Arduino-Based Tube Stereo Preamp Project

If you happen to be electrical engineer as well as an audiophile, you’re in luck. With an Arduino, some typical components, and a little knowhow, you can build DIY tube stereo preamplifier design.

Shannon Parks—owner of Mahomet, IL-based Parks Audio—designed his “Budgie” preamp after reading an article about Arduino while he was thinking about refurbishing a classic Dynaco PAS-3.

Budgie preamp (Source: S. Parks)

Budgie preamp (Source: S. Parks)

In a recent audioXpress article about the project, Parks noted:

Over the last 10 years, I have built many tube power amplifiers but I had never built a tube preamplifier. The source switching seemed particularly daunting. A friend recommended that I refurbish a classic Dynaco PAS-3 which has been a popular choice with many upgrade kit suppliers. Unfortunately, the main part of these older designs is a clumsy rotary selector switch, not to mention the noisy potentiometers and slide switches. In the 1980s, commercial stereo preamplifiers started using IC microcontrollers that permitted cleaner designs with push-button control, relays for signal switching, and a wireless remote. While reading an article about the Arduino last year, I realized these modern features could easily be incorporated into a DIY preamplifier design.

All the circuits are on one custom PCB along with the power supply and microcontroller (Source: S. Parks)

All the circuits are on one custom PCB along with the power supply and microcontroller (Source: S. Parks)

Parks said the Arduino made sense for a few key reasons:

I found these features were incredibly useful:

  • A bank of relays could switch between the four stereo inputs as well as control mute, standby, gain, and bass boost settings.
  • A red power LED could use PWM to indicate if the preamplifier is muted or in standby.
  • An IR receiver with a remote could control a motor-driven volume potentiometer, change the source input selection, and turn the unit on/off. Any IR remote could be used with a code learning mode.
  • A backlit display could easily show all the settings at a glance.
  • Momentary push buttons could select the input device, bass boost, gain, and mute settings.
  • Instead of using several Arduino shields wired to an Arduino board, all the circuits could fit on one custom PCB along with the power supply and the microcontroller.

Parks used an Arduino Nano, which 0.73” × 1.70”. “The tiny Nano can be embedded using a 32-pin dual in-line package (DIP) socket, which cleans up the design. It can be programmed in-circuit and be removed and easily replaced,” he noted.

Parks used an Arduino Nano for the preamp project (Source: S. Parks)

Parks used an Arduino Nano for the preamp project (Source: S. Parks)

Parks described the shift register circuit:

The Budgie preamplifier uses a serial-in, parallel-out (SIPO) shift register to drive a bank of relays ….

A SIPO shift register is used to drive a bank of relays (Source: S. Parks)

A SIPO shift register is used to drive a bank of relays (Source: S. Parks)

Only four Arduino digital outputs—enable, clock, latch, and data—are needed to control eight DPDT relays. These correspond to the four outputs labeled D3, D4, D5, and D7 s …. The Texas Instruments TPIC6C595 shift register used in this project has heavy-duty field-effect transistor (FET) outputs that can handle voltages higher than logic levels. This is necessary for operating the 24-V relays. It also acts as a protective buffer between the Arduino and the relays.

Here you see the how to set up the Arduino Nano, LCD, power supply, push button , IR and motor control circuits (Source: S. Parks)

Here you see the how to set up the Arduino Nano, LCD, power supply, push button , IR and motor control circuits (Source: S. Parks)

As for the audio circuit, Parks explained:

The 12B4 triode was originally designed to be used in televisions as a vertical deflection amplifier. New-old-stock (NOS) 12B4s still exist. They can be purchased from most US tube resellers. However, a European equivalent doesn’t exist. The 12B4 works well in preamplifiers as a one-tube solution, having both high input impedance and low output impedance, without need for an output transformer. An audio circuit can then be distilled down to a simple circuit with few parts consisting of a volume potentiometer and a grounded cathode gain stage.
The 12B4 has about 23-dB gain, which is more than is needed. This extra gain is used as feedback to the grid, in what is often referred to as an anode follower circuit. The noise, distortion, and output impedance are reduced (see Figure 3). Using relays controlled by the Arduino enables switching between two feedback amounts for adjustable gain. For this preamplifier, I chose 0- and 6-dB overall gain. A second relay enables a bass boost with a series capacitor.
You only need a lightweight 15-to-20-V plate voltage to operate the 12B4s at 5 mA. Linearity is very good due to the small signal levels involved, as rarely will the output be greater than 2 VPP. A constant current source (CCS) active load is used with the 12B4s instead of a traditional plate resistor. This maximizes the possible output voltage swing before clipping. For example, a 12B4 biased at 5-mA plate current with a 20-kΩ plate resistor would drop 100 V and would then require a 120-V supply voltage or higher. Conversely, the CCS will only drop about 2 V. Its naturally high impedance also improves the tube’s gain and linearity while providing high levels of power supply noise rejection.

This article first appeared in Circuit Cellar’s sister publication, audioXpress (July 2014).



DIY Arduino-Based ECG System

Cornell University students Sean Hubber and Crystal Lu built an Arduino-based electrocardiography (ECG) system that enables them to view a heart’s waveform on a mini TV. The basic idea is straightforward: an Arduino Due converts a heartbeat waveform to an NTSC signal.

Here you can see the system in action. The top line (green) has a 1-s time base. The bottom line (yellow) has a 5-s time base. (Source: Hubber & Lu)

Here you can see the system in action. The top line (green) has a 1-s time base. The bottom line (yellow) has a 5-s
time base. (Source: Hubber & Lu)

In their article, “Hands-On Electrocardiography,” Hubber and Lu write:

We used the Arduino Due to convert the heartbeat waveform to an NTSC signal that could be used by a mini-TV. The Arduino Due continuously sampled the input provided by the voltage limiter at 240 sps. Similar to MATLAB, the vectorized signal was shifted left to make room at the end for the most recent sample. This provided a continuous real-time display of the incoming signal. Each frame outputted to the mini-TV contains two waveforms. One has a 1-s screen width and the other has a 5-s screen width. This enables the user to see a standard version (5 s) and a more zoomed in version (1 s). Each frame also contains an integer representing the program’s elapsed time. This code was produced by Cornell University professor Bruce Land.

As you can see in the nearby block diagram, Hubber and Lu’s ECG system comprises a circuit, an Arduino board, a TV display, MATLAB programming language, and a voltage limiter.

The system's block diagram (Circuit Cellar 289, 2014)

The system’s block diagram (Circuit Cellar 289, 2014)

The system’s main circuit is “separated into several stages to ensure that retrieving the signal would be user-safe and that sufficient amplification could be made to produce a readable ECG signal,” Hubber and Lu noted.

The first stage is the conditioning stage, which ensures user safety through DC isolation by initially connecting the dry electrode signals directly to capacitors and resistors. The capacitors help with DC isolation and provide a DC offset correction while the resistors limit the current passing through. This input-conditioning stage is followed by amplification and filtering that yields an output with a high signal-to-noise ratio (SNR). After the circuit block, the signal is used by MATLAB and voltage limiter blocks. Directly after DC isolation, the signal is sent into a Texas Instruments INA116 differential amplifier and, with a 1-kΩ RG value, an initial gain of 51 is obtained. The INA116 has a low bias current, which permits the high-impedance signal source. The differential amplifier also utilizes a feedback loop, which prevents it from saturating.

