Arduino + Modules = FEZ Medusa

Arduino Technology
Arduino + Modules = FEZ Medusa

FEZ Medusa

There’s no denying the fact that everyone loves the ever popular Arduino.  However, the “shield” approach used by Arduino has its limitations and those of us that are also fans of the Gadgeteer prototyping platform know that there’s a better solution – modules.  Finally, it looks like there will be a module-based Arduino derivative that will allow the use of Gadgeteer modules.

A Kickstarter for the FEZ Medusa launched last week by GHI Electronics.  The Medusa is a family of mainboards & a shield that give Gadgeteer compatible sockets to the Arduino world.  The use of sockets & modules give Arduino projects much more flexibility than is currently available with shields and adds several new sources of modules from several companies to Arduino developers.  Also, if you have a collection of Gadgeteer modules already then its very likely that you’ll be able to use many of them with the FEZ Medusa.

I had a chance to speak with Gus Issa, President of GHI Electronics, about the FEZ Medusa Kickstarter and this is what he had to say.

Is this GHI’s first Arduino product offering?

We do offer boards with the standard Arduino pinout and shield concept but these boards are not programmed using the Arduino IDE. While these boards give you a more beefy micro and more libraries, they must be programmed using VisualStudio on Windows.  This is where the all new FEZ Medusa comes in; to give the user a true Arduino experience using any operating system.

As a big fan of both Arduino & Gadgeteer (which share the same module design), I’m especially excited to see the two come together.  For the large base of Arduino users out there that have not tried Gadgeteer, what would you say is the number one advantage these users will receive by using a module based mainboard such as the FEZ Medusa?

Flexibility and reusability. Whether you are upgrading to a powerful mainboard (the board with the processor) or downgrading to a smaller mainboard, you are reusing the same modules.  And if you wanted to change a module, the rest of your design can stay the same.  Like if you want to use a 16x relay board instead of a single relay.  You will also be able to customize the look of your end design in a 3D printed enclosure or laser cut acrylic, thanks to the flexibility that the cables provide.

What is the advantage of using modules and cables instead of shields?

Shields are great but they are not exactly designed to work on other systems.  Any board designed to use these shields will have to have the exact footprint and pinout as Arduino. What if you want a smaller board?  Well Arduino offers a smaller mini version but that does not work with shields. Basically, in most cases, when a user changes their board that hosts the micro they have to throw away the shields they have or they have to wire them manually which is not an easy process. The modules are designed to be 100% micro and mainboard independent.  For example, our Music Module hosts an MP3 decoder chip that uses SPI bus. The chip is added on a small board with a socket labeled “S”. There is a predefined standard on how SPI connects to the socket showing where SCK, MOSI, MISO and GPIOs are connected. This module will work with any mainboard that has socket type “S” as the mainboard will have the SPI bus from the micro connected to a socket, which is labeled “S”.

Another problem with shields is that they share the same pins. This means that the user would have to make sure the shields they are about to use are not using the same pins. This is not a problem with modules since you can think of each socket on the mainboard as a shield.  But what happens when you need more sockets? This where you can use a larger mainboard with more sockets but of course, keep using the exact same modules.  Even if you need more processing power, you can get a 400Mhz mainboard today that will work with the same modules. The 400Mhz board is not Arduino but will still work with the same modules.

Finally, creating enclosures for stacked shields is difficult.  When one or more shields are stacked they become very bulky with the connectors found in a difficult location to create enclosures.  With modules, you have wires of different lengths to place the modules anywhere you like inside a laser cut acrylic or 3D printed enclosure. Designing enclosures is made easier as we provide 3D models for all modules and mainboards.  Adding more, the mounting holes on all modules and mainboards are 3.2mm in diameter and are spaced on a 5mm grid. You can even create mounting plates.  You can see examples of this in our “community showcase” & “community creations” pages on our website.

What are the disadvantages of using modules and cables instead of shields?

It maybe a tad difficult to move projects around if they are not mounted.  We always recommend enclosures, mounting plates or something as easy as standoffs to mount the modules to each other.

Most of the people that are anti-Gadgeteer complain about the requirement to use a Microsoft OS & dev tools.  Does Microsoft have any role in this project?  Is there any requirement to use Windows?

You are using the Arduino IDE, period!  Anywhere that the Arduino IDE works, FEZ Medusa works.  If fact, the design is so close to the Arduino UNO that we have an LED on the exact same pin.  If you open the LED blink example for Arduino UNO and load it on FEZ Medusa, the onboard LED will simply blink.

Why would someone want to build a project based on modules instead of creating a shield to hold all the components?  Wouldn’t a single shield be cheaper?

