Connecting Keyboards and Pointing Devices

For input, each Raspberry Pi computer will need a keyboard and a pointing device.

In most cases, USB keyboards and pointing devices are the best choice. You can connect them in moments by plugging them into the USB ports on the Raspberry Pi computer; they work during setup, enabling you to give commands; and you may not even need to configure them afterward.

If you need to use Bluetooth keyboards or pointing devices, you’ll need to set them up after booting the Raspberry Pi computers. See the section “Connecting a Bluetooth Keyboard or Pointing Device,” later in this chapter, for instructions.

Connecting Displays

Connect a display to each Raspberry Pi computer using a suitable connection type:

• HDMI: This is the Raspberry Pi computer’s preferred means of output, so it’s the best choice if the display has an HDMI input.

• DVI: Connect the display using an HDMI-to-DVI cable.

• DisplayPort: Connect the display using an active HDMI-to-DisplayPort adapter.

• VGA: Connect the display using an active HDMI-to-VGA cable.

• Composite: For a display with a single composite input, use a composite cable with a single RCA connector at each end. For a display with separate video and audio inputs, use a cable that has a single RCA connector at one end and three RCA connectors at the other end. Plug the single RCA connector into the Raspberry Pi computer’s composite port. On the display, connect the yellow RCA connector to the video input, the red RCA connector to the right audio input, and the white or black RCA connector to the left audio input.

Connecting Audio

If you’re using HDMI displays with built-in speakers, the HDMI cable carries the audio output from the Raspberry Pi computer to the display along with the video output, so you don’t need to make any further connections. If you’re using HDMI displays with audio outputs for external speakers, connect any speakers you’ll be using to the audio outputs.

If the connection type for a display doesn’t carry audio, connect an audio cable to the Raspberry Pi computer’s composite port and to the input on the display or speakers.

Connecting Power

Next, connect a power supply to the micro USB power port on each Raspberry Pi computer. This is straightforward, but here are three quick points to bear in mind:

• Right type of power supply: Make sure each power supply is the right kind for the Raspberry Pi model. See the section “Choosing Power Sources for Your Raspberry Pi Computers” in Chapter 2 for more information about power supplies and details of the power requirements of Raspberry Pi boards.

• Keep the power off for now: Don’t connect the power supply to power yet unless you’re using a power socket with a switch that you can keep turned off for now.

• Secure any extension sockets: Extension sockets can be a big help for sorting out power, especially ones that have a switch for each socket, enabling you to turn on or off the power to Raspberry Pi computers without unplugging them or their power supplies. If you’re using extension sockets to provide power to the computers and their displays, secure the extension sockets in place so that they can’t move around and drag the Raspberry Pi computers. For example, some extension sockets include screw holes for securing them to walls or furniture; others have recesses that slide onto two exposed screw-heads for quick mounting.

Connecting Ethernet

If you’ll be using Ethernet connections for the Raspberry Pi computers, connect an Ethernet cable to each Raspberry Pi computer’s Ethernet port and to the network hardware—for example, to a wall plate, to a switch, or to a router.

Powering on the Displays

Before you boot the Raspberry Pi computers, make sure that the displays are powered on and that they’re set to receive input on the appropriate port, such as HDMI. This is important because if a Raspberry Pi computer doesn’t detect a display on the HDMI port, it will output video on the composite port instead.

Booting the Raspberry Pi Computers

Boot the Raspberry Pi computers by supplying power to them—for example, by plugging the connected power supply into a power socket or turning on the switch on a switched socket.

If all is well, each Raspberry Pi computer will boot, and you’ll see the command-line interface, a login screen, or the desktop, depending on how you configured Raspbian.

If a Raspberry Pi computer doesn’t boot, check its connections and try again. If it still doesn’t work, turn to Chapter 8 for troubleshooting suggestions.

Connecting a Bluetooth Keyboard or Pointing Device

Now that the Raspberry Pi computers are running, you can add Bluetooth keyboards and pointing devices to replace the USB devices where necessary. Follow these steps to add a Bluetooth device:

1. Click the Bluetooth icon on the panel to display the Bluetooth pop-up menu (see Figure 6-1).

   

   Figure 6-1. To connect a Bluetooth device, click the Bluetooth icon on the panel and then click Add Device on the Bluetooth pop-up menu .