Following the differentiation stage, the signal is passed through multiple filters and receives additional amplification. The first is a low-pass filter with an approximately 16-Hz cutoff frequency. This filter is primarily used to eliminate 60-Hz noise. The second filter is a high-pass filter with an approximately 0.5-Hz cutoff frequency. This filter is mostly used to eliminate DC offset. The total amplification at this stage is 10. Since the noise was significantly reduced and the SNR was large, this amplification produced a very strong and clear signal. With these stages done, the signal was then strong enough to be digitally analyzed. The signal could then travel to both the MATLAB and voltage limiter blocks.

Hubber and Lu’s article was published in Circuit Cellar 289, 2014. Get it now!

24-Channel Digital I/O Interface for Arduino & Compatibles

SCIDYNE Corp. recently expanded its product line by developing a digital I/O interface for Arduino hardware. The DIO24-ARD makes it easy to connect to solid-state I/O racks, switches, relays, LEDs, and many other commonly used peripheral devices. Target applications include industrial control systems, robotics, IoT, security, and education.Scidyne

The board provides 24 nonisolated I/O channels across three 8-bit ports. Each channel’s direction can be individually configured as either an Input or Output using standard SPI library functions. Outputs are capable of sinking 85 mA at 5 V. External devices attach by means of a 50 position ribbon-cable style header.

The DIO24-ARD features stack-through connectors with long-leads allowing systems to be built around multiple Arduino shields. It costs $38.

[Source: SCIDYNE Corp.]

Q&A with Arduino-Based Skube Codesigner

The Arduino-based Skube

The Arduino-based Skube

Andrew Spitz is a Copenhagen, Denmark-based sound designer, interaction designer, and programmer. Among his various innovative projects is the Arduino-based Skube music player, which is an innovative design that enables users to find and share music.

Spitz worked on the design with Andrew Nip, Ruben van der Vleuten, and Malthe Borch. Check out the video to see the Skube in action. On his blog, Spitz writes: “It is a fully working prototype through the combination of using ArduinoMax/MSP and an XBee wireless network. We access the API to populate the Skube with tracks and scrobble, and using their algorithms to find similar music when in Discover mode.”

Skube – A & Spotify Radio from Andrew Nip on Vimeo.

The following is an abridged  version of an interview that appears in the December 2012 issue of audioXpress magazine, a sister publication of Circuit Cellar magazine..

SHANNON BECKER: Tell us a little about your background and where you live.

Andrew Spitz: I’m half French, half South African. I grew up in France, but my parents are South African so when I was 17, I moved to South Africa. Last year, I decided to go back to school, and I’m now based in Copenhagen, Denmark where I’m earning a master’s degree at the Copenhagen Institute of Interaction Design (CID).

SHANNON: How did you become interested in sound design? Tell us about some of your initial projects.

Andrew: From the age of 16, I was a skydiving cameraman and I was obsessed with filming. So when it was time to do my undergraduate work, I decided to study film. I went to film school thinking that I would be doing cinematography, but I’m color blind and it turned out to be a bigger problem than I had hoped. At the same time, we had a lecturer in sound design named Jahn Beukes who was incredibly inspiring, and I discovered a passion for sound that has stayed with me.

Shannon: What do your interaction design studies at CIID entail? What do you plan to do with the additional education?

Andrew: CIID is focused on a user-centered approach to design, which involves finding intuitive solutions for products, software, and services using mostly technology as our medium. What this means in reality is that we spend a lot of time playing, hacking, prototyping, and basically building interactive things and experiences of some sort.

I’ve really committed to the shift from sound design to interaction design and it’s now my main focus. That said, I feel like I look at design from the lens of a sound designer as this is my background and what has formed me. Many designers around me are very visual, and I feel like my background gives me not only a different approach to the work but also enables me to see opportunities using sound as the catalyst for interactive experiences. Lots of my recent projects have been set in the intersection among technology, sound, and people.

SHANNON: You have worked as a sound effects recordist and editor, location recordist and sound designer for commercials, feature films, and documentaries. Tell us about some of these experiences?

ANDREW: I love all aspects of sound for different reasons. Because I do a lot of things and don’t focus on one, I end up having more of a general set of skills than going deep with one—this fits my personality very well. By doing different jobs within sound, I was able to have lots of different experiences, which I loved! nLocation recording enabled me to see really interesting things—from blowing up armored vehicles with rocket-propelled grenades (RPGs) to interviewing famous artists and presidents. And, documentaries enabled me to travel to amazing places such as Rwanda, Liberia, Mexico, and Nigeria. As a sound effects recordist on Jock of the Bushvelt, a 3-D animation, I recorded animals such as lions, baboons, and leopards in the South African bush. With Bakgat 2, I spent my time recording and editing rugby sounds to create a sound effects library. This time in my life has been a huge highlight, but I couldn’t see myself doing this forever. I love technology and design, which is why I made the move...

SHANNON: Where did the idea for Skube originate?

Andrew: Skube came out of the Tangible User Interface (TUI) class at CIID where we were tasked to rethink audio in the home context. So understanding how and where people share music was the jumping-off point for creating Skube.

We realized that as we move more toward a digital and online music listening experience, current portable music players are not adapted for this environment. Sharing mSkube Videousic in communal spaces is neither convenient nor easy, especially when we all have such different taste in music.

The result of our exploration was Skube. It is a music player that enables you to discover and share music and facilitates the decision process of picking tracks when in a communal setting.

audioXpress is an Elektor International Media publication.

Arduino USB Host Shield

The Arduino USB Host Shield allows you to connect a USB device to your Arduino board. The Arduino USB Host Shield is based on the MAX3421E, which is a USB peripheral/host controller containing the digital logic and analog circuitry necessary to implement a full-speed USB peripheral or a full-/low-speed host compliant to USB specification rev 2.0.ArduinoHostshield

The shield is TinkerKit compatible, which means you can quickly create projects by plugging TinkerKit modules onto the board. The following device classes are supported by the shield:

  • HID devices: keyboards, mice, joysticks, etc.
  • Game controllers: Sony PS3, Nintendo Wii, Xbox360
  • USB to serial converters: FTDI, PL-2303, ACM, as well as certain cell phones and GPS receivers
  • ADK-capable Android phones and tables
  • Digital cameras: Canon EOS, Powershot, Nikon DSLRs and P&S, as well as generic PTP
  • Mass storage devices: USB sticks, memory card readers, external hard drives, etc.
  • Bluetooth dongles

For information on using the shield with the Android OS, refer to Google’s ADK documentation. Arduino communicates with the MAX3421E using the SPI bus (through the ICSP header). This is on digital pins 10, 11, 12, and 13 on the Uno and pins 10, 50, 51, and 52 on the Mega. On both boards, pin 10 is used to select the MAX3421E.

[Source: Arduino website via Elektor]

Nesit (Meriden, CT, USA)

NESIT wants to create, educate, and foster learning in the fields of various technological and other disciplines. They reap the benefits of productivity through volunteer collaboration.

Location 290 Pratt St., Meriden CT 06450
Members 30

Read about what Vice President Will Genovese has to say about NESIT.
Tell us about your meeting space!

NESIT meets in a 4000 square feet office that takes place in The Meriden Enterprise Center. A large office and manufacturing building that is home to over 60 businesses.

What tools do you have in your space? 

Soldering stations, oscilloscope, 3-D printer, woodshop, cnc, and a data center.

Are there any tools your group really wants or needs?

A lasercutter would be a nice addition to our arsenal.

What sort of embedded tech does your Hackerspace work with?

