Docker on RaspberryPi

Installing Docker on a RaspberryPi might seems overkill, but it actually works pretty well, even if installing the tools can be a little messier if you don’t know how to do it and you start searching the Internet for clues.

After being intimidated by the many alternatives given to you to overcome the lack of a docker package on the official package repositories you’ll start wondering which might be a secure way to start playing with Docker without compromising your system security: here is what I have done.

The Client and the Server

First thing you need is to have the Docker server along with the command line client installed.

The RaspberryPi Foundation, within their blog, recommend to simply use:

$> curl -sSL | sh

That’s an official shell script which will identify your operating system and architecture (don’t forget we are on an ARM processor) and install the most appropriate binaries.

The Compose

After playing for a while with Docker you’ll start to feel the urgency to use the docker-compose tool, which sadly is another missing element.

I’ve found the simplest way to have it running is by executing the following two commands:

$> sudo apt-get -y install python-pip
$> sudo pip install docker-compose

Othermill Pro – Plastic

It’s a couple of months now the Othermill Pro is beautifully sitting on my desk and after having milled a few PCBs and showed off with my family and friends I feel dauntless enough to try something new.

I’ve got a small selection of end-mills and I didn’t want to break them all straight away with some tough material, so I opted for creating something out of plastic: a few key tags with a name on it could have done the job and milling a softer material should have be painless, right?

Sadly, I couldn’t have been wronger! As you can see from the result shown below, plastic has this unpleasant desire to melt when thermally stressed… As any other newbie I’m in a learning process.


Looking at the outer border it should be clear the end mill was going clockwise and melting begun at 2 o’clock.

When milling plastic you must keep the material as cool as possible, meaning you need to reduce the end-mill friction with the material as much as possible and also add any possible cooling. If the plastic starts to melt it will clog the end-mill, reducing the end-mill cutting efficiency causing an increment in friction and a consequent rise in temperature: a spiral process which results in a very bad milling and also a potentially unrecoverable end-mill.

So this is how I started learning about chip load and chip load chart tables:

chip20load20graphic chip20load20for20common20tool20diameters20inches

I’m not going to lecture you on the subject, mostly because I don’t know enough on this topic. Briefly, in order to minimize temperature rise you want to maximize the chip load thickness, reducing the rubbing effect of the end-mill on the material, which causes temperature raise without any benefit.

As clearly displayed on the diagram above, chip load thickness is determined by axial speed (rpm), radial speed or feed rate (in/m or mm/m) and number of flutes (# teeth):

CLT = feed rate ÷ rpm × teeth

Now, luckily for me, the CAM software I’ve adopted (Fusion 360) already performs those calculations and automatically adjust the parameters accordingly.

So I opted for the thickest suggested chip load on acrylic (0,13 mm) for my end-mill (a 2 flute 0,8 mm) and a very slow rotation speed (100 rpm) in order to give a little breath for the plastic to cool down: to my surprise the end-mill got clogged immediately, even worse than my previous experiments!

Apparently the just acquired knowledge is misleading, or… Should I trust my ears? Even just considering the pitch of the gentle sound emitted by my Othermill Pro I can tell the spindle is not going as slow as I planned! A quick check at the technical specs just to discover the slowest spindle speed is 8500 rpm!

That practically means the chip load was 1/85th of what I was expecting, resulting in my end-mill gently massaging the plastic surface until it turns into a smoking hot glue-ish material perfectly mating with my end-mill!

It’s time for another try, but before ruining my last end-mill (yes, the last run turned my end-mill into a glowing ball of plastic around a metal rod) I wanted to verify how accurate is the spindle speed control on my device.

Surprisingly the Othermill Pro spindle is an open loop circuit. If you are wondering what that means don’t be too ashamed, it was my very same reaction, but a little googling and you discover it means there is no feed back circuit: simply put, the machine doesn’t know how fast the spindle is actually going, it only knows at certain voltages the spindle should run at a certain speed.

