EBC Exercise 02 Out-of-the-Box, Bone
Embedded Linux Class by Mark A. Yoder
The BeagleBone can do many neat things right out of the box using just the USB cable and SD card that come with it. Before hooking up anything, if you are running Linux or OSX on your host computer, open a terminal at run:
host$ ls /dev/tty* > /tmp/tty
This will record what devices are present on you host computer. Once you plug the bone in it will create a new device. Windows users don't have to do anything here.
Install the SD card (not the one that says Linux SDK on it) and attach the Bone to a host computer via the USB cable. The little USB connector goes to the Beagle in the connector on the bottom of the board near the Ethernet connector. Connect the large end of the USB cable to a host computer. The host can be either Linux, Mac, or Windows (though if you are doing development, consider running Linux on the host.) I give instructions for each.
The Beagle, powered via the USB, will boot up. You should initially see two LEDs blinking, near the Ethernet connector. The one labeled 0 blinks a heartbeat pattern. LED 1 blinks when the SD card is being accessed. After about 30 seconds LED 1 will stop blinking. The Bone is booted.
Here are some of the things it can do.
Here's a nice overview of the BeagleBone. It shows how to work with it using a Windows host.
On your host you will notice a new folder appearing. On Linux and OSX it's call BEAGLE_BONE. On Windows it's Beagle Bone Getting Started. Open it up and look around. The README.html gives lots of information about getting going with the Bone. Look at it in detail after going though this page.
When you are doing exploring the files, eject the drive (don't select SAFELY REMOVE DRIVE). Once the drive is ejected, the network will start up over the USB.
Built in USB to serial adapter
The Beagle xM has a serial port connector on board, but the Bone doesn't. Instead you access the serial port through the USB connector. The trick is figuring out how to access it.
Run the following:
host$ ls /dev/tty* > /tmp/tty2 host$ diff /tmp/tty* ttyUSB1 host$ screen /dev/ttyUSB1 115200 (Linux) host$ screen /dev/tty.usb*B 115200 (OSX)
The first line lists what devices are out there. The second compares that list to the list made earlier. What appears is the USB to serial device on the Bone. The last line starts a serial port program that attaches to that device. Notice the ttyUSB1 is the same string as returned by the diff command.
To find where the serial port appears in Windows, click on the start menu and search for Device Manager and run it.
Select Ports and look for USB Serial Port. In my case the port appears at COM6.
Start up a ECE497_Tips_and_Tricks#Serial_Port serial port program and connect. The baud rate is 115200.
Hit RETURN and you'll see the following. Login as root and look around.
.---O---. | | .-. o o | | |-----.-----.-----.| | .----..-----.-----. | | | __ | ---'| '--.| .-'| | | | | | | | |--- || --'| | | ' | | | | '---'---'--'--'--. |-----------' '-----'-'-'-' -' | '---' The Angstrom Distribution beaglebone ttyO0 Angstrom v2012.01-core - Kernel 3.2.5+ beaglebone login: root Last login: Fri Jul 13 01:28:06 UTC 2012 on ttyO0 root@beaglebone:~#
One of the slickest features of the Bone is it's ability to access the Internet through the USB connection. The network connection starts up after you've ejected the BEAGLE_BONE drive that appears. Do it now.
After ejecting, run:
host$ ifconfig eth0 Link encap:Ethernet HWaddr 00:18:8b:72:b8:c2 inet addr:22.214.171.124 Bcast:126.96.36.199 Mask:255.255.255.0 inet6 addr: fe80::218:8bff:fe72:b8c2/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:8481193 errors:0 dropped:0 overruns:0 frame:0 TX packets:1871287 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3172154531 (3.1 GB) TX bytes:203188180 (203.1 MB) Interrupt:19 eth4 Link encap:Ethernet HWaddr d4:94:a1:39:ff:ff inet addr:192.168.7.1 Bcast:192.168.7.3 Mask:255.255.255.252 inet6 addr: fe80::d694:a1ff:fe39:ffff/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:8 errors:0 dropped:0 overruns:0 frame:0 TX packets:6 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2775 (2.7 KB) TX bytes:1234 (1.2 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:37315 errors:0 dropped:0 overruns:0 frame:0 TX packets:37315 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:3665320 (3.6 MB) TX bytes:3665320 (3.6 MB)
You'll see at new network has appear, eth4 in my case. The IP address is 192.168.7.1. There's a good chance the Bone is at 192.168.7.2. Try connecting to it.
host$ ssh -X 192.168.7.2 beagle$
You are now logged into the Bone through the network. This is much faster than the serial port (.115M vs. 100M) and supports many interesting network things. The only problem is, the Beagle doesn't know how to access the Internet through the host. Get back to the host computer by entering RETURN ~ ^Z. That is, hit RETURN, then ~ (it's up there near the ESC key) and then Ctrl-Z. This gets you back to your host, but leaves the ssh connection running.