We work with PIC, Arduino, and Raspberry Pi, and many more.
In fact one of our recent projects was a DIY PIC Programmer.

Can you tell us about some of your group’s recent tech projects?


One of the group’s first tech projects was the “MAME,” a full-size gaming arcade. The project was going well until there was a break in at the location and they lost some equipment; the MAME was put on the backburner.  After they moved to their new location and gained a new member, an art teacher named John, the project garnered interest again. He came up with the design for it. Afterwords it was painted, they got a coin mechanism, speakers were hooked up, and the software was installed and configured. IT was finally finished.

Click here if you want to check it out.

What’s the craziest project you’ve completed?

At the moment we have not yet completed projects I would categorize as “crazy.”

Read more about NESIT on their website. 

Show us your hackerspace! Tell us about your group! Where does your group design, hack, create, program, debug, and innovate? Do you work in a 20′ × 20′ space in an old warehouse? Do you share a small space in a university lab? Do you meet at a local coffee shop or bar? What sort of electronics projects do you work on? Submit your hackerspace and we might feature you on our website!

Engineering Consultant and Roboticist

Eric Forkosh starting building his first robot when he was a teenager and has been designing ever since. This NYC-based electrical engineer’s projects include everything from dancing robots to remote monitoring devices to cellular module boards to analog signals—Nan Price, Associate Editor

NAN: Tell us about your start-up company, Narobo.


Eric Forkosh

ERIC: Narobo is essentially the company through which I do all my consulting work. I’ve built everything from dancing robots to cellular field equipment. Most recently I’ve been working with some farmers in the Midwest on remote monitoring. We monitor a lot of different things remotely, and I’ve helped develop an online portal and an app. The most interesting feature of our system is that we have a custom tablet rig that can interface directly to the electronics over just the USB connection. We use Google’s Android software development kit to pull that off.

ERIC: The DroneCell was my second official product released, the first being the Roboduino. The Roboduino was relatively simple; it was just a modified Arduino that made building robots easy. We used to sell it online at for a little while, and there was always a trickle of sales, but it was never a huge success. I still get a kick out of seeing Roboduino in projects online, it’s always nice to see people appreciating my work.


The DroneCell is a cellular module board that communicates with devices with TTL UARTs.

The DroneCell is the other product of mine, and my personal favorite. It’s a cellular module board geared toward the hobbyist. A few years ago, if you wanted to add cellular functionality to your system you had to do a custom PCB for it. You had to deal with really low voltage levels, very high peak power draws, and hard-to-read pins. DroneCell solved the problem and made it very easy to interface to hobbyist systems such as the Arduino. Putting on proper power regulation was easy, but my biggest design challenge was how to handle the very low voltage levels. In the end, I put together a very clever voltage shifter that worked with 3V3 and 5 V, with some calculated diodes and resistors.

NAN: Tell us about your first project. Where were you at the time and what did you learn from the experience?


Eric’s Butler robot was his first electronics project. He started building it when he was still in high school.

ERIC: The Butler robot was my first real electronics project. I started building it in ninth grade, and for a really stupid reason. I just wanted to build a personal robot, like on TV. My first version of the Butler robot was cobbled together using an old laptop, a USB-to-I/O converter called Phidgets, and old wheelchair motors I bought on eBay.

I didn’t use anything fancy for this robot, all the software was written in Visual Basic and ran on Windows XP. For motor controllers, I used some old DPDT automotive relays I had lying around. They did the job but obviously I wasn’t able to PWM them for speed control.

My second version came about two years later, and was built with the intention of winning the Instructables Robot contest. I didn’t win first place, but my tutorial “How to Build a Butler Robot” placed in the top 10 and was mentioned in The Instructables Book in print. This version was a cleaner version of everything I had done before. I built a sleek black robot body (at least it was sleek back then!) and fabricated an upside-down bowl-shaped head that housed the webcam. The electronics were basically the same. The main new features were a basic robot arm that poured you a drink (two servos and a large DC motor) and a built-in mini fridge. I also got voice command to work really well by hooking up my Visual Basic software with Dragon’s speech-to-text converter.

The Butler robot was a great project and I learned a lot about electronics and software from doing it. If I were to build a Butler robot right now, I’d do it completely differently. But I think it was an important to my engineering career and it taught me that anything is possible with some hacking and hard work.

At the same time as I was doing my Butler robot (probably around 2008), I lucked out and was hired by an entertainer in Hong Kong. He saw my Butler robot online and hired me to build him a dancing robot that was synced to music. We solved the issue of syncing to music by putting dual-tone multi-frequency (DTMF) tones on the left channel audio and music on the right channel. The right channel went to speakers and the left channel went to a decoder that translated DTMF tone sequences to robot movement. This was good because all the data and dance moves were part of the same audio file. All we had to do was prepare special audio files and the robot would work with any music player (e.g., iPod, laptop, CD, etc.). The robot is used in shows to this day, and my performer client even hired a professional cartoon voice actor to give the robot a personality.

NAN: You were an adjunct professor at the Cooper Union for the Advancement of Science and Art in New York City. What types of courses did you teach and what did you enjoy most about teaching?

ERIC: I will be entering my senior year at Cooper Union in the Fall 2014. Two years ago, I took a year off from school to pursue my work. This past year I completed my junior year. I taught a semester of “Microcontroller Projects” at Cooper Union during my year off from being a student. We built a lot of really great projects using Arduino. One final project that really impressed me was a small robot car that parallel parked itself. Another project was a family of spider robots that were remotely controlled and could shrink up into a ball.

Cooper Union is filled with really bright students and teaching exposed me to the different thought processes people have when trying to build a solution. I think teaching helped me grow as a person and helped me understand that in engineering—and possibly in life—there is no one right answer. There are different paths to the same destination. I really enjoyed teaching because it made me evaluate my understanding about electronics, software, and robotics. It forced me to make sure I really understood what was going on in intricate detail.

NAN: You have competed in robotics competitions including RoboCup in Austria. Tell us about these experiences—what types of robots did you build for the competitions?


Eric worked with his high school’s robotics team to design this robot for a RoboCup competition.

ERIC: In high school I was the robotics team captain and we built a line-following robot and a soccer robot to compete in RoboCup Junior in the US. We won first place in the RoboCup Junior Northeast Regional and were invited to compete in Austria for the International RoboCup Junior games. So we traveled as a team to Austria to compete and we got to see a lot of interesting projects and many other soccer teams compete. I remember the Iranian RoboCup Junior team had a crazy robot that competed against us; it was built out of steel and looked like a miniature tank.

My best memory from Austria was when our robot broke and I had to fix it. Our robot was omnidirectional with four omni wheels in each corner that let it drive at any angle or orientation it wanted. It could zigzag across the field without a problem. At our first match, I put the robot down on the little soccer field to compete… and it wouldn’t move. During transportation, one of the motors broke. Disappointed, we had to forfeit that match. But I didn’t give up. I removed one of the wheels and rewrote the code to operate with only three motors functional. Again we tried to compete, and again another motor appeared to be broken. I removed yet another wheel and stuck a bottle cap as a caster wheel on the back. I rewrote the code, which was running on a little Microchip Technology PIC microcontroller, and programmed the robot to operate with only two wheels working. The crippled robot put up a good fight, but unfortunately it wasn’t enough. I think we scored one goal total, and that was when the robot had just two wheels working.