Not that it is a crucial information, but given the high quality and accuracy of this CNC I was expecting some feedback, but at a second tough and considering the main aim of the Othermill Pro it does make sense why Othermachine Co. didn’t think about it.

May be I can do something about that…

Github project website

This is nothing new, but apparently not many Github users know about this feature and I’ve recently learnt an easy way to set it up.

But let’s step back for a second: what are Github pages?

it’s a web space granted to each Github user and project where you can publish anything related to the subject: users might decide to publish their curriculum/resume or contact information while a project might publish a nice looking documentation.

A good set of information is available via a mini site which already guides you through the setup process, so I’m not going to reproduce that here.

Briefly, for a project site, the site contents are going to be hosted withing the project git repository (it does make a lot of sense to me) whitin a dedicated branch gh-pages.

What I wish to share is the set of git commands you can use to setup an existing project to host a clean Github pages setup.

Within the project folder you want to run:

git checkout --orphan gh-pages
git reset
touch .gitignore
git add .gitignore
git commit -m "gh-pages setup"
git push -u --all

You will end up with an almost empty folder (don’t panic, your project is not gone!) apart for the empty .gitignore file.

The project is now displaying what is published on your project’s Github pages, which is nothing at start. You can easily switch between the project contents and the project website by using the git checkout command:

  • git checkout master re-populates your project folder with your project contents
  • git checkout gh-pages brings you back to project website editing

The nice part of the above sequence is the newly created gh-pages branch is not going to share anything with your code branch structure or, if you prefer, master is not a parent for gh-pages!

You can now populate the website with your content using your HTML5 or MarkDown skills, or you can use one of the readily available templates from Github to get a nice looking index.html page to start from.

Also, additional and advanced features are available for multi-page websites via Jekill, but that’s another story.

FlexiPower: the interview

Following the enthusiasm of my previous post, I wish to share an interview a good friend of mine gave to me the latest days of August for his own blog.

The original interview run in Italian, but here I’m posting an English translation: thank you Francesco for pushing me into learning Arduino! 🙂

Zeirus: Hi Roberto. Can you explain with few words what FlexiPower is and which use, us mortals, can do of it?

Roberto: Hi Francesco, I’ll be very glad to do so! FlexiPower is a tool thought for electronic enthusiasts, being newbies or advanced. It is a portable power supply providing two independent channels, both voltage and current controlled. It might seem a niche instrument, but it’s not: anybody playing with an Arduino or a Raspberry Pi, but also those very beyond that phase, know it is an important tool. Usually they are bench instruments, heavyweight, powered by mains e quite expensive, in the order of thousands euro. Normally a newbie would look for cheap Chinese clones, but those have important culprits and might be extremely dangerous.
I wanted to keep costs down in my project, but I didn’t want to sacrifice anything in terms of quality, so I went for an headless instrument, without a screen or any physical user interface, but a remote control via a smartphone and a WiFi connection, with the advantage FlexiPower can be remotely controlled from the other side of the world! Going for a smartphone also allowed me to introduce a feature only the most expensive versions of these tools provide: continous and prolonged logging of current output, and the ability to plot a diagram.


Zeirus: Did you base FlexiPower on some already existing project? If so, what have you specifically added/tweaked to make it “better” than the original?

Roberto: Obviously I hardly copied from another project made by somebody much more experienced and knowledgeable on electronics than I am: Dave Jones, author of a popular electronics channel on YouTube, did publish multiple videos describing, step by step, his own project uSupply. From an end user perspective FlexiPower adds a second channel a completely drops the physical UI, originally consisting of two rotary encoders and an LCD screen. In reality I had to face multiple little and less little problems, many of which I wasn’t aware of until I broke my nose on them.

La schermata di settaggio con presets La schermata del canale #2

Zeirus: How many hours/days have you spent so far developing FlexiPower?

