Introduction

Syncing files automatically from a Raspberry Pi is a good idea to make sure that nothing gets lost the Pi breaks. The problem is that due to the unusual ARM architecture, most of the common methods for syncing are not available. Dropbox does not have an ARM package. Google Drive never had a Linux client. There are ways around these limitations either by use of lower quality third party applications to interface with the major sync solutions or by use of open source and self hosted solutions.

There are some great libraries that make it really easy to use the pins on the Raspberry Pi. It has relatively few pins and are a little less powerful than what you might expect from a microcontroller. Aside from those limitations, you should also keep in mind that pin manipulation is not done in a real time environment. Unlike an Arduino, which only runs your program, the Raspberry Pi takes turns running many programs like a normal desktop. While your program might be able to recieve the majority of the processor's attention, it will not be able to use all of it. Likewise, timing events may be slightly less reliable too. As great as Python is, it is even less reliable because of a process called garbage collection. It is not a problem for most situations, but it is definitely something to keep in mind.

There are two kinds of numbers to specify which pin you want to use. There is the physical pin number, which altenate sideways increasing from top to bottom. For nearly any device, if you look carefully on the board, there is an indicator near the "1" pin on a header. This is even true of integrated circuit (IC) chips. Unlike with ICs, orienting the pins with that indicator in the top left, the pin numbers are increased from left to right and top to bottom. The reason this appears differently on P5 is because the indicator is on the bottom side.

The BCM GPIO number is the number that the processor uses to differentiate the pins. Obviously, pins like 5V and GND cannot be addressed since they only have their one purpose and cannot be changed. As a result, the BCM number is different than the header number. It is important to keep track of which addressing system you are using. It might help you to remember that BCM is a reference to the signal name on the Broadcom datasheet for the processor on the Raspberry Pi.

You should also know that the pinout information only pertains to the revision 2 version of the board. You can tell that you are not using a revision 1 board by the presense fo the P5 holes. P5 was added in revision 2. Revision 1 is essentially the same, but has quite a few pins missing.

Setup

The Raspberry Pi minimally needs a micro USB-B cord to power it. If you have a phone charger, aside from an iPhone, it will likely use this cable since the EU made it mandatory for smartphones. So, you probably don't even need to buy another wall adapter or cable if you look around. You can also plug it into a computer to power it, though you are not able to communicate with the computer over it. Additionally, an Ethernet cable connecting it to the same LAN as a computer is one of the easiest ways to get started. Unless you can figure out what IP address the Raspberry Pi will get, you will also need a keyboard and a monitor or tv capable of using either HDMI or the yellow RCA connector.

The Raspberry Pi does not come with an SD card, which you will also need. You will need to install an operating system on it as well, so it should be at least 4GB to be comfortable. Some SD cards are faster than others. Higher speed is denoted by a higher "class" number. This class will primarily effect install, startup, and upgrade times and there is no mandatory minimum.

Sure, the BeagleBone and BeagleBone Black come with an ethernet port on them, but why have to get another cable out? You might not even be anywhere near the router. The BeagleBone images automatically do network communcations over USB, as shown by how you can go to 192.168.7.2 from your browser to see the BeagleBone start page and http://192.168.7.2:3000/ to use the Cloud9 editor hosted on the BeagleBone. The problem is that the host computers do not usually relay network traffic to new interfaces. I don't know why not. It would be nice if you could just connect stuff to any connection and it'd always work, but it's not hard to set up NAT and such once you know how to do it. The connection over USB might be slighlty slower than the dedicated connection, since USB is slower and is sharing the connection with things JTAG communication and mass storage. For all I know, though, the ethernet on the BeagleBone is actually controlled by the same USB controller, so it might not be at all different!

Since the BeagleBone (and the Raspberry Pi) is Linux based, and has usb ports, it is actually very easy (and cheap) to make a security camera system. All you need are USB webcams. Just about any will do. I got four for $16 on Amazon. More expensive ones might say they have higher resolution, but what they are actually reporting is the still photo quality, not streaming video quality. Unless you get a USB 3.0 webcam, which would not be supported by either hobbyist computer, it is impossible to stream HD (1080) video, but some might be able to 720.

Introduction

I had gotten a joystick a while ago and wanted to do something different and interesting with it. After coming up with and discarding a bunch of other ideas, I came up with the Arduino Sketcher. The ideas was to make something similar to an Etch-a-Sketch but uses the joystick instead of two dials. The computer would serve as the sketching pad while to Arduino relayed all the commands sent by the user. This project uses both Arduino and Python and turned out to be fairly simple to implement.

Introduction

Joysticks have become a common tool among various devices, such as gaming controllers. They can be an interesting addition to projects as well. Joysticks are fairly simply components that use two potentiameters to give the readings from two axes. They may also include a button to see if the user has clicked the joystick.

Introduction

Angstrom Linux is what ships on the BeagleBones. It's kind of terrible because I think everyone when they first get it will say, oh I should run opkg upgrade so that everything is up to date. Guess what? That breaks the boot. It won't startup anymore. I don't know how to fix it or what goes wrong. You'll get three LED's on, no USB connection on either the mass media or network, and it'll never come online on the LAN because it won't start up. 

If you want things to be up to date, you may want to install Ubuntu.

On the other hand, it is pretty lightweight and is pre-configured in a lot of ways that other distros don't have by default. For example, the cloud9 editor is kind of nice.

Installing Images

Whether you have a BeagleBone or BeagleBone Black, you can use the Angstrom-Cloud9-IDE-GNOME-eglibc-ipk*.img.xz

They both run ARM7 and the image has the NEON optimization. The image for the BeagleBone Black might have additional features, but it's the same Angstrom with less features as far as I can tell.

sudo su
xz -cd ./Angstrom-Cloud9-IDE-GNOME-****.img.xz > /dev/sdd

About each LED

There are four user LEDs on the BeagleBone. You can modify them, but they each have their own purposes by default. USER0 is the closest to the top in the picture at the right, and USER3 is the bottom one closest to the ethernet port.

• USER0 is the heartbeat indicator from the Linux kernel.
• USER1 turns on when the SD card is being accessed
• USER2 is an activity indicator. It turns on when the kernel is not in the idle loop.
• USER3 turns on when the onboard eMMC is being accessed.

You can change each of the LED's behaviors at the following locations:

/sys/class/leds/beaglebone\:green\:usr0/
/sys/class/leds/beaglebone\:green\:usr1/
/sys/class/leds/beaglebone\:green\:usr2/
/sys/class/leds/beaglebone\:green\:usr3/

Yeah, the LEDs are blue, but the folder is called green for some reason. Also, those colons make BASH freak out a bit, so pay attention to escape them.

If you explore those directories, things start to get interesting.

Pinout Tables

These tables are based on the BeagleBone Black System Reference Manual (Creative Commons) by Gerald Coley of BeagleBoard.org. They aren't really available anywhere else on the internet, so I thought I'd transcribe them into a more available format.