After the competition, during an interview with the judges, we had a laugh comparing our disabled robot to the videos we took back home with the robot scoring goal after goal. I learned from that incident to always be prepared for the worst, do your best, and sometimes stuff just happens. I’m happy I tried and did my best to fix it, I have no regrets. I have a some of the gears from that robot at home on display as a reminder to always prepare for emergencies and to always try my best.

NAN: What was the last electronics-design related product you purchased and what type of project did you use it with?

ERIC: The last product would be an op-amp I bought, probably the 411 chip. For a current project, I had to generate a –5-to-5-V analog signal from a microcontroller. My temporary solution was to RC filter the PWM output from the op-amp and then use an amplifier with a
gain of 2 and a 2.5-V “virtual ground.” The result is that 2.5 V is the new “zero” voltage. You can achieve –5 V by giving the op-amp 0 V, a –2.5-V difference that is amplified by 2 to yield 5 V. Similarly, 5 V is a 2.5-V difference from the virtual ground, amplified by 2 it provides a 5-V output.

NAN: What do you consider to be the “next big thing” in the industry?

ERIC: I think the next big thing will be personalized health care via smartphones. There are already some insulin pumps and heart monitors that communicate with special smartphone apps via Bluetooth. I think that’s excellent. We have all this computing power in our pockets, we should put it to good use. It would be nice to see these apps educating smartphone users—the patients themselves— about their current health condition. It might inspire patients/users to live healthier lifestyles and take care of themselves. I don’t think the FDA is completely there yet, but I’m excited to see what the future will bring. Remember, the future is what you build it to be.

HackRVA (Richmond, VA, USA)

HackRVA Sign4HackRVA is a Richmond-based makerspace. They like to take things apart, put them back together, figure out how they work, and create new things. Their mission? To learn and make stuff sharing tools and knowledge in technology; including Arduino, Makerbot, Linux, and the Open Source movement.

Aaron Nipper will tell us a little more.

Location 1600 Roseneath Road, Suite E, Richmond, VA 23230
Members 65

What’s your meeting space like? 

Our space is about 2,000 square feet. We have an AV and general meeting area, a tech lab, and a fab lab.

What’s in your “toolbox”?

  • Two 3D printers
  • Laser cutter
  • Lots of soldering stations
  • O-scopes
  • Hand and power tools
  • A computer lab

Are there any tools your group really wants or needs?

A CNC Router — like a shopbot. Can’t wait to build that first wiki-house!

Arduino, Raspberry Pi, embedded security… which embedded technologies does your group work with most frequently? 

We use all that stuff. Arduino, R-Pi, whatever we can get our hands on! We’ve designed, from scratch, PCB Badges for RichSec security conference the last three years. Click here to learn more about the PCB Badges project.

What have you been working on lately?

For the past three years, we’ve designed those PCB badges for the RichSec security conference. Here’s another recent build where a member took a Power Wheels and made it Xbox controller driven. Check out the video below or click here to read more about that project.

Do you have any events or initiatives you’d like to tell us about? Where can we learn more about them?

You can learn more about us at We host the Richmond Maker Guild, have regular Saturday Hackathons, as well as a Noise Night. Members are always coming up with creative events!

Any words of advice for fellow hackers?

My personal motto is fail often, teach others, and post to the web. All those things help me learn and think about projects better.

Want to know more about what HackRVA does? Check out their Facebook page and website.

Show us your hackerspace! Tell us about your group! Where does your group design, hack, create, program, debug, and innovate? Do you work in a 20′ × 20′ space in an old warehouse? Do you share a small space in a university lab? Do you meet a local coffee shop or bar? What sort of electronics projects do you work on? Submit your hackerspace and we might feature you on our website!

Q&A: Raspberry Pi Innovation

Orlando, FL-based web app developer and blogger Shea Silverman recently received Kickstarter funding for the latest version of PiPlay, his Raspberry Pi-based OS. Shea and I discussed his ongoing projects, his Raspberry Pi book, and what’s next for PiPlay.—Nan Price, Associate Editor



Shea Silverman

NAN: What is your current occupation?

SHEA: Web applications developer with the Center for Distributed Learning at the University of Central Florida (UCF).

NAN: Why and when did you decide to start your blog?

SHEA: I’ve been blogging on and off for years, but I could never keep to a schedule or really commit myself to writing. After I started working on side projects, I realized I needed a place to store tips and tricks I had figured out. I installed WordPress, posted some PhoneGap tips, and within a day got a comment from someone who had the same issue, and my tips helped them out. I have been blogging ever since. I make sure to post every Friday night.

NAN: Tell us about PiPlay, the Raspberry Pi OS. Why did you start the OS? What new developments, if any, are you working on?


Shea’s PiPlay Raspberry Pi OS recently reached 400% funding on Kickstarter.

SHEA: PiPlay is a gaming and emulation distribution for the Raspberry Pi single-board computer. It is built on top of the Raspbian OS, and tries to make it as easy as possible to play games on your Raspberry Pi. My blog got really popular after I started posting binaries and tutorials on how to compile different emulators to the Raspberry Pi, but I kept getting asked the same questions and saw users struggling with the same consistent issues.

I decided I would release a disk image with everything preconfigured and ready to be loaded onto an SD card. I’ve been adding new emulators, games, and tools to it ever since.

I just recently completed a Kickstarter that is funding the next release, which includes a much nicer front end, a web GUI, and a better controller configuration system.

NAN: You wrote Instant Raspberry Pi Gaming. Do you consider this book introductory or is it written for the more experienced engineer?

SHEA: Instant Raspberry Pi Gaming is written like a cookbook with recipes for doing various tasks. Some of them are very simple, and they build up to some more advanced recipes. One of the easier tasks is creating your user account on the Pi Store, while the more advanced recipes have you working with Python and using an API to interact with Minecraft.

Readers will learn how to setup a Raspberry Pi, install and use various emulators and games, a bit about the Minecraft API, and common troubleshooting tips.


The Pitroller is a joystick and buttons hooked up to the GPIO pins of a Raspberry Pi, which can act as a controller or keyboard for various emulators.

NAN: You are a member of FamiLAB, an Orlando, FL-based community lab/hackerspace. What types of projects have you worked on at the lab?


Disney director Rich Moore poses with Shea’s miniature arcade machine. The machine was based on Fix It Felix Jr. from Disney’s Wreck It Ralph.

SHEA: I spend a lot of time at the lab using the laser cutter. Creating a 2-D vector in Inkscape, and then watching it be cut out on a piece of wood or acrylic is really inspiring. My favorite project was making a little arcade machine featuring Fix It Felix Jr. from Wreck It Ralph. A marketing person from Disney was able to get it into the hands of the director Rich Moore. He sent me a bunch of pictures of himself holding my little arcade machine next to the full size version.

NAN: Give us a little background information. How did you become interested in technology?

SHEA: My mom always likes to remind me that I’ve been using computers since I was 2. My parents were very interested in technology and encouraged my curiosity when it came to computers. I always liked to take something apart and see how it worked, and then try to put it back together. As the years went on, I’ve devoted more and more time to making technology a major part of my life.

NAN: Tell us about the first embedded system you designed.

SHEA: I have a lot of designs, but I don’t think I’ve ever finished one. I’ll be halfway into a project, learn about something new, then cannibalize what I was working on and repurpose it for my new idea. One of the first embedded projects I worked on was a paintball board made out of a PICAXE microcontroller. I never got it small enough to fit inside the paintball marker, but it was really cool to see everything in action. The best part was when I finally had that “ah-ha!” moment, and everything I was learning finally clicked.

NAN: What was the last electronics-design related product you purchased and what type of project did you use it with?

