm stereo jack. Moreover, it can control GPIOs while the PC cannot. Through this kit, you will learn how to use the GPIOs to make simple experiments and how to program.

The Raspberry Pi evolves through many versions including the latest (so far) Raspberry Pi 3 Model B, 2 model B, 1 Model B+, Zero, and 1 Model A+. Certainly, the newer, the more powerful. The 3 model B now even comes with Bluetooth and Wi-Fi. You can choose according to actual needs.

Now let’s get to know the components in the kit!

2.2 Jumper Wires

Wires that connect two terminals are called jumper wires. There are various kinds of jumper wires. Here we focus on those used in breadboard. Among others, they are used to transfer electrical signals from anywhere on the breadboard to the input/output pins of a microcontroller.

Jumper wires are fitted by inserting their “end connectors” into the slots provided in the breadboard, beneath whose surface there are a few sets of parallel plates that connect the slots in groups of rows or columns depending on the area. The “end connectors” are inserted into the breadboard, without soldering, in the particular slots that need to be connected in the specific prototype.

There are three types of jumper wire: Female-to-Female, Male-to-Male, and Male-to-Female. The reason we call it Male-to-Female is because it has the outstanding tip in one end as well as a sunk female end. Male-to-Male means both side are male and Female-to-Female means both ends are female. The Male-to-Male jumper wires are included in the kit which you can insert into the breadboard or control board.

(b)

More than one type of them may be used in a project. The color of the jump wires is different but it doesn’t mean their function is different accordingly; it’s just designed so to better identify the connection between each circuit, and also make the whole circuit colorful and better looking.

2.3 Breadboard

A breadboard is a construction base for prototyping of electronics. It is used to build and test circuits quickly before finalizing any circuit design. And it has many holes into which components like ICs and resistors as well as jumper wires mentioned above can be inserted. The breadboard allows you to easily plug in and remove components. So if there are going to be many changes or if you just want to make a circuit quickly, it will be much quicker than soldering up your circuit. Therefore in lots of experiments, it is often used as a hub to connect two or more devices.

Normally, there are two types of breadboard: full+ and half+. You can tell their difference from the names. A half+ breadboard is half the size of a full+ one and their functions are the same. Here take the full+ breadboard.

(c) Full+

(d) Half+

This is the internal structure of a full+ breadboard. Although there are holes on the breadboard, internally some of them are connected with metal strips. Those holes are to insert pins of devices or wires. As shown in the fig. (e) below, there are four long metal strips on the long sides; the blue and red lines are marked just for clear observation. But you can take the blue line as the GND and red one as VCC for convenience. Every five holes in the middle are vertically connected with metal trips internally which don’t connect with each other. You can connect them horizontally with wires or components. A groove is made in the middle on the breadboard for IC chips.

(e) Internal structure of the full+

Now let’s make some simple experiment with the breadboard. Turn on an LED as shown in the figure below. You can have a try and the LED will light up. The breadboard makes it possible for you to plug and pull components at any time without welding, which is very convenient for tests.

(f)

2.4 T-Extension Board & 40-Pin GPIO Cable

(g)

Their function is to lead out pins of the Raspberry Pi to the breadboard in case of GPIO damage caused by frequent plugging in or out. The connection with the Raspberry Pi and breadboard is as follows.

(h)

Thus we can insert pins of other devices into the breadboard for connection to do the experiment. Let’s check out the pins on the T-Extension Board first.

The middle column is the pin names marked on the extension board, and the corresponding pin names are provided on its left and right for numbering by BCM (Python based on )and by wiringPi (C language based on ). The Name column is what the Raspberry Pi defines of the pin (40 pins).

Pins on the T-Extension Board are numbered by the BCM (Broadcom numbering) method. Most of the GPIO pins (on the right half below) are the same with the BCM, except for some special ones which retain their original names such as ID_SCL and ID_SDA.

(i)

You should be pretty familiar with this figure as in the process of writing the code, you need to know which pin the device connects to and which to be defied in the code. For example, if you connect your device to B17, it’s 17 in the BCM column and 0 in wiringPi. There is another naming method for the Raspberry Pi pins: physical, which means numbering based on the physical location of the 40 pin headers as shown below. For more details, please refer to the lessons later.

(j)

2.5 TF Card

(k)

This is an 8GB TF (or microSD) card which functions like the hard disk of a computer, which is indispensable to make a computer work. Similarly, the Raspberry Pi needs a TF card to run. Please refer to the lessons later for the detailed installation. You can also purchase a TF card with larger capacity if necessary.

2.6 AC Power Adapter (5V, 2.5A)

(l)

It is used to supply power for the Raspberry Pi which requires at least 700mA current supply at 5V. The Raspberry Pi cannot work normally if the power is not enough, so make sure the current of the adapter is sufficiently large.

