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Learn JavaScript with Raspberry Pi — The MagPi magazine

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Beginner’s Guide to Installing Nodejs on a Raspberry Pi

NodeSchool

Nodejs in Action (2nd Edition)

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Node.js and Raspberry Pi

Node.js and Raspberry Pi

Raspberry Pi is a small, multi-use computer.

With Node.js you can do amazing things with your Raspberry Pi.

What is the Raspberry Pi?

The Raspberry Pi is a small, affordable, and amazingly capable, credit card size computer.

It is developed by the Raspberry Pi Foundation, and it might be the most versatile tech ever created.

Creator Eben Upton’s goal was to create a low-cost device that would improve programming skills and hardware understanding.

Due to the small size and price of the device, it has become the center of a wide range of projects by tinkerers, makers, and electronics enthusiasts.

Raspberry Pi and Node.js

The Raspberry Pi has a row of GPIO (General Purpose input/output) pins, and these can be used to interact in amazing ways with the real world. This tutorial will focus on how to use these with Node.js.

What Do I Need?

For this tutorial you need a Raspberry Pi. In our examples we use a Raspberry Pi 3, but this tutorial should work for most versions.

Hardware needed:

Raspberry Pi computer

MicroSD memory card (We recommend a class 10 with 16 GB or higher)

MicroSD to SD memory card adapter (usually included with the MicroSD card)

Micro USB power supply to power the Raspberry Pi (2.5A or greater recommended)

WiFi/Ethernet Cable connection for the Raspberry Pi (Not needed for Raspberry Pi 3 as it has built in WiFi)

A working computer with internet and SD memory card reader (used to get the OS (Operating System) for the Raspberry Pi onto the memory card). In our tutorial we use a Windows computer for this, but you can use a Mac or Linux computer if you prefer

HDMI monitor, USB keyboard (we need these only temporarily for the first boot of the Raspberry Pi)

For later chapters in this tutorial we will use special sensors or devices that we connect to the Raspberry Pi. We will specify these as special requirements in the relevant chapters.

If you already have a Raspberry Pi set up with Raspbian, internet and enabled SSH, you can skip to the step “Install Node.js on Raspberry Pi”.

Write Raspbian OS Image to MicroSD Card

Before we can start using our Raspberry Pi for anything, we need to get a OS installed.

Raspbian is a free operating system based on Debian Linux, and it is optimized Raspberry Pi.

Download the latest Raspbian image from https://www.raspberrypi.org/downloads/raspbian/ to your computer.

We use the “LITE” version in our tutorial, since we are setting the Raspberry Pi up as a headless server (we will connect to it through SSH, without having a keyboard/display connected to it). You can use whichever version you want, but this tutorial is written with the “LITE” version as its focus.

Insert the MicroSD memory card in your computer (via the SD adapter if needed). Open File Explorer to verify that it is operational.

Etcher is a program for flashing images to memory cards. Download and install Etcher from: https://etcher.io/

Launch Etcher:

Click “Select image” button and find the Raspbian zip file that you downloaded.

Click the “Select drive” button and specify the memory card as the target location.

Click the “Flash!” button to write the image to the memory card.

After Etcher is finished writing the image to the memory card, remove it from your computer.

Set up Your Raspberry Pi

To get the Raspberry Pi ready to boot we need to:

Insert the MicroSD memory card into the Raspberry Pi Connect the USB keyboard Connect the HDMI cable Connect the USB Wi-Fi adapter (or Ethernet cable). Skip this step if you are using a Raspberry Pi 3 Connect the micro USB power supply The Raspberry Pi should now be booting up

When the Raspberry Pi is finished booting up, log in using username: pi and password: raspberry

Set Up Network on the Raspberry Pi

If you will use a Ethernet cable to connect your Raspberry Pi to the internet, you can skip this step.

For this section we will assume you have a Raspberry Pi 3, with built in WiFi.

Start by scanning for wireless networks:

[email protected]:~ $ sudo iwlist wlan0 scan

This will list all of the available WiFi networks. (It also confirms that your WiFi is working)

Now we need to open the wpa-supplicant file, to add the network you want to connect to:

[email protected]:~ $ sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

This will open the file in the Nano editor. Add the following to the bottom of the file (change wifiName and wifiPassword with the actual network name and password):

network={

ssid=”wifiName”

psk=”wifiPassword”

}

Press ” Ctrl+x ” to save the code. Confirm with ” y “, and confirm the name with ” Enter “.

And reboot the Raspberry Pi:

[email protected]:~ $ sudo reboot

After reboot, log in again, and confirm that the WiFi is connected and working:

[email protected]:~ $ ifconfig wlan0

If the WiFi is working propery, the information displayed should include an IP address, similar to this:

inet addr:192.168.1.50

Write down that IP address, as we will use it to connect to the Raspberry Pi via SSH.

Enable SSH, Change Hostname and Password

Now your Raspberry Pi is connected to the internet, it is time to enable SSH.

SSH allows you up use the Raspberry Pi without having a monitor and keyboard connected to it.

(You will need a SSH client for this on your non-Raspberry Pi computer. We use PuTTY for windows)

Open the Raspberry Pi Software Configuration Tool:

[email protected]:~ $ sudo raspi-config

You should see a menu like this:

Select option 5 Interfacing Options :

Select option P2 SSH , to activate SSH:

Confirm with YES , to activate SSH:

SSH is now enabled, and you should be in the main menu again.