Roberto: To be honest I’m not sure I can quantify it. If you consider I first had to learn how to create such type of instruments… actually I’m not sure I’ve understood all the secrets. After  had to learn the details of the starting project, study each of its components and understand their characteristics. From that point I started to believe it would have been easy, after a few months I undestood how much I was wrong. I don’t think it’s a lie to say I did spend no less than 10 hours a week for the past 18 months working on FlexiPower. Clearly most of the time was during the weekend and holidays, for the greatest joy of my partner!

Zeirus: I can only imagine her Posso solo immaginare la gioia immeasurable joy!🙂
Do you believe your senior experience on the Java programming language has anyhow helped you? 

Roberto: No, I don’t think so, to say the truth. Micro controllers are commonly programmed in C and even the smartphone user interface has been developed as an hybrid application, so based on JavaScript…. I would say Java has little to do with the whole project, but my software developer background has definitely guided me toward the remote interface and, maybe toward a new perspective on those type of tools, with characteristics reserved to more expensive ones.

Zeirus: Which open-source softwares did you use to develop your project? Do you believe they are up to the task or is there still something missing?

Roberto: That’s truly an interesting question because I did try many EDA softwares (CAD dedicated to electronics) for this project, but many were under my expectations: rough, impractical or extremely limited. Then something turned around my opinion: almost a year ago, during the Rome Maker Faire, I met somebody from the company producing the market leader software, Altium. Clearly their top of the line product , you can easily imagine that, is priced comparable to a car, but they had recently released a free version of their software called CircuitMaker. The only real limitation is you have to share your creations.
As a truly convinced supporter of open source I couldn’t avoid a try and I was really impressed by the tool quality: no surprise they are the market leaders. Up to now I believe it’s the best free tool for creating electronic projects, way above the old classic tools like Eagle CAD!


Zeirus: That’s great! It’s a pity CircuitMaker is not – yet – available on non Windows platforms (even if you can actually make it work in Ubuntu via Wine). Anyway, do you believe electronics nowadays is simpler than in the past? Let’s say twenty years ago? If yes, what do you envision for the new twenty years? 

Roberto: Absolutely! Arduino has turned the micro controllers and digital electronics into toy, accessible to practically anybody. Just follow an online tutorial and you’ll learn how to burn a few components and get addicted. I still remember when my older brother was learning PIC micro controllers, spending hours to program them to blink an LED using an UV lamp to erase the chip!

Now you can get the  same results with 5 lines of code, an USB connector and you don’t even have to know the principles of electronics. Sure, after burning to death a few LEDs you might start to learn you need a series resistor, but isn’t a pleasure to see those bright little bastards die into smoke?

Zeirus: With the exclusion of the merciless genocide perpetrated against “those bright little bastards”, would you know consider yourself a true maker, or do you still miss “something” to be one?

Roberto: Everybody decides to build something starting from little or nothing can consider himself a maker, in my opinion. I believe I became a maker when i built my first LED cube, a miniscule 3 x 3 x 3 still sitting on my office desk which I’m really proud of!


Zeirus: What is the tool you still miss in your maker “lab”?

Roberto: I don’t know where to start. To be honest my lab is contained inside 3 drawers of my home desk, including all the electrical components collected so far, the numerous boards and a certain amount of prototypes.

I don’t have much space in my house as I don’t own a garage or a room dedicated to myself only, so anything I use must hidden to sight when not in use (Zeirus’ note: that means hidden to his partner’ eyes! 🙂) . I own a little oscilloscope, with ridiculous characteristics, but adequate to my current needs. A multimeter, pen style soldering iron, a set of tweezers and screwdrivers, a caliper and little more. A tool I am aiming for is a CNC milling machine to quickly realize PCBs for my prototypes…

Zeirus: I know FlexiPower is going to participate as best project of the year on Circuit Maker and the competition will close in a few days! Are you near project completion? What is still missing?

