Evolution of a Blog

This blog has evolved as I have as a maker. It starts at the beginning of my journey where I began to re-tread my tires in the useful lore of micro electronics and the open-source software that can drive them. While building solutions around micro-electronics are still an occasional topic my more recent focus has been on the 3D Printing side of making.

Saturday, September 21, 2013

Raspberry Pi vs BeagleBone Black - Expanding on a Review

Some time after I had evaluated the Raspberry Pi versus the BeagleBone Black I came across a really well done comparison of the two platforms by Michael Leonard.  It was originally posted on his blog here and then later it was re-posted to Make here.  There is nothing in the review that would have changed my recommendation, and there is little with which I disagree, but the following are points where my learnings over the past months augment Michael's review.


I had unboxed three Raspberry Pi's (RPi's) before I got my first  BeagleBone Black (BBB).   My first impression of the BBB was to be impressed by how much more professional it looks than the RPi.   Obviously this is a reflection of it being the latest in a family of devices.   I still like the look and feel of it better than the RPi which has a much more "hobbyist" look in my opinion.   I would give unboxing to the BeagleBone Black.  This is the only scoring difference that I would make in Michael's evaluation.

Ease of Setup

I strongly agree with Michael on the ease of initial setup with the BeagleBone Black but would caveat as follows.  There are probably a lot of applications that will never need to boot from the removable micro-SD card but I have one of them and this created some minor complexities similar to what one encounters with the RPi.   The ability to connect the BBB to a host computer using the included USB cable is a very nice feature and one that I am planning to use when the BBB is embedded in it's final home where it will not regularily be network attached.


Another caveat here could be important to someone wanting to use the BBB to talk to things via the built-in Analog Digital Convertor or AIN as called on the BBB:
  • First, and most importantly, if your application is going to use an LCD cape you will not have physical access to the AIN pins, and, it won't matter as the LCD cape monopolizes the ADC chip so even if you had physical access to it...the AIN will still not work for you.
  • Second, and this is minor compared to the above, the AIN being based on 1.7 volts is a pain in the butt!  Sure you can easily do a voltage divider to get your source, which is probably 5v, down to what the BBB needs, but it is a pain.  I have also read, but not verified myself, that the accuracy of the onboard AIN can be impacted by noise on the board.
My solution to the above was to implement an offboard ADC (the MCP3426) that communicates with the BBB via I2C.   Not only do I not have to do any voltage dividing but the device that I am using has the option of doing 12, 14, 16, or 18 bit accuracy (at reducing speeds).

This certainly does not change the BBB being a clear winner here as you would need an external ADC for the RPi in any case.

Graphical Showdown

I don't disagree with anything that Michael states here but I would give the BBB some points for the availability of three LCD capes of varying sizes at price points well below what I have found to be available for the RPi.   They integrate extremely easily, work well, and look great.  Yes, I know, credit for this is given in the expandability section.  Just sayin'


I agree with the scoring on this area but not for the availability of the Arduino add on board (though I do think it is pretty cool).   I think the chances of needing an Arduino, if you have a BBB, are less than if you have an RPi but if you do need one to take advantage of a shield, there are lots of ways to connect said Arduino.   I would give the edge to the RPi simply because of the wide variety of accessories that have entered, or are entering, the market given the popularity of the RPi.   I think that some of the expansion boards for the BBB might be a little nicer, and in the case of the LCD, cheaper, than for the RPi but the size of the RPi ecosystem gives them an edge.


The other areas where I agreed with Michael did not get a comment...but this one deserves a shout-out.  The community for the BeagleBone Black has been helpful but there just does not seem to be many folks out there.   On the other hand the RPi community is out there in droves and seem particularly happy to help with problems posted on their message boards.  I also greatly prefer the RPi forum which is based on phpbb rather than the Google Groups approach used by the BBB.

In any case, forum tools aside,  I hope that the dynamism of the BBB user community will improve over time as the BBB sells more units but for now it is, as Michael's review states, clearly a win for the Raspberry Pi.


This is not something that Michael talked to but that I needed to add based on my experiences.   I will freely admit that this could be "just me".

You can fry any electronic device, and I am proof to this statement, but one of the strengths of the Arduino is it's ability to resist ham-fisted users like myself.

The Raspberry Pi is clearly more sensitive than the Arduino but I managed to fry one of them.  It turns out that it was a model that did not include the poly-fuses that newer boards now support.   On a later attempt to smoke another, newer RPi, the poly-fuse did it's thing and some hours later, when things cooled down, the RPi came back to life!

The BeagleBone Black, in my hands anyway, has been expensive.  Two of them have been into the Beagle Hospital and I am now a little gun shy.  I would strongly recommend that a high degree of caution be taken when working with a BBB connected to the external world.   Never connect and disconnect hardware with the power on (should probably go without saying)!   Never have the gear to which you are interfacing with powered on before the BBB (came as a little bit of a surprise)!

I am not a hardware guy, but, I can't help but wonder why the RPi would seemingly put poly-fuses to good use but they are not appropriate for the BBB (according to someone associated with the device)?   [Yes, I know, you can not protect against all forms of ham-fisted'ness but maybe against some would be nice.]


Interestingly, my original evaluation of the two boards leaned towards the BBB largely because of the lack of an ADC on the Raspberry Pi.  Learning that the ADC is not accessible when the LCD Cape is on the BBB defrayed that advantage but the quality of the LCD, and the integrated nature of the board and the LCD, have become the reason to continue my path to production on the BBB.

On the other hand, I have the code that I have written for the BeagleBone Black running pretty much seamlessly on the Raspberry Pi so if I needed to make a change I can do so.  This is a great testament to the open-source world within which both boards reside.  Cool eh?

Monday, September 2, 2013

Minimum Setup for a GitHub Software Repository

Previous projects have had me using subversion with SmartSvn as a GUI.  I had a server setup on my home network but wanted an external server but never got around to setting one up.   For this project I decided to go with GitHub.  It is, after all, the home of much open source software, is easy to use, is free for public repositories (and cheap for private ones), and has both graphical and command line utilities for the client.

Once you have setup your repository on GitHub the following commands will add your project to the new repository:
  • touch README.me git init
  • git add README.md
  • git commit -m "First commit"
  • git remote add origin https://github.com/ThamesWill/Physical-Interface-Demo
  • git push -u origin master
Obviously replacing my name and project (ThamesWill and Physical-Interface-Demo) with your name and project!

Then to update your repository you do the following
  • git add *.*
  • git commit -m 'Initial adds'
  • git push -u origin master
You will be asked for your GitHub username and password.  Once the push is complete you will see your code in the repository.   Subsequent pushes will result in the updates being change tracked so you can see what code changed when something goes boom in the night after an upgrade.

There are a lot of other features of both the local client and the remote repositories but the above are a minimum that I use to manage 'The App'.

Sunday, September 1, 2013

Back with a (Big) New Project

There has been a period of silence over the past months as I had been given the opportunity to apply some of my new technical skills in the Computing Physical Interface space.   In particular a friend offered me the opportunity to build an instrument based on a single board computer with a physical interface to a piece of laboratory equipment.   No, there is not much danger of me making money here, and I have been interested enough in it to invest in a number of new pieces of kit, but this pro-bono project has 'def peaked my interest.

Over the coming weeks and months I will attempt to look back on the past several months to document some of my learnings.   I am going to backdate these posts to approximate when I actually might have gained the knowledge!