The BeagleBone Green

The BeagleBone Green

Something I have been asked quite often is why anyone would chose the BeagleBone Green (BBG) over the Raspberry Pi 3 (RPi 3). Often they point to the costs, and how the RPi 3 has a 1.2Ghz quad core while the BBG is a single core clocked at 1GHz. They often will then compare the RAM, the fact the BBG doesn’t have HDMI (while the BeagleBone Black did), and the larger community of the RPi 3. I always answer with a question: “What type of projects are you interested in?” I get all kinds of answers to this – I love the diversity! About ⅔ of those who ask are looking for something to tinker with and learn more about embedded systems with, and the remaining ⅓ have a specific project in mind. Here is how I break it down for them.

The RPi 3 is great if you want a small desktop machine or are just interested in small scale projects which you don’t plan to expand. It does have an amazing community and it does have great technical specs – it is designed with the goal that it will be used as a desktop computer by some people. It is a cheap and effective way to teach those who use computers but don’t understand them how they work. It is suited for beginners and even professionals alike, though it does have some limitations. It also comes with wifi and bluetooth capabilities which the BBG does not have, though the BeagleBone Green Wireless does. 

Communication with hardware is important in embedded systems. The RPi 3 is limited in its ability to interface with sensors and communicate with other hardware. It features 26 GPIO pins, but 9 are being used by default, and the last 17 are all set as input with the exception of GPIO 14 & 15. Setting up the RPi 3 do use these GPIO for advanced projects takes a bit more more, but it doable and there are plenty of walkthroughs!

The BBG is not meant to be a desktop computer or a media machine. This is a single board computer (SBC) which is meant to control and interface with other hardware. The most important feature for this is the 2 32-bit PRUs (programmable real-time units) onboard. These PRUs are what allow the BBG to shine.
The way I think of PRUs are as separate processors that share the same memory and peripherals as the normal 1GHz processor. The difference is that each instruction in the PRU takes only 1-cycle to complete. This allows you to know exactly when a signal will be sent or received and a command executed guaranteeing that something will happen on an exact time. This is of critical importance if you are trying to control the stability of a system such as a motors on a robot or drone. This is something the RPi 3 requires a HAT or shield to do, this will be both slower and add to the complexity of the hardware.

The last two defining features of the BBG are the up to up to 69 GPIO – that is a significant increase over the RPi3 and allows for the BBG to control up to thousands of LEDs, and the BBG’s ability to accept analog signals with it’s 8, 7 channel 200KHz 12-bit ADCs. Again this is possible if you use a HAT or shield for the RPi 3. While we are speaking of hardware accessibility I should mention the BBG also has 2 Grove connectors onboard, one for UART and one for I2C. If you aren’t familiar with our Grove system it is a good way to do quick prototyping without the need of soldering or creating your own library for sensors/actuators. 

Finally, while not a feature it is important to note that the BeagleBone Green is open source. This means you can look up the schematics and the components to create your own version. This is important if you want to manufacture your own custom board. The RaspberryPi 3 requires a license to manufacture and only a select few design houses can help customize the board for your project.

The BBG does have its own weaknesses as well. While you can put on a shield to get video connection the experience is not as smooth as what you would get with the RPi 3. This means that if you want a cheap easy to use desktop like computer the BBG is not the best solution. The community is also smaller meaning that you will be able to find support for your problems, but less likely to find a tutorial to help guide you through every step of your project. Also pricing – the BBG is a bit more expensive at $44 compared to the RPi 3’s $35. Still if you want to play with real time functionality but retain the ease of use of a linux environment  the $9 difference should not dissuade you. Especially if you are looking for hardware to help you scale. 

Both the Raspberry Pi 3 and the BeagleBone Green provide makers and engineers with the power and ability to create some pretty powerful and amazing stuff. If you want to use your board like a computer or want to create some multimedia projects the Pi is typically the better solution. If you want to play with more hardware, control physical systems, or scale your project then the BeagleBone Green is better suited for your task.