Roberto: In reality it’s Project Of The Summer 2016, a competition closing by the end of August for which I spent a lot of time to refine FlexiPower. The project is at a really good stage, I just sent out an order for the second round of PCBs (10) as the first ones were unusable: I have made some mistakes, it was my very first time… I already have the components to build 4 prototypes of the FlexiPower, even if I believe a couple of tries to realize the next round of improvements.
The software is only in a very alfa status at this stage, but that’s not my top concern as that is my daily bread. I’m more concerned about the PCBs, I hope I didn’t made any other silly mistake this round: I obviously underestimated the complexity in such task and I wasted a lot of time in trial and errors… but I believe I’m there now!

Zeirus: Well, as we say: practice beats theory!😉 … The final question! Be honest: do you believe your project is a first place one?🙂

Roberto: Sincerely I can’t evaluate that, but I threw in all my enthusiasm and energy so that others, more knowledgeable and experienced then me, might consider it worth for the competition.

I would be really praised to receive a recognition for my project, but that’s not the reason why FlexiPower exists. I hope it will become the most forked project, possibly with great contributions from the CircuitMaker community… and it’s in a good shape so far!

Zeirus: Wonderful! Than there’s nothing left other than wishing you the best for the final result!

Roberto: Thanks a million buddy!

Am I a Meta Maker™?

Yesterday has been a special day for me.

It started as any other day of my recent life, with a late alarm after a too short sleep. As usual I had my morning shower and rushed into the office were I spent my day working together with the other members of my team and running meetings with my partners abroad: a day as many others, as I said.

It was quite late when I finally returned home, but I knew my day was not over yet: an electronics project is waiting on my desk, expecting somebody to troubleshoot the issue currently preventing the I2C bus communication.

I have spent countless nights working around this project, with great joy for my partner!

It all started because I wanted something compact to power my electronic projects, an hobby that caught me unarmed a couple of years ago, may be three.

Now I have this splendid (to my eyes) circuit board on my desk: a couple of plastic arms keep it suspended, while few wires depart from it to reach diagnostic interfaces, in an attempt to provide the information I’m seeking for.

In July and August my work on this project got an impressive boost: I decided to enter the CircuitMaker Project of the Summer 2016 contest.


I knew there were many, and much more experienced, people going to participate, but I wanted to be part of the game nonetheless: you need to test you abilities to know where you stand and you can improve.

Obviously, I must admit, I had hopes when I threw myself into the competition: I really wished to win the prize, that precision CNC looked so cool! Not to mention it’s a tool I would definitely wish! But before competition closing I had a look at the top projects and they looked so amazing…


Well, I don’t stand a chance, but it was the opportunity to finish the project! I won already! Now I just have to solve this damn I2C issue…

So, yesterday I received an email…. The email contained a link to a blog post… but my name wasn’t in there. That didn’t surprise me much, I thought

Hey, look how cool are the runner up projects! I wasn’t even aware of that one…

There was also a YouTube video embedded in the post, so to discover my project was among the finalists! (Hey Ben, click on this link, please! smiley-10225)

Really? Did you really took my project into consideration for the final? Is it really so cool?

That was exactly my thinking while I was getting excited, now calling in my partner to join me and share with her the news.


Can you imagine my reaction when we got close to the end just to discover the big suprise? Well, something like…

Can you imagine how good it feels to get a recognition for your hobby, the thing you do just because you like to do it? And suddenly somebody tells you Well done buddy, this is really good!

It is just amazing guys, really amazing!

I wish to say Thanks! to all those who voted my project on the CircuitMaker community: you have been the ones who pushed me into the competition in first place!

Also I wish to Thanks! Dave Jones, the author of the uSupply, the design the FlexiPower is based on: you have thought me, you have inspired me and I know I have just made a few modifications to a great design!