Copy the following lines into a file call host.ipForward.sh
#!/bin/bash # These are the commands to run on the host to setup IP masquerading so the Beagle # can access the Internet through the USB connection. # Inspired by http://thoughtshubham.blogspot.com/2010/03/internet-over-usb-otg-on-beagleboard.html if [ $# -eq 0 ] ; then echo "Usage: $0 interface (such as eth0 or wlan0)" exit 1 fi interface=$1 hostAddr=192.168.7.1 beagleAddr=192.168.7.2 ip_forward=/proc/sys/net/ipv4/ip_forward if [ `cat $ip_forward` == 0 ] then echo "You need to set IP forwarding. Edit /etc/sysctl.conf using:" echo "$ sudo gedit /etc/sysctl.conf" echo "and uncomment the line \"net.ipv4.ip_forward=1\"" echo "to enable forwarding of packets. Then run the following:" echo "$ sudo sysctl -p" exit 1 else echo "IP forwarding is set on host." fi # Setup IP masquerading on the host sudo iptables -t nat -A POSTROUTING -s 192.168.0.0/16 -o $interface -j MASQUERADE # Check to see what nameservers the host is using and copy these to the same # file on the Beagle # This makes it so you can connect to the Beagle without using your password. ssh-copy-id root@$beagleAddr # Save the /etc/resolv.conf on the Beagle in case we mess things up. ssh root@$beagleAddr "mv -n /etc/resolv.conf /etc/resolv.conf.orig" # Copy the resolv.conf file to the Beagle. Now the Beagle will use the # same name servers as the host. scp /etc/resolv.conf root@$beagleAddr:/etc # Tell the beagle to use the host as the gateway. ssh root@$beagleAddr "/sbin/route add default gw $hostAddr"
host$ chmod +x host.ipForward.sh host$ ./host.ipForward.sh eth0
This will give you instructions on how to set up your host and will remotely set up your Beagle.
Once ./host.ipForward.sh has been run you can:
host$ fg ssh -X firstname.lastname@example.org (Hit RETURN) beagle$ ping google.com
You should see Google responding. Hit Ctrl-C to stop.
Note: If you are using Ubuntu 12.04 and having an issue connecting to the internet, you may need to add a line to the /etc/resolv.conf file on the Bone. If ping google.com returns an "unknown host" error, this means that the Bone cannot resolve the url google.com to an IP address. Users with an Ubuntu 12.04 host may see this issue because the resolv.conf that Ubuntu uses (and is copied to the Bone in the host.ipForward.sh script) is not compatible with the Bone. The solution is to run the host.ipForward script as normal, then add the line "nameserver 188.8.131.52" above the existing entry in resolv.conf. This configures the Bone to use Google's Public DNS Server.
Congratulations! Your Beagle is now on the network through your host computer.
- go to System Preferences and select Network
- You should see RNDIS/...Gadget. This is the network connection to the Beagle. Select it
- Wait for the IP address 192.168.7.1 to appear
- Click Show All and select Sharing
- Select Internet Sharing
- Select RNDIS/Ethernet Gadget
In a terminal window connect to the serial port
host$ screen /dev/ttyusb*B 115200 beagle$ udhcpc -i usb0 beagle$ ping google.com
This is all nicely shown here in this silent YouTube movie.
Congratulations, you now have a connection to the Internet.
I don't have this working yet.
On the Network
Once you have your Beagle on the network there are many things you can do. Try these from your host.
- Point your browser to 192.168.7.2. You'll see a nice slide show about the Beagle
- Point your browser to 192.168.7.2:3000 to see the Cloud9 IDE running on the Beagle
Embedded Linux Class by Mark A. Yoder