Select 1 Change User Password , and follow the instructions to change the password. Choose a secure password, but something you will remember:

After you have finished changing the password, you should be back in the main menu.

Select 2 Hostname , and follow the instructions to change the hostname:

After you have finished changing the hostname, you should be back in the main menu.

Now we will close the menu and save the changes:

When selecting Finish , you will get the option to reboot. Select Yes to reboot the Raspberry Pi.

You can now unplug the monitor and keyboard from the Raspberry Pi, and we can log in using out SSH client.

Open PuTTY, type in the IP address for your Raspberry Pi, and click Open :

Log in using the username pi and the new password you specified.

You should now see a command line like this: (we used w3demopi as our hostname)

[email protected]:~ $

You are now able to run your Raspberry Pi in “Headless-mode”, meaning you do not need a monitor or keyboard. And if you have a WiFi connection, you do not need a ethernet cable either, just the power cable!

Install Node.js on Raspberry Pi

With the Raspberry Pi properly set up, login in via SSH, and update your Raspberry Pi system packages to their latest versions.

Update your system package list:

[email protected]:~ $ sudo apt-get update

Upgrade all your installed packages to their latest version:

[email protected]:~ $ sudo apt-get dist-upgrade

Doing this regularly will keep your Raspberry Pi installation up to date.

To download and install newest version of Node.js, use the following command:

[email protected]:~ $ curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash –

Now install it by running:

[email protected]:~ $ sudo apt-get install -y nodejs

Check that the installation was successful, and the version number of Node.js with:

[email protected]:~ $ node -v

Get Started with Raspberry Pi and Node.js

Now you have a Raspberry Pi with Node.js installed!

If you want to learn more about Node.js, follow our tutorial: https://www.w3schools.com/nodejs/

In the next chapter we will get to know the GPIO and how to use it with Node.js.

Node.js를 이용하여 Raspberry Pi 3에 연결된 LED 제어하기

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웹용 언어인줄로만 알았던 자바스크립트인데 하드웨어 제어도 됩니다. 참 신기합니다.

어떤 장점이 있어서 사용하게 되었는지도 궁금하구요..

찾아보면 Node.js나 비슷한 류를 기반으로 하는 임베디드 보드들도 꽤 있습니다..

2015.11.27

2109. 08.12 – node 설치 방법 변경

문제없이 동작하는 Node.js 버전이 정해져 있어서 해당 버전을 사용해야 합니다.

onoff 깃허브 페이지에서 확인 가능합니다. 주소는 참고 [2]에 있습니다.

다음과 같은 방법을 Node.js 4.8.4를 설치해줍니다.

$ sudo npm cache clean -f

$ sudo npm install -g n

$ sudo n 4.8.4

문제 없으면 다음처럼 버전으로 4.8.4가 출력됩니다.

$ node -v v4.8.4

이제 LED를 제어해보기 위해서 디렉토리를 생성하고 이동해서

$ mkdir ledBlink && cd ledBlink

하드웨어 제어를 위해 사용할 onoff 노드 모듈을 설치합니다.

$ npm install onoff

nano 편집기로 새로운 파일을 하나를 열어서

nano led.js

다음 코드를 복사하여 붙여넣기합니다.

‘use strict’;

const Gpio = require(‘onoff’).Gpio; // Gpio class

const led = new Gpio(21, ‘out’); // Export GPIO17 as an output

// Toggle the state of the LED connected to GPIO17 every 200ms

const iv = setInterval(_ => led.writeSync(led.readSync() ^ 1), 200);

// Stop blinking the LED after 5 seconds

setTimeout(_ => {

clearInterval(iv); // Stop blinking

led.unexport(); // Unexport GPIO and free resources

}, 5000);

LED의 긴 핀을 라즈베리파이의 40번 핀에 연결하고 LED의 짧은 핀을 39번 그라운드에 연결합니다.

GPIO로는 21번에 해당해서 소스코드에는 21이라고 적어주었습니다.

실행시켜보면 LED가 5초 정도 깜빡이다가 중지되고 프로그램이 종료되는 것을 볼 수 있습니다.

sudo node index.js

나머지 예제들은 다음 링크에서 확인해보세요.

https://github.com/fivdi/onoff/tree/master/examples

참고

[1] https://github.com/fivdi/onoff

[2] https://stackoverflow.com/a/52109489

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Javascripting Your RaspberryPi

There are a few steps that you will need to complete to get your Raspberry Pi set up. I recommend you do the following:

1. Install Raspbian on an SD card.

2. Run through the basic Raspbian setup process. Log in.

3. Connect your RPi to the internet.

4. SSH into your Raspbian machine through the terminal (Mac/Linux users) or Putty (Windows users).

Everything you need to do can be done through the terminal via SSH and a few basic shell commands. Here are a few Linux shell commands you will need throughout this tutorial:

ifconfig – gives you network information

apt-get – used for installing programs

apt-update – used to get latest repositories

nano – used to edit/create text files

mkdir – used to create a directory

cd – change directory

I recommend that you use the following guides if you have any problems with the steps above.

Install Raspbian

https://www.instructables.com/id/How-to-install-Ras…

Raspbian Wifi connectivity

https://www.raspberrypi.org/documentation/configur…

Putty Download

http://www.chiark.greenend.org.uk/~sgtatham/putty/…

SSH tutorials for your OS or preferred SSH client can be found on YouTube.

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