2. Click the Add Device item to display the Add New Device dialog box (see Figure 6-2).

   

   Figure 6-2. In the Add New Device dialog box, click the Bluetooth keyboard or pointing device, and then click the Pair button.

3. Click the entry for the Bluetooth keyboard or pointing device. This example uses a keyboard.

4. Click the Pair button. For some Bluetooth keyboards, the Pairing Device dialog box then opens, prompting you to enter a pairing code (see Figure 6-3). Type the pairing code on the keyboard, confirming that it’s the correct device, and then press the Enter key.

   

   Figure 6-3. If the Pairing Device dialog box prompts you to enter a pairing code, type it on the keyboard and press the Enter key.

5. Next, Raspbian displays progress dialog boxes as it establishes the connection. When it has done so, it displays the Connected Successfully message in the Pairing Device dialog box (see Figure 6-4).

   

   Figure 6-4. When the “Connected successfully” message appears in the Pairing Device dialog box, click the OK button to finish the pairing process.

6. Click the OK button. You can now start using the Bluetooth keyboard or pointing device.

Identifying Your Raspberry Pi Computers

To keep your classroom running smoothly, you’ll likely want to be able to identify your Raspberry Pi computers, both directly—by looking at a Raspberry Pi computer itself—and via the network.

You can give yourself a way to identify the Raspberry Pi computers directly by labelling them, preferably on a part of the case that can’t easily be swapped between computers. A tape labeler is easy and gives a neat look; but writing on cloth tape—or even directly on the cases—can work just fine too.

You can use MAC addresses , hostnames, and static IP addresses to identify your Raspberry Pi computers via the network. The following sections explain how to determine MAC addresses and how to assign hostnames and static IP addresses to your Raspberry Pi computers.

cat /sys/class/net/eth0/address

cat /sys/class/net/wlan0/address

hciconfig

hci0:   Type: BR/EDR  Bus: UART
        BD Address: B8:27:EB:32:F7:90  ACL MTU: 1021:8  SCO MTU: 64:1
        UP RUNNING
        RX bytes:773 ACL:0 sco:0 events:50 errors: 0
        TX bytes: 2540 ACL:0 sco:0 commands:50 errors:0        

Configuring Network Connections

Your Raspberry Pi computers can connect to the network via either Ethernet or Wi-Fi :

• Ethernet: If you plugged in the Ethernet cables before booting the Raspberry Pi computers, chances are that the computers have connected to the network. You may need to configure the network connection; see the section “Configuring the Network Connection for a Raspberry Pi Computer,” later in this chapter.

• Wi-Fi: Unless you already set up a Wi-Fi network connection on the Raspberry Pi computers, you’ll need to connect them to the Wi-Fi network now. See the next section for details.

Connecting to a Wi-Fi Network

Follow these steps to connect a Raspberry Pi computer to a Wi-Fi network:

1. If the Raspberry Pi computer doesn’t have a built-in Wi-Fi adapter, plug a compatible Wi-Fi adapter into a USB port.

2. Click the Wi-Fi Networks icon at the right end of the Panel to display the list of available Wi-Fi networks (see Figure 6-5).

   

   Figure 6-5. Open the Wi-Fi Networks pop-up menu and click the network to which you want to join the Raspberry Pi computer. At this point, the Wi-Fi Networks icon appears as two blue arrows, one pointing up and the other pointing down.

   Note The built-in Wi-Fi on the Raspberry Pi 3 Model B is 2.4 GHz only. If your school has Wi-Fi access points providing 5 GHz networks, the Raspberry Pi 3 Model B will not show them.

3. Click the Wi-Fi network you want the computer to join. If the Wi-Fi network uses security, a dialog box whose title bar shows the network’s name (SSID) appears, prompting you for the Pre Shared Key (see Figure 6-6).

   

   Figure 6-6. Open the Wi-Fi Networks pop-up menu and click the network to which you want to join the Raspberry Pi computer.