 2.7 Resistor

Resistor is an electronic element that can limit the branch current. A fixed resistor is one whose resistance cannot be changed, when that of a potentiometer or variable resistor can be adjusted.

The resistors in this kit are fixed ones. It is essential in the circuit to protect the connected components. Figure (m) below shows a 220Ω resistor. Ω is the unit of resistance and the larger includes KΩ, MΩ, etc. Their relationship can be shown as follows: 1 MΩ=1000 KΩ,1 KΩ = 1000 Ω, which means 1 MΩ = 1000,000 Ω = 10^6 Ω. Figure (n) and (o) show two generally used circuit symbols for resistor. Normally, the resistance is marked on it. So if you see these symbols in a circuit, it stands for a resistor.

(m)

 (n)

                  (o)                                

The resistance can be marked directly, in color code, and by character. The resistors offered in this kit are marked by different colors. Namely, the bands on the resistor indicate the resistance.

When using a resistor, we need to know its resistance first. Here are two methods: you can observe the bands on the resistor, or use a multimeter to measure the resistance. You are recommended to use the first method as it is more convenient and faster. If you are not sure about the value, use the multimeter.

In the kit, a Resistor Color Code Calculator card is provided as shown below:

(p)

As shown in the card, each color stands for a number.

BlackBrownRedOrangeYellowGreenBlueVioletGreyWhiteGoldSilver
01234567890.10.01

The 4- and 5-band resistors are frequently used, on which there are 4 and 5 chromatic bands. Let’s see how to read the resistance value of a 5-band resistor as shown below. Normally, when you get a resistor, you may find it hard to decide which end to start for reading the color. The tip is that the gap between the 4th and 5th band will be comparatively larger. Therefore, you can observe the gap between the two chromatic bands at one end of the resistor; if it’s larger than any other band gaps, then you can read from the opposite side. 

(q)

So for this resistor, the resistance should be read from left to right. The value should be in this format: 1st Band 2nd Band 3rd Band x 10^Multiplier (Ω) and the permissible error is ±Tolerance%. So the resistance value of this resistor is 2(red) 2(red) 0(black) x 10^0(black) Ω = 220 Ω, and the permissible error is ± 1% (brown).

One more example. The resistance of the resistor below should be 1(brown)  0(black)  0(black) x 10^1(brown) Ω =100×10 Ω = 1000 Ω = 1KΩ, and the permissible error is ± 1%(brown). Now try it by yourself!

(r)

2.8 LED

Semiconductor light-emitting diode is a type of component which can turn electric energy into light energy via PN junctions. By wavelength, it can be categorized into laser diode, infrared light-emitting diode and visible light-emitting diode which is usually known as light-emitting diode (LED).

                  (s)          

          (t)

See LED in figure (k). Figure (l) is the circuit symbol. Diode has unidirectional conductivity, so the current flow will be as the arrow indicates in figure (l). You can only provide the anode with a positive power and the cathode with a negative. Thus the LED will light up.

In this kit, LEDs of red, green, and yellow are provided. An LED has two pins. The longer one is the anode, and shorter one, the cathode. Pay attention not to connect them inversely. There is fixed forward voltage drop in the LED, so it cannot be connected with the circuit directly because the supply voltage can outweigh this drop and cause the LED to be burnt. The forward voltage of the red, yellow, and green LED is 1.8 V and that of the white one is 2.6 V. Most LEDs can withstand a maximum current of 20 mA, so we need to connect a current limiting resistor in series.                  

The formula of the resistance value is as follows:

R = (Vsupply – VD)/I

R stands for the resistance value of the current limiting resistor, Vsupply for voltage supply, VD for voltage drop and I for the working current of the LED.

If we provide 5V for the red LED, the minimum resistance of the current limiting resistor should be: (5V-1.8v)/20mA = 160Ω. Therefore, you need a 160Ω or larger resistor to protect the LED. You are recommended to use the 220Ω resistor offered in the kit.

2.9 RAB Holder

When using the Raspberry Pi, DO NOT put the bare board onto a conductive surface such as a table with a metal surface in case the soldering pins on the back of the board may touch the conductor and thus generate a short circuit and damage the board. Sometimes you may overlook the metal end of a wire under the Raspberry Pi, which connects to its pin and leads to a short circuit. So it’s suggested to install the board onto the RAB Holder to avoid possible short circuits on the back.

The three hollows of the RAB Holder are designed for a Raspberry Pi, Arduino Mega2560/Uno, and breadboard respectively. If you want to use the three together, the RAB Holder can play a great role in fixing, making it a quite useful and significant component in experiments.

(x)

2.10 Case

This is an elegant and innovative protective case designed specifically for the Raspberry Pi. This two-piece injection-molded ABS enclosure incorporates snap-fit mounting points that hold the Pi securely in place. It also provides the best available protection/accessibility for the Raspberry Pi.