When creating a shield, you are going to use it on Arduino only, not on Raspberry Pi or Beaglebone, for example.  When creating a module with the Gadgeteer standard pinout, you are making something that will be accessible to everyone, no matter what system they have.  If their system has the standard sockets, then they can just plug it in.  If they don’t, then they can wire it in.  At least the wiring in this case is on one socket, which has 3 power pins [+5V, 3V3, GND] and only 7 signal pins.

How many compatible modules are there available for Medusa?  I see a nice list shown in the Kickstarter but I see close to a hundred on your site listed as Gadgeteer modules.  Will all of these work with Medusa once drivers are developed?  Do you expect a community effort to help in this effort?

There are over 100 modules and the list is growing.  95% of these modules will work with FEZ Medusa but some will not because of the limitation of the micro being used.  For example, we have a 7” display with a capacitive touch screen.  This display requires a micro with a display controller.  Those pins are mapped to sockets “R”, “G” and “B”, which you will not find on FEZ Medusa.  Another option is our WiFi RS21 which requires some large libraries to work.  It won’t work but we have two other WiFi options that will.

GHI has quite a collection of modules available on its site.  Is the socket design an open standard and are there other companies producing these modules according to this standard?

Yes there is a standard on socket types and how the pins will connect to each type.  Socket “U” is UART, which is a serial interface, and the standard shows where the RX and TX pins go.  This standard started at Microsoft research in UK and today it is open for everyone to use.  There are multiple companies and makers creating more modules, some examples include: ​

How difficult is it to port an existing Arduino driver to work with a module?

The exact same pins found on Arduino-compatible mainboards are the same pins found on the FEZ Medusa Mini and also on the first three sockets on the FEZ Medusa S12 and the Shield. Same micro, same pins and therefore this is nothing to port. However, we recommend you take advantage of the libraries we provide for socket mapping. This way, your created driver will work fine whether you plug your module in socket 2 or socket 5. However, you are not required to use any of these libraries.

As an Arduino derivative, there’s no requirement for GHI to contribute back to the Arduino core.  Will GHI be contributing back to the Arduino core in any way either monetarily or in another way?

On the software side, we have thousands of lines of driver code that is being all posted on a Git repository [as open source].  On the hardware side, all board designs are provided in EAGLE format.  As for the Arduino IDE itself, we have couple improvements in mind that we like to work on in the near future and we will be contributing everything back.

The Arduino Yun recently launched with built-in WiFi as a way of helping move along IoT projects at a faster pace.  In my opinion, the biggest hurdle for achieving the IoT is reducing the price of going wireless.   I don’t think the Yun does enough in this regard.  Does GHI have a solution with the Medusa that will help get us there faster?

We are working with the community on completing a low cost WiFi CC3000 Module. Once completed, you can plug that into a $10 FEZ Medusa Mini. Of course, if we see enough interest from the community, we could create a FEZ Medusa with built in WiFi. Most products created by GHI Electronics are community driven. And by having our own engineering and manufacturing, right in our facility in Michigan, we can turn out products fairly quickly.

As we are talking, you are less than $1800 from your funding goal after less than two days.  You’ve set some really nice stretch goals including the Lynx board which would work with almost any USB capable computer.  Why should people interested in Arduino care about this?

Arduino will always have its place and need.  How could we create a $10 mainboard if it wasn’t for the near $1 micro?  Developers will always have different needs and requirements.  We feel that by pairing an Arduino-compatible processor board with FEZ Lynx, an interface board allowing access to any device with USB host capabilities like Raspberry Pi, Beaglebone, Smartphones, Tablets and PCs running Android or Windows, we will be creating a complete ecosystem that will bridge the gap between developers and their needs.

Earlier this year, you had another successful Kickstarter, the FEZ GameO.  Did you have any problems executing and delivering those devices?  Were there any lessons learned from that Kickstarter that you applied to this one?

We have been engineering and manufacturing for many years.  This experience with the help of some insiders in our community allows us to completely test the product before it ships.  And by having our own production line, we can get products out on time, while keeping top quality standards.  Of course, problems have occurred in the past but throughout the years we learned how to solve them.  We take pride in our customer’s satisfaction and near zero returns.

Thank you, Gus.


I’ve received an early preview shipment of the FEZ Medusa boards and I’ll be doing a full review and reporting back soon.  Yes, I am a backer of this project.  As a long time fan of both Arduino and the modular Gadgeteer system, I’m very excited about what it could mean to both platforms if this Kickstarter were a huge success.

If you have questions or concerns about the FEZ Medusa, please take them to the comments section of the Kickstarter and someone from GHI will address them.

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I'm a software engineer by day and maker by night. Most of my making revolves around woodworking, electronics, and the combination of the two. I'm also the founder & president of NashMicro - the Nashville Microcontrollers users' group and the father of three future makers. Follow me on Twitter as @ianlee74 or for the most recent news on everything Gadgeteer, follow @gadgeteerin.

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