SHEA: At UCF, one of our teams utilizes a ticket system for dealing with requests. Our department does a hack day each semester, so my coworker and I decided to rig up a system that changes the color of the lights in the office depending on the urgency of requests in the box. We coded up an API and had a Raspberry Pi ping the API every few minutes for updates. We then hooked up two Arduinos to the Raspberry Pi and color-changing LED strips to the Arduinos. We set it up and it’s been working for the past year and a half, alerting the team with different colors when there is work to do.

NAN: Are you currently working on or planning any projects?

SHEA: My Kickstarter for PiPlay just finished at 400% funding. So right now I’m busy working on fulfilling the rewards, and writing the latest version of PiPlay.

NAN: What do you consider to be the “next big thing” in the industry?

SHEA: Wearable computing. Google Glass, the Pebble smart watch, Galaxy Gear—I think these are all great indicators of where our technology is heading. We currently have very powerful computers in our pockets with all kinds of sensors and gadgets built in, but very limited ways to physically interact with them (via the screen, or a keypad). If we can make the input devices modular, be it your watch, a heads-up display, or something else, I think that is going to spark a new revolution in user experiences.

Execute Open-Source Arduino Code in a PIC Microcontroller Using the MPLAB IDE

The Arduino single-board computer is a de facto standard tool for developing microcomputer applications within the hobbyist and educational communities. It provides an open-source hardware (OSH) environment based on a simple microcontroller board, as well as an open-source (OS) development environment for writing software for the board.

Here’s an approach that enables Arduino code to be configured for execution with the Microchip Technology PIC32MX250F128B small-outline 32-bit microcontroller. It uses the Microchip Technology MPLAB X IDE and MPLAB XC32 C Compiler and the Microchip Technology Microstick II programmer/debugger.

Your own reasons for using this approach will depend on your personal needs and background. Perhaps as a long-term Arduino user, you want to explore a new processor performance option with your existing Arduino code base. Or, you want to take advantage of or gain experience with the Microchip advanced IDE development tools and debug with your existing Arduino code. All of these goals are easily achieved using the approach and the beta library covered in this article.

Several fundamental open-source Arduino code examples are described using the beta core library of Arduino functions I developed. The beta version is available, for evaluation purposes only, as a free download from the “Arduino Library Code for PIC32” link on my KibaCorp company website, From there, you can also download a short description of the Microstick II hardware configuration used for the library.

To illustrate the capabilities in their simplest form, here is a simple Blink LED example from my book Beginner’s Guide to Programming the PIC32. The example shows how this custom library makes it easy to convert Arduino code to a PIC32 binary file.

The Arduino code example is as follows: Wire an LED through a 1-K resistor to pin 13 (D7) of the Arduino. An output pin is configured to drive an LED using pinMode () function under setup (). Then under loop () this output is set high and then low using digitalWrite () and delay () functions to blink the LED. The community open-source Arduino code is:

The open-source example uses D13 or physical pin 13 on the Arduino. In relation to the PIC32MX, the D13 is physical pin 25. Pin 25 will be used in prototyping wiring.

Now, let’s review and understand the PIC32 project template and its associated “wrapping functions.”  The Arduino uses two principal functions: setup () to initialize the system and loop () to run a continuous execution loop. There is no Main function. Using the Microchip Technololgy XC32 C compiler, we are constrained to having a Main function. The Arduino setup () and loop () functions can be accommodated, but only as part of an overall template Main “wrapping” function. So within our PIC32 template, we accommodate this as follows:

Listing 2

This piece of code is a small but essential part of the template. Note that in this critical wrapping function, setup () is called once as in Arduino and loop () is configured to be called continuously (simulating the loop () function in Arduino) through the use of a while loop in Main.

The second critical wrapping function for our template is the use of C header files at the beginning of the code. The XC32 C compiler uses the C compiler directive #include reference files within the Main code. Arduino uses import, which is a similar construct that is used in higher-level languages such as Java and Python, which cannot be used by the MPLAB XC32 C.

The two include files necessary for our first example are as follows:

Listing 3

System.h references all the critical Microchip library functions supporting the PIC32MX250F128B. The Ardunio.h provides the Arduino specific library function set. Given these two key “wrapper” aspects, where does the Arduino code go? This is best illustrated with a side-by-side comparison between Arduino code and its Microchip equivalent. The Arduino code is essentially positioned between the wrapper codes as part of the Main function.

Blink side-by-side comparison

Blink side-by-side comparison

This approach enables Arduino code to execute on a Microchip PIC32 within an MPLAB X environment. Note that the Arduino code void setup () now appears as void setup (void), and void loop () appears as void loop (void). This is a minor inconvenience but again necessary for our C environment syntax for C prototype function definitions. Once the code is successfully compiled, the environment enables you to have access to the entire built-in tool suite of the MPLAB X and its debugger tool suite.

Configure the Microstick II prototype as in the following schematic. Both the schematic and prototype are shown below:

Exercise 1 schematic

Exercise 1 schematic

Exercise 1 prototype

Exercise 1 prototype

Table 1 compares Arduino core functionality to what is contained in the Microchip PIC32 expanded beta library. In the beta version, I added additional C header files to accomplish the necessary library functionality. Table 2 compares variable types between Arduino and PIC32 variable types. Both Table 1 and Table 2 show the current beta version has a high degree of Arduino core library functionality. Current limitations are the use of only one serial port, interrupt with INT0 only, and no stream capability. In addition, with C the “!” operator is used for conditional test only and not as a complement function, as in Arduino. To use the complement function in C, the “~” operator is used. The library is easily adapted to other PIC32 devices or board types.

Table 1

Table 1: Arduino vs Microchip Technology PIC32 core library function comparison

Talble 2

Table 2: Arduino vs Microchip Technology PIC32 core library variable types

If you use interrupts, you must identify to C the name of your interrupt service routine as used in your Arduino script. See below:

Interrupt support

Interrupt support

For more information on the beta release or to send comments and constructive criticism, or to report any detected problems, please contact me here.

Four test case examples demonstrating additional core library functions are shown below as illustrations.

Serial communications

Serial communications

Serial find string test case

Serial find string test case

Serial parse INT

Serial parse INT



Editor’s Note: Portions of this post first appeared in Tom Kibalo’s book Beginner’s Guide to Programming the PIC32 (Electronics Products, 2013). They are reprinted with permission from Chuck Hellebuyck, Electronic Products. If you are interested in reading more articles by Kibalo, check out his two-part Circuit Cellar “robot boot camp” series posted in 2012 : “Autonomous Mobile Robot (Part 1): Overview & Hardware” and “Autonomous Mobile Robot (Part 2): Software & Operation.”


Tom Kibalo

Tom Kibalo

Tom Kibalo is principal engineer at a large defense firm and president of KibaCorp, a company dedicated to DIY hobbyist, student, and engineering education. Tom, who is also an Engineering Department adjunct faculty member at Anne Arundel Community College in Arnold, MD, is keenly interested in microcontroller applications and embedded designs. To find out more about Tom, read his 2013 Circuit Cellar member profile.

DIY IoT: Build a ‘Net-Connected System Today

It’s time to join the Internet of Things (IoT) revolution. Try building a ‘Net-enabled design with WIZnet’s W5500 “smart” Ethernet chip. It’s easier than you think.

