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Sunday, November 04, 2018

HVDN [reset] = Is the "Feather" better?

Embedded computing and open hardware in the form of Raspberry Pi, Arduino and a few others have propelled creativity in the maker, electronics hobbyist, STEM education and amateur radio communities in recent years.

A new format standard called Feather has recently come to market and is very exciting, so lets find out why.

Embedded computing you say?

Since 2012, there have been over 19 million Raspberry Pi sold when combining all the different (and improved) versions sold over the years.

Perhaps the biggest competitor to the Raspberry Pi has been the genuine Arduino family of micro-controller boards with an estimated few million shipped.

Both "embedded computing" ecosystems have spawned various forked versions that illustrate the success these two standards have demonstrated both for hardware and software compatibility.

HVDN [reset] is a sub-series of content that compares  different enabling or disruptive innovations relevant to the  maker, electronics hobbyist and amateur radio community.
HVDN [reset] is a sub-series of content that compares
different enabling or disruptive innovations relevant to the
maker, electronics hobbyist and amateur radio community.

One reason that has made both devices popular for add-on device or "hat" accessory development has been standard sizes and pin or GPIO configurations.

This has helped developers create exciting applications quickly & reliably

A new standard called "Feather" has arrived recently and promoted by Adafruit and Sparkfun, both known for providing a range of original add-on products to build even better Raspberry Pi and Arduino based projects.

18 different Feather based products using standard sizing and connections

The [reset] moment

Thanks to Limor Fried and her team at Adafruit along with a number of different vendors like Particle, the new Feather and related terms such as "Feather Board" and "Feather Wing" are poised for a lot of success.

This HVDN [reset] article will explore the "Feather" open hardware ecosystem in  comparison to Raspberry Pi and how it simplified development of our latest project by standardizing on this new small form factor wireless enabled embedded computing standard.

Different sizes of Pi for all appetites

Let's look at how the size of the most well known and current Raspberry Pi offerings look next to each other.

Pictured from top left clockwise are the Pi Compute 3 Module,
Raspberry Pi 3 and Raspberry Pi W Zero

Raspberry Pi has been chosen by HVDN to compare against the Feather format because they all offer wireless connectivity.

Arduino has too many variants to compare that have a similar size to Feather but do not offer wireless connectivity. ESP32 and ESP8266 boards have too many versions.

A major benefit with many of the smaller Feather based products
compared to the slightly larger Raspberry Pi Zero is built
in battery charging, power options and connectivity options.

Arduino versions such as the Nano, Micro, and Lilypad along with the Adafruit Trinket are left out of this review since they lack wireless connectivity.

Plucking Feathers

Specifications help drive standards and adoption, so Adafruit has everything documented on its website to make development easy for most everyone.

Standard dimensions of the Feather help
create easy product development and compatibility
Key Feather Physical Dimensions:
  • The 'classic' Feather and Wing size is 0.9" x 2.0" with 0.1" holes at each corner.   
  • There is one 16-pin breakout strip on the bottom side, centered 1.0" from the left edge.  
  • There is one 12-pin breakout strip on the top side, 1.2" from the left side.  
  • The spacing between the two strips is 0.8"  
  • Don't change the GPIO spacing or location, or you will not maintain compatibility with Wings! 
Key Feather "In/Out" Specifications

Using the Particle.IO "Argon" product as the example, here are the connection details copied from the super helpful datasheet.  Many of the elements found in certain Particle products were even part of the attendee badge at this years Open Hardware Summit to show example of an embedded application in the real world.

So, what is the project?

In 2017  HVDN started to develop a modern field strength meter that has remote sense and analytic capability as featured in the Field Strength Meter Monday series.

After working out the actual sensor part of the project and offering for sale a limited run of stand-alone sensors, we then set to work to redesign the RF signal strength sensor unit to fit as a "hat" onto a popular embedded computing board.

The initial plan was to use the Arduino Nano because it was low cost and easy to program but was soon abandoned because certain versions of it used non-standard USB drivers to update or interface to the device.

A later version looked at standardizing around the STM32 based ESP32 and ESP8266 based embedded computing devices because they both offered integrated battery charging and wireless functionality. They also used the very flexible microPython programming language.

WEMOS ESP32 based Wi-Fi/BLE
4MB microPython IoT device
Quality and version control of these different ESP32 or ESP8266 based boards proved hard to develop easily replicated results around, but working prototypes showed the proof of concept was sound and could be improved upon.
Looking at Feather based options again seemed ideal due to a price drop and additional features. 
It was decided to build this project around the Particle Argon (Wi-Fi + Mesh)  and Xenon boards (BLE + Mesh), with potential support for the Boron (LTE + BLE + Mesh) board at a much later date.

Making projects simple with Feather

The Adafruit Feather based options helped simplify our project design and also allowed even more features to be added!

Future articles will cover microPython coding basics, computer-aided circuit design and fun applications for this exciting project.

Here is the HVDN-FS1....

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