4. Type the preshared key (the password) for the network and click the OK button. The Raspberry Pi computer connects to the network.

When the Raspberry Pi computer has established the connection to the Wi-Fi network, the Wi-Fi Networks icon appears as a Wi-Fi symbol showing an access point with arc-like waves radiating from it. To see which Wi-Fi network the Raspberry Pi computer has connected to, hold the pointer over the Wi-Fi Networks icon and look at the pop-up balloon, which also shows the IP address and netmask (see Figure 6-7).

Figure 6-7. Once the Wi-Fi connection is established, the Wi-Fi Networks icon appears as a Wi-Fi symbol. You can hold the pointer over the icon to display a pop-up balloon showing the Wi-Fi network and the IP address.

Forgetting a Wi-Fi Network

When you enter the preshared key for a Wi-Fi network, Raspbian automatically stores it for future use. Storing the key enables the Raspberry Pi computer to connect quickly to the Wi-Fi network when the computer is within range, saving time and effort.

Sometimes, however, you will want to prevent a Raspberry Pi computer from connecting to a particular Wi-Fi network again. Unlike most operating systems, Raspbian doesn’t have a graphical tool for “forgetting” (removing) Wi-Fi networks it has used; instead, you need to edit the wpa_supplicant.conf file and remove the network’s name and password.

Click the Terminal icon on the Panel to open a Terminal window, and then give the following command:

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf  

Terminal opens the wpa_supplicant.conf file in the nano editor, where you’ll see details of the control interface and a list of Wi-Fi networks and preshared keys. Here’s an example:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=US

network={
        ssid="SchoolLab01"
        psk="correcthorse"
        key_mgmt=WPA-PSK
}

network={
        ssid="SchoolLab02"
        psk="batterystaple"
        key_mgmt=WPA-PSK
}

Delete the entry for the network you want to stop using, starting with network={ and ending with }. Press Ctrl+O to give the command to write out the file, and then press the Enter key to accept the existing name. Finally, press Ctrl+X to exit the nano editor.

Configuring the Network Connection for a Raspberry Pi Computer

If your network uses a DHCP server, each Raspberry Pi computer automatically requests an IP address and other network settings from the server when it tries to join the network. For some computers, however, you may want to configure the network connections manually. For example, you may need to configure static IP addresses for some Raspberry Pi computers, as discussed earlier in this chapter.

Follow these steps to configure either an Ethernet connection or a Wi-Fi connection:

1. Right-click the Networks icon on the panel to display the shortcut menu.

2. Click the WiFi Networks (dhcpcdui) Settings item to display the Network Preferences dialog box (shown in Figure 6-9 with some settings chosen).

   

   Figure 6-9. Use the Network Preferences dialog box to set a static IP address for a Raspberry Pi computer. You can also specify the address of the router and the DNS servers and add any DNS search domains needed.

3. On the Configure row, make sure the left pop-up menu shows Interface rather than SSID.

4. Still on the Configure row, click the right pop-up menu and choose the interface you want to configure. Choose eth0 for Ethernet; choose wlan0 for Wi-Fi.

5. If necessary, click the Clear button to clear the current configuration details.

6. Check the Automatically Configure Empty Options check box if you want Raspbian to automatically detect values for network parameters you don’t specify.

7. In the IP Address box, type the static IP address you want to assign the computer. Leave this box blank if you want the computer to get an IP address via DHCP.

8. In the Router box, type the IP address for the router. Leave this box blank if you want the computer to get the router’s address via DHCP.

9. In the DNS Servers box, type the list of DNS servers the computer is to use. Put the primary server’s address first and the secondary server’s address second, separated by a comma. Here, too, you can leave the box blank if you want the computer to get this information via DHCP.

10. In the DNS Search box, type any search domain you want to have automatically appended for DNS lookups. For example, you might enter your school’s domain here to cause any unqualified searches to be run using that domain.

11. Click the Apply button to apply your changes.

12. Click the Close button to close the Network Preferences dialog box.

To make your changes take effect, you need to restart the Raspberry Pi computer. To do so, choose Menu ➤ Shutdown to display the Shutdown Options dialog box, and then click the Reboot button.