In a thorough introduction to the technology, Tom Cantrell presented a garage door monitoring design. He explained:

The W5500 (see Figure 1) starts with a standard 10/100 Ethernet interface (i.e., MAC and PHY) but then goes further with large RAM buffers (16-KB transmit and 16-KB receive) and hardware TCP/IP protocol processing. I discovered WIZnet’s first chip, the  W3100, way back in 2001. Of course by now, as with all things  silicon, the new W5500 is better, faster, and  lower cost. But the concept is still exactly  the same: “Internet enable” applications by  handling the network chores in hardware so  the application microcontroller doesn’t have to do it in software.

Cantrell - WIZ550io

Figure 1: The WIZnet W5500 is an Ethernet chip with a difference—large RAM buffers and hardware TCP/IP processing that make it easy for any microcontroller to go online.

The large RAM buffers help decouple the  microcontroller from network activity. In a  recent project (see my article, “Weatherize  Your Embedded App,” Circuit Cellar 273,  2013), I used the RAM to receive an entire  10-KB+ webpage, completely eliminating the  need for the microcontroller to juggle data at  network speed. And any of the 32-KB on-chip  RAM that isn’t needed for network buffering  is free for general-purpose use, a big plus for  typically RAM-constrained microcontrollers. The other major WIZnet hardware assist  is TCP/IP processing using IP addresses, sockets, and familiar commands including OPEN, CONNECT, SEND, RECEIVE, DISCONNECT.  The high-level interface to the network frees  up microcontroller cycles and code space that  would otherwise be needed for a software TCP/IP stack.

Cantrell goes on to present his design for a ‘Net-connected garage door monitoring system.

For prototyping, check out the WIZnet  ioShield (see Photo 1), which is a baseboard  for the WIZ550io that includes an SD card  socket. There are ioShields for different  platforms (e.g., Arduino, LaunchPad,  mbed, etc.), and with 0.1” headers they are  breadboard friendly.

Photo 1: If you want a fancy server with lots of eye candy, a microSD card is the way to go. The WIZnet ioShields include the card socket and are available for various platforms. The Arduino version is shown here.

Photo 1: If you want a fancy server with lots of eye candy, a microSD card is the way to go. The WIZnet ioShields include the card socket and are available for various platforms. The Arduino version is shown here.

Cantrell prototyped a client version of what he calls his “garage  door ‘Thing’ using an Arduino  and a WIZ550io connected to Exosite (see Photo 2).

A prototype of the client version of my garage “Thing” is shown.

Photo 2: A prototype of the client version of my garage “Thing”

Wondering how to get two clients (e.g., ) to interact with each other? Cantrell used Exosite.

Over on the Exosite website, after signing up for a  free “Developer” account, it was a quick and easy mainly point-and-click exercise to configure my “Device,” “Data,”  “Events,” and “Alerts” (see Photo 3).  As a client, there’s no need to keep the “Thing’s”  Ethernet link powered all the time. Data only needs to  be sent when the garage door opens or closes, but I also  recommend sending a periodic heartbeat just in case. My  garage door monitor will only generate a minute or two  of network activity (i.e., door state changes and hourly  heartbeats) per day, so there’s opportunity for significant  energy savings compared to a 24/7 server.

It only takes a few minutes to set up a simple Exosite dashboard including an e-mail alert. I can “see“ my  garage door without getting off the couch and now, via Exosite, from the farthest reaches of the web.

It only takes a few minutes to set up a simple Exosite dashboard including an e-mail alert. I can “see“ my garage door without getting off the couch and now, via Exosite, from the farthest reaches of the web.

You can download the entire article,  “Connect the Magic: An Introduction to the WIZnet W550,” for free to learn about Cantrell’s garage door control system built with a WIZnet and an Arduino Uno.

Editor’s note: If you have an idea for an innovative, ’Net-enabled electronics system, this is your opportunity to share your original design with the world. Enter the WIZnet Connect the Magic 2014 Design Challenge for a chance to win a share of $15,000 in prizes and gain recognition by Elektor International Media and Circuit Cellar. WIZnet is the sponsor. Eligible entries will be judged on their technical merit, originality, usefulness, cost-effectiveness, and design optimization. The Entry submission deadline is 12:00 PM EST August 3, 2014. How to enter: Implement WIZnet’s WIZ550io Ethernet module, or W5500 chip, in an innovative design; document your project; and then submit your entry. The complete rules and regulations are available on the Challenge webpage.


Q&A: Embedded Systems Consultant

Elecia White is an embedded systems engineer, consultant, author, and innovator. She has worked on a variety of projects: DNA scanners, health-care monitors, learning toys, and fingerprint recognition.—Nan Price, Associate Editor


NAN: Tell us about your company Logical Elegance. When and why did you start the company? What types of services do you provide?

ELECIA: Logical Elegance is a small San Jose, CA-based consulting firm specializing in embedded systems. We do system analysis, architecture, and software implementation for a variety of devices.

Elecia White

Elecia White

I started the company in 2004, after leaving a job I liked for a job that turned out to be horrible. Afterward, I wasn’t ready to commit to another full-time job; I wanted to dip my toe in before becoming permanent again.

I did eventually take another full-time job at ShotSpotter, where I made a gunshot location system. Logical Elegance continued when my husband, Chris, took it over. After ShotSpotter, I returned to join him. While we have incorporated and may take on a summer intern, for the most part Logical Elegance is only my husband and me.

I like consulting, it lets me balance my life better with my career. It also gives me time to work on my own projects: writing a book and articles, playing with new devices, learning new technologies. On the other hand, I could not have started consulting without spending some time at traditional companies. Almost all of our work comes from people we’ve worked with in the past, either people we met at companies where we worked full time or people who worked for past clients.

Here is Elecia’s home lab bench. She conveniently provided notes.

Here is Elecia’s home lab bench. She conveniently provided notes.

NAN: Logical Elegance has a diverse portfolio. Your clients have ranged from Cisco Systems to LeapFrog Enterprises. Tell us about some of your more interesting projects.

ELECIA: We are incredibly fortunate that embedded systems are diverse, yet based on similar bedrock. Once you can work with control loops and signal processing, the applications are endless. Understanding methodologies for concepts such as state machines, interrupts, circular buffers, and working with peripherals allows us to put the building blocks together a different way to suit a particular product’s need.

For example, for a while there, it seemed like some of my early work learning how to optimize systems to make big algorithms work on little processors would fall to the depths of unnecessary knowledge. Processors kept getting more and more powerful. However, as I work on wearables, with their need to optimize cycles to extend their battery life, it all is relevant again.

We’ve had many interesting projects. Chris is an expert in optical coherence tomography (OCT). Imagine a camera that can go on the end of a catheter to help a doctor remove plaque from a clogged artery or to aid in eye surgery. Chris is also the networking expert. He works on networking protocols such as Locator/ID Separation Protocol (LISP) and multicast.

I’m currently working for a tiny company that hopes to build an exoskeleton to help stroke patients relearn how to walk. I am incredibly enthusiastic about both the application and the technology.

That has been a theme in my career, which is how I’ve got this list of awesome things I’ve worked on: DNA scanners, race cars and airplanes, children’s toys, and a gunshot location system. The things I leave off the list are more difficult to describe but no less interesting to have worked on: a chemical database that used hydrophobicity to model uptake rates, a medical device for the operating room and ICU, and methods for deterring fraud using fingerprint recognition on a credit card.

Elecia says one of the great things about the explosion of boards and kits available is being able to quickly build a system. However, she explains, once the components work together, it is time to spin a board. (This system may be past that point.)