I wish to say Thanks! to you guys at CircuitMaker for your great tool, it really feels great working with it: I finally feel like I have a professional EDA in my hands and the community and support is just great! Keep going lads, you are doing great!

Obviously I wish to say Thanks! to the young pretty lady from Othermachine Co, Danielle Applestone, for selecting FlexiPower as winner: I swear I didn’t bribe her!

Finally, but certainly not least, I wish to say Thanks! to my family and friends, who supported me along the route, with a special mention to Annamaria (my partner) who had to go in bed alone, in the cold winter nights of Central Italy (?!?!), so many times, while I was chasing my maker dreams sitting at my desk…

Thank you!
Thank you so much!


Programming an ATmega328

Ever heard about Barebone Arduino? It consists of trimming down an Arduino to it’s very basic parts and can be really effective in cost reduction.


Tipical Barebone Arduino

Even it might seem the simplest version of an Arduino (actually I wouldn’t be calling it an Arduino any more) we can go even further and drop the external crystal in favor of the internal (yes, there is one) oscillator: that is now just a plain ATmega328:


Thanks to pighixxx for his beautiful pinout diagrams!

To program an ATmega328 or, for what matters, many other MCUs, you can use an USBasp, an hardware device providing direct access to the MCU via ICSP, aka a programmer. Installing the USBasp drivers under Windows 10 has been time consuming, but luckily a very simple solution does exist.

I’m not going into the details of how you connect the USBasp to the ATmega328 as this is information widely available on the web and the first link is quite comprehensive in this regards. So the remaining part is, obviously, software!

There is only one option in my mind when it comes down to programming microcontrollers: Sloeber (formerly known as Arduino Eclipse Plugin). The latest release is just great and not only because I did personally contribute a few bits here and there, but because the whole thing is just a leap step forward in MCU development compared to Arduino IDE.

Programming a bare ATmega328 though has provided some challenges I’m here to describe for those who might encounter the same issues.

Installing the tools

With Sloeber it’s quite easy to install support for new boards, even those which are not built-in or, if you prefer, third-party.

Just open Window > Preferences > Arduino > Locations, you’ll find a link in the bottom part of the settings page, click on it and search the web page for the board or board set you’d like to install. I was looking for “barebone” and that is what I added into my list of locations: (if you want to shortcut and avoid the issues I’ve faced, an alternative URL is available at the very bottom of this article).


Then switch to the Platforms and Boards section to select and obtain the definitions to build for a bare ATmega328: obviously I’m going for the latest available version.


After a few seconds I got my Sloeber ready for compiling what would be a normal Arduino project but targeted at a barebone Arduino!

build config

My choice was to create a custom build configuration, but that’s totally optional.

Filling the gaps

I encountered a few compilation problems though, which I was able to overcome with some support.

Making the long story short I had to modify the JSON file associate to the Barebones ATmega Chips in order to provide some missing information:

  • the tools section, originally consisting of an empty array, should contain the references to the two tools used by the package, avr-gcc and avrdude
  • the toolDependencies section needs to be updated in order to match the tool versions now being linked

I’ve prepared a fixed JSON package file available from

Also I had to copy the programmers.txt from arduinoPlugin\packages\arduino\hardware\avr\1.6.13 to arduinoPlugin\packages\atmega\hardware\avr\1.3.0 in order to make the USBasp protocol available with the new boards file.

Setting the fuses

When you buy a plain ATmega328 micro controller you are more than probably going to get the chip configured to the factory settings, meaning it will run at a 1MHz with it’s internal oscillator. That’s obviously a very conservative setting on which you have control, along with some other settings, via the chip fuses.

If you never had to deal with chip fuses before and the AVR ones in particular, you might want to read at least an introductory explanation  before going to change any of them.
WARNING: an erroneous setting of the chip fuses can turn your micro controller into a desk decoration, don’t blame me if that occurs to you!

