Rui Santos - BeagleBone For Dummies

BeagleBone For Dummies

Published by: John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, www.wiley.com

Copyright 2015 by John Wiley & Sons, Inc., Hoboken, New Jersey

Media and software compilation copyright 2015 by John Wiley & Sons, Inc. All rights reserved.

Published simultaneously in Canada

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Library of Congress Control Number: 2014954656

ISBN: 978-1-118-99291-3 (pbk); ISBN 978-1-118-99292-0 (ebk); ISBN 978-1-118-99305-7 (ebk)

Manufactured in the United States of America

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Appendix A

One frustrating thing about electronics and computation is that quite often, things dont work as they should. You find yourself angrily asking Why?!, and you may even blame the BeagleBone for not doing what you asked it to.

Then you find the source of the issue, and you bring your palm to your face when you realize how simple the mistake was. You may even apologize to your computer for having unjustly accused it of causing the problem.

This appendix describes some common issues and explains how to solve them, and it provides a few tips and tricks on how to tackle problems that arent included in these pages. We hope there wont be many!

This section presents a few typical mistakes that even the most experienced programmers and electronics enthusiasts often experience.

Issue:

The BeagleBone doesnt power on. Its built-in light-emitting diodes (LEDs) arent lighting up.

Possible causes:

• Not enough power or faulty USB cable/USB port. This may happen if you have too many peripherals connected to the BeagleBone and youre feeding it through a USB cable.
• You have a short circuit somewhere in your external wiring. A short circuit causes the board to shut down to prevent any further damage but a short circuit always does some harm.

Solutions:

• Disconnect some peripherals; try a different USB cable or a different USB port. If these remedies fail, connect an external DC power source that can provide more current than a USB cable can.
• The problem might also be in your external DC power source, so if you have another one, try it.
• Double-check your circuit to ensure that everythings wired up correctly. If your board went off immediately after establishing a connection, dismantle that connection, and wire it correctly. If not, grab a multimeter, and check the continuity. If theres a short circuit, you hear the beep of a connection where it shouldnt be.

  You can read all about how to use a multimeter at www.dummies.com/extras/beaglebone .

• If none of the aforementioned solutions works, do a full power cycle. Press your BeagleBones power button for about 10 seconds. It should shut down and start over. This process isnt the same as rebooting.

If all these attempts fail, perhaps contacting BeagleBoard.org support is the way to go. The board may be damaged, and you may have to fill out an RMA (Return Merchandise Application) form. This page should help you: http://beagleboard.org/support .

Issue:

The BeagleBone is on, but you arent able to log in via Secure Shell (SSH).

Possible causes:

• Faulty USB/Ethernet cable.
• Your USB cable is power-only; it doesnt feature pins for data transmission. In this case, the user LEDs of your BeagleBone light up as normal.
• The default IP to connect through Ethernet has changed, so you cant log in by typing beaglebone.

Solutions:

• To address the first two causes, attempt to establish the connection by using other cables. Try to connect your Mini USB cable to other devices to see whether it can establish a communication.
• If you cant connect through an Ethernet cable, find the BeagleBones IP address and type it in the terminal window or PuTTY.

  There are several ways to list all the IP addresses in the network that your computer is connected to:

  • For Windows, you can install the Advanced IP Scanner ( www.advanced-ip-scanner.com ). All you have to do is click the Scan button.
  • For Linux and Mac OS, you need to install nmap by using the command sudo apt-get install nmap . Then find your own IP address in your network by typing ifconfig in the terminal window. Below eth0 , look for inet addr . You should see a number with four fields separated by dots. The first three fields are the same for all devices connected in the same network. Thus, if your IP address is something like 192.168.1.12 , all other IP addresses have the format 192.168.1.X . To find all IP addresses in that format, type