Elecia says one of the great things about the explosion of boards and kits available is being able to quickly build a system. However, she explains, once the components work together, it is time to spin a board. (This system may be past that point.)

In the last few years, Chris and I have both worked for Fitbit on different projects. If you have a One pedometer, you have some of my bits in your pocket.

The feeling of people using my code is wonderful. I get a big kick seeing my products on store shelves. I enjoyed working with Fitbit. When I started, it was a small company expanding its market; definitely the underdog. Now it is a success story for the entire microelectromechanical systems (MEMS) industry.

Not everything is rosy all the time though. For one start-up, the algorithms were neat, the people were great, and the technology was a little clunky but still interesting. However, the client failed and didn’t pay me (and a bunch of other people).

When I started consulting, I asked a more experienced friend about the most important part. I expected to hear that I’d have to make myself more extroverted, that I’d have to be able to find more contracts and do marketing, and that I’d be involved in the drudgery of accounting. The answer I got was the truth: the most important part of consulting is accounts receivable. Working for myself—especially with small companies—is great fun, but there is a risk.

NAN: How did you get from “Point A” to Logical Elegance?

ELECIA: ”Point A” was Harvey Mudd College in Claremont, CA. While there, I worked as a UNIX system administrator, then later worked with a chemistry professor on his computational software. After graduation, I went to Hewlett Packard (HP), doing standard software, then a little management. I was lured to another division to do embedded software (though we called it firmware).

Next, a start-up let me learn how to be a tech lead and architect in the standard start-up sink-or-swim methodology. A mid-size company gave me exposure to consumer products and a taste for seeing my devices on retailer’s shelves.

From there, I tried out consulting, learned to run a small business, and wrote a Circuit Cellar Ink article “Open Source Code Guide” (Issue 175, 2005). I joined another tiny start-up where I did embedded software, architecture, management, and even directorship before burning out. Now, I’m happy to be an embedded software consultant, author, and podcast host.

NAN: You wrote Making Embedded Systems: Design Patterns for Great Software (O’Reilly Media, 2011). What can readers expect to learn from the book?

ELECIA: While having some industry experience in hardware or software will make my book easier to understand, it is also suitable for a computer science or electrical engineering college student.

It is a technical book for software engineers who want to get closer to the hardware or electrical engineers who want to write good software. It covers many types of embedded information: hardware, software design patterns, interview questions, and a lot of real-world wisdom about shipping products.

Elecia White's BookMaking Embedded Systems is intended for engineers who are in transition: the hardware engineer who ends up writing software or the software engineer who suddenly needs to understand how the embedded world is different from pure software.

Unfortunately, most college degrees are either computer science or electrical engineering. Neither truly prepares for the half-and-half world of an embedded software engineer. Computer science teaches algorithms and software design methodology. Electrical engineering misses both of those topics but provides a practical tool kit for doing low-level development on small processors. Whichever collegiate (or early career) path, an embedded software engineer needs to have familiarity with both.

I did a non-traditional major that was a combination of computer science and engineering systems. I was prepared for all sorts of math (e.g., control systems and signal processing) and plenty of programming. All in all, I learned about half of the skills I needed to do firmware. I was never quite sure what was correct and what I was making up as I went along.

As a manager, I found most everyone was in the same boat: solid foundations on one side and shaky stilts on the other. The goal of the book is to take whichever foundation you have and cantilever a good groundwork to the other half. It shouldn’t be 100% new information. In addition to the information presented, I’m hoping most people walk away with more confidence about what they know (and what they don’t know).

Elecia was a judge at the MEMS Elevator Pitch Session at the 2013 MEMS Executive Congress in Napa, CA.

Elecia was a judge at the MEMS Elevator Pitch Session at the 2013 MEMS Executive Congress in Napa, CA.

NAN: How long have you been designing embedded systems? When did you become interested?

ELECIA: I was a software engineer at the NetServer division at HP. I kept doing lower-level software, drivers mostly, but for big OSes: WinNT, OS/2, Novell NetWare, and SCO UNIX (a list that dates my time there).

HP kept trying to put me in management but I wasn’t ready for that path, so I went to HP Labs’s newly spun-out HP BioScience to make DNA scanners, figuring the application would be more interesting. I had no idea.

I lit a board on fire on my very first day as an embedded software engineer. Soon after, a motor moved because my code told it to. I was hooked. That edge of software, where the software touches the physical, captured my imagination and I’ve never looked back.

NAN: Tell us about the first embedded system you designed. Where were you at the time? What did you learn from the project?

ELECIA: Wow, this one is hard. The first embedded system I designed depends on your definition of “designed.” Going from designing subsystems to the whole system to the whole product was a very gradual shift, coinciding with going to smaller and smaller companies until suddenly I was part of the team not only choosing processors but choosing users as well.

After I left the cushy world of HP Labs with a team of firmware engineers, several electrical engineers, and a large team of software engineers who were willing to help design and debug, I went to a start-up with fewer than 50 people. There was no electrical engineer (except for the EE who followed from HP). There was a brilliant algorithms guy but his software skills were more MATLAB-based than embedded C. I was the only software/firmware engineer. This was the sort of company that didn’t have source version control (until after my first day). It was terrifying being on my own and working without a net.

I recently did a podcast about how to deal with code problems that feel insurmountable. While the examples were all from recent work, the memories of how to push through when there is no one else who can help came from this job.

Elecia is shown recording a Making Embedded Systems episode with the founders of electronics educational start-up Light Up. From left to right: Elecia’s husband and producer Christopher White, host Elecia White, and guests Josh Chan and Tarun Pondicherry.

Elecia is shown recording a Making Embedded Systems episode with the founders of electronics educational start-up Light Up. From left to right: Elecia’s husband and producer Christopher White, host Elecia White, and guests Josh Chan and Tarun Pondicherry.

NAN: Are you currently working on or planning any projects?

ELECIA: I have a few personal projects I’m working on: a T-shirt that monitors my posture and a stuffed animal that sends me a “check on Lois” text if an elderly neighbor doesn’t pat it every day. These don’t get nearly enough of my attention these days as I’ve been very focused on my podcast: Making Embedded Systems on iTunes, Instacast, Stitcher, or direct from

The podcast started as a way to learn something new. I was going to do a half-dozen shows so I could understand how recording worked. It was a replacement for my normal community center classes on stained glass, soldering, clay, hula hooping, laser cutting, woodshop, bookbinding, and so forth.

However, we’re way beyond six shows and I find I quite enjoy it. I like engineering and building things. I want other people to come and play in this lovely sandbox. I do the show because people continue to share their passion, enthusiasm, amusement, happiness, spark of ingenuity, whatever it is, with me.

To sum up why I do a podcast, in order of importance: to talk to people who love their jobs, to share my passion for engineering, to promote the visibility of women in engineering, and to advertise for Logical Elegance (this reason is just in case our accountant reads this since we keep writing off expenses).

NAN: What are your go-to embedded platforms? Do you have favorites, or do you use a variety of different products?

ELECIA: I suppose I do have favorites but I have a lot of favorites. At any given time, my current favorite is the one that is sitting on my desk. (Hint!)

I love Arduino although I don’t use it much except to get other people excited. I appreciate that at the heart of this beginner’s board (and development system) is a wonderful, useful processor that I’m happy to work on.

I like having a few Arduino boards around, figuring that I can always get rid of the bootloader and use the Atmel ATmega328 on its own. In the meantime, I can give them to people who have an idea they want to try out.