I want the chip to run at 8MHz which requires just one bit to be changed, but I’m taking the opportunity to also tweak other parts of the settings and I’m going to use a nice AVR Fuses Calculator web application to do so:

  • low fuse 0xE2 means “use the internal 8MHz clock source and run at full speed
  • high fuse 0xD6 means “don’t clear the EEPROM each time and don’t reserve any space for a bootloader
  • extended fuse 0x07 means “don’t auto reset on min voltage

To do so I’m using the avrdude tool, which I already got installed automatically by Sloeber.

To quickly get to avrdude look at the last command printed by Sloeber into the upload console when you try to upload any firmware/sketch to the micro: it should look like the following

Launching X:\Sloeber\arduinoPlugin\tools\arduino\avrdude\6.0.1-arduino5/bin/avrdude -CX:\Sloeber\arduinoPlugin\tools\arduino\avrdude\6.0.1-arduino5/etc/avrdude.conf -patmega328p -cusbasp -Pusb -Uflash:w:D:\Projects\.cpp\Serial/Release/Serial.hex:i

The bold part is what you want to copy past into a command prompt and then add the missing bits:

X:\Sloeber\arduinoPlugin\tools\arduino\avrdude\6.0.1-arduino5/bin/avrdude -CX:\Sloeber\arduinoPlugin\tools\arduino\avrdude\6.0.1-arduino5/etc/avrdude.conf -patmega328p -c usbasp -U lfuse:w:0xE2:m -U hfuse:w:0xD6:m -U efuse:w:0x07:m

If all goes well you should get a nice and reassuring confirmation message like the following:

avrdude: safemode: Fuses OK (H:07, E:D6, L:E2)
avrdude done. Thank you.

Upload a firmware

Once you have all of the above in place, uploading a firmware to your micro controller is not going to be different from doing the same on any of your Arduino boards: hit the upload button, let Sloeber compile your code and enjoy your cheap and very professional setup!

USBasp & Windows 10


If you have an USBasp programmer and a recent Windows machine you have more than probably stumbled into a disappointing message, either from Arduino IDE or Sloeber:

avrdude: error: could not find USB device with vid=0x16c0 pid=0x5dc vendor='' product='USBasp'

I believe I’ve spent at least a couple of hours searching for a solution which would not require downloading some weird drivers from an unknown source.

Almost all forum threads I’ve been reading were describing a clunky process which involved rebooting the OS and disabling the driver signature verification to permit the installation of a driver you could download from Mediafire or attached to the posts… not something I’m really willing to do.

Making the long story short you just download Zadiq (a well known, reliable and open source software) and install the libusbK driver for your USBasp device: that’s it!


Markdown with Yada Wiki and Jetpack

In the office we have recently decide to migrate our team wiki to WordPress and Yada Wiki has been selected.

The team is also quite comfortable with Markdown, even if not everybody is ready to adopt it as the main editor, so I struggled a bit to find a solution, until I stumbled upon Jetpack.

I installed Jetpack directly from the WordPress admin console (which I just love!), but I had to connect to the server console to force Jetpack into developer mode, which is required if your server isn’t going to be publicly accessible.
To do so you need to open your wp-config.php, search for define('WP_DEBUG', false); and add the following line

add_filter( 'jetpack_development_mode', '__return_true' );

That brings you one step forward, but after enabling the Markdown feature in the Jetpack installation page you will be able to use Markdown in pages and posts only: your wiki pages will not be affected. That’s because Yada Wiki uses it’s own custom content type to distinguish wiki pages from other contents, which is a good thing.
So you need to extend the Markdown support to this additional content type, which is easily achievable adding the following lines at the very end of the functions.php file of your theme of choice:

add_action('init', 'my_custom_init');
function my_custom_init() {
    add_post_type_support( 'yada_wiki', 'wpcom-markdown' );

Now your wiki editors can decide to use the WYSIWYG editor or switch to the text editor and start typing their contents in Markdown syntax and preview their edits by just hitting the Preview button.