For beginners, I think mbed’s boards are the next step after Arduino. I like them but they still have training wheels: nice, whizzy training wheels but still training wheels. I have a few of those around for when friends’ projects grow out of Arduinos. While I’ve used them for my own projects, their price precludes the small-scale production I usually want to do.

Professionally, I spend a lot of time with Cortex-M3s, especially those from STMicroelectronics and NXP Semiconductors. They seem ubiquitous right now. These are processors that are definitely big enough to run an RTOS but small enough that you don’t have to. I keep hearing that Cortex-M0s are coming but the price-to-performance-to-power ratio means my clients keep going to the M3s.

Finally, I suppose I’ll always have a soft spot for Texas Instruments’s C2000 line, which is currently in the Piccolo and Delfino incarnations. The 16-bit byte is horrible (especially if you need to port code to another processor), but somehow everything else about the DSP does just what I want. Although, it may not be about the processor itself: if I’m using a DSP, I must be doing something mathy and I like math.

NAN: Do you have any predictions for upcoming “hot topics?”

ELECIA: I’m most excited about health monitoring. I’m surprised that Star Trek and other science fiction sources got tricorders right but missed the constant health monitoring we are heading toward with the rise of wearables and the interest in quantified self.
I’m most concerned about connectivity. The Internet of Things (IoT) is definitely coming, but many of these devices seem to be more about applying technology to any device that can stand the price hit, whether it makes sense or not.

Worse, the methods for getting devices connected keeps fracturing as the drive toward low-cost and high functionality leads the industry in different directions. And even worse, the ongoing battle between security and ease of use manages to give us things that are neither usable nor secure. There isn’t a good solution (yet). To make progress we need to consider the application, the user, and what they need instead of applying what we have and hoping for the best.

A Workspace for “Engineering Magic”


Photo 1—Brandsma describes his workspace as his “little corner where the engineering magic happens.”

Sjoerd Brandsma, an R&D manager at CycloMedia, enjoys designing with cameras, GPS receivers, and transceivers. His creates his projects in a small workspace in Kerkwijk, The Netherlands (see Photo 1). He also designs in his garage, where he uses a mill and a lathe for some small and medium metal work (see Photo 2).


Photo 2—Brandsma uses this Weiler lathe for metal work.

The Weiler lathe has served me and the previous owners for many years, but is still healthy and precise. The black and red mill does an acceptable job and is still on my list to be converted to a computer numerical control (CNC) machine.

Brandsma described some of his projects.


Photo 3—Some of Brandsma’s projects include an mbed-based camera project (left), a camera with an 8-bit parallel databus interface (center), and an MP3 player that uses a decoder chip that is connected to an mbed module (right).

I built a COMedia C328 UART camera with a 100° lens placed on a 360° servomotor (see Photo 3, left).  Both are connected to an mbed module. When the system starts, the camera takes a full-circle picture every 90°. The four images are stored on an SD card and can be stitched into a panoramic image. I built this project for the NXP mbed design challenge 2010 but never finished the project because the initial idea involved doing some stitching on the mbed module itself. This seemed to be a bit too complicated due to memory limitations.

I built this project built around a 16-MB framebuffer for the Aptina MT9D131 camera (see Photo 3, center). This camera has an 8-bit parallel databus interface that operates on 6 to 80 MHz. This is way too fast for most microcontrollers (e.g., Arduino, Atmel AVR, Microchip Technology PIC, etc.). With this framebuffer, it’s possible to capture still images and store/process the image data at a later point.

This project involves an MP3 player that uses a VLSI VS1053 decoder chip that is connected to an mbed module (see Photo 3, right). The great thing about the mbed platform is that there’s plenty of library code available. This is also the case for the VS1053. With that, it’s a piece of cake to build your own MP3 player. The green button is a Skip button. But beware! If you press that button it will play a song you don’t like and you cannot skip that song.

He continued by describing his test equipment.


Photo 4—Brandsma’s test equipment collection includes a Tektronix TDS220 oscilloscope (top), a Total Phase Beagle protocol analyzer (second from top), a Seeed Technology Open Workbench Logic Sniffer (second from bottom), and a Cypress Semiconductor CY7C68013A USB microcontroller (bottom).

Most of the time, I’ll use my good old Tektronix TDS220 oscilloscope. It still works fine for the basic stuff I’m doing (see Photo 4, top). The Total Phase Beagle I2C/SPI protocol analyzer Beagle/SPI is a great tool to monitor and analyze I2C/SPI traffic (see Photo 4, second from top).

The red PCB is a Seeed Technology 16-channel Open Workbench Logic Sniffer (see Photo 4, second from bottom). This is actually a really cool low-budget open-source USB logic analyzer that’s quite handy once in a while when I need to analyze some data bus issues.

The board on the bottom is a Cypress CY7C68013A USB microcontroller high-speed USB peripheral controller that can be used as an eight-channel logic analyzer or as any other high-speed data-capture device (see Photo 4, bottom). It’s still on my “to-do” list to connect it to the Aptina MT9D131 camera and do some video streaming.

Brandsma believes that “books tell a lot about a person.” Photo 5 shows some books he uses when designing and or programming his projects.


Photo 5—A few of Brandsma’s “go-to” books are shown.

The technical difficulty of the books differs a lot. Electronica echt niet moeilijk (Electronics Made Easy) is an entry-level book that helped me understand the basics of electronics. On the other hand, the books about operating systems and the C++ programming language are certainly of a different level.

An article about Brandsma’s Sun Chaser GPS Reference Station is scheduled to appear in Circuit Cellar’s June issue.

HMI Development on Intelligent Displays

4dsystems_HRES4D Systems and Future Technology Devices International Limited (FTDI) (aka, FTDI Chip) recently introduced the 4DLCD-FT843. The intelligent display solution incorporates FTDI Chip’s FT800 Embedded Video Engine (EVE) with the subsequent introduction of two additional products. This combined product gives design engineers a foundation on which to quickly and easily construct human-machine interfaces (HMIs).

The first of these products is the ADAM (Arduino Display Adaptor Module). This 47.5-mm × 53.4-mm Arduino-compatible shield permits communication between the Arduino via the SPI. The shield is suitable for use with Arduino Uno, Due, Duemilanove, Leonardo, Mega 1280/2560, and Pro 5V. The shield’s micro-SD card provides the Arduino-based display system with ample data storage. The 4DLCD-FT843 can use the micro-SD card to retrieve objects (e.g., images, sounds, fonts, etc.). Drawing power from the Arduino’s 5-V bus, the ADAM regulates the 4DLCD-FT843’s supply to 3.3 V. The FT800 EVE controller can handle many of the graphics functions that would otherwise need to be managed by the Arduino.

The ADAM is complemented by the 4DLCD-FT843-Breakout. With a 26.5-mm × 12-mm footprint, this simple breakout module enables the 4DLCD-FT843 to be attached to a general host or breadboard for prototyping purposes. It features a 10-way FPC connection for attachment with the 4DLCD-FT843 along with a 10-way, 2.54-mm pitch male pin header that enables it to directly connect to the host board. Both products support a –10°C-to-70°C operational temperature range.

The EVE-driven 4DLCD-FT843 has a 4.3” TFT QWVGA display with a four-wire resistive touchscreen. It features a 64-voice polyphonic sound synthesizer, a mono PWM audio output, a programmable interrupt controller, a PWM dimming controller for the display’s backlight, and a flexible ribbon connector.

Contact 4D Systems or FTDI Chip for pricing.

4D Systems

Future Technology Devices International Limited (FTDI) (aka, FTDI Chip)