Etherkit, Microcontrollers

Market Research

It has been awfully quiet on the public front here for sure, but I have been working on quite a bit of things behind the scenes here at Etherkit Galactic HQ. It’s been a challenging year since I last wrote about the personal things going on here, but things have been going reasonable well after a rough half-year immediately following that post. I’m just about ready to attempt to revamp Etherkit, however there are still a few challenging roadblocks to overcome, and I could use a bit of guidance.

The most difficult issue is trying to re-bootstrap the business financially. I’m currently only selling the Si5351A Breakout Board, which obviously isn’t enough to expand a business upon. The possibility of a capital infusion unfortunately broke down, and so the only practical way forward at this point is most likely another crowdfunding campaign.

As mentioned in the opening paragraph, I have been working on various projects, and so I do have some candidates. Many of the projects that are in the works or only even in the planning stages require the use of a microcontroller, and so last year I decided to make my own Arduino-compatible microcontroller board family which I can then use as the heart of many of these products. I’ve taken a real liking to the Arduino Zero because of its speed and features, but the cost is fairly high and the standard Arduino form factor isn’t great for many purposes. Therefore, I have decided to make a new standalone board derived from the Zero which I call Empyrean, and you can see in the photo at the top of the post. It comes in two flavors: Alpha and Beta. The Alpha is based on the Atmel ATSAMD21G18A microcontroller, same as the Arduino Zero. The Beta uses a controller (ATSAMD21G16B) with a bit less flash and RAM than the Zero (but still more than an Arduino Uno), but is also priced similarly to the ATmega328 line of microcontrollers. Both come on a small board similar in size to the Nano and has nearly all of the same circuitry of the Arduino Zero except for the EDBG support.

It is true that there are a flood of Arduino clones out there and this makes entering the market with another one somewhat crazy. My value proposition for Empyrean is based on the confluence of breadboard-friendly form factor along with a wallet-friendly price. My target price point is around $15 for Alpha and $10 for Beta. While that is a fair bit more than your typical eBay Nano clone, Empyrean would also be quite a bit more powerful than a Nano, in both clock speed and available memory. So my question to you, dear reader, is whether you would be interested enough in this product to back a crowdfunding campaign in order to have it made? I do plan to make a serious push on a radio soon, but it would be nice to ramp up the business before that, while also solidifying the microcontroller platform that will be used in future products. Let me know what you think in the comments, or send me an email.

In the mean time, I thought I’d let you know that I’m working on a Rev D board spin of the Si5351A Breakout Board. You can see a prototype in beautiful OSHPark purple above. The most significant changes in this revision will be to change the coupling of the reference oscillator to the Si5351 XA input pin to meet datasheet specs and to panelize the board in preparation for future pick-and-place operations (they are currently hand-assembled!).

Perhaps even more interesting is that I also hope to be able to soon offer a frequency calibration report with every board sold. Thanks to LA3PNA, I am now in possession of a decent 10 MHz GPSDO to use as a lab reference, which will allow me to measure the frequency correction value accurately enough for hobbyist usage. I now have a small printer on hand, and so now what I need to do is add new code to my board test script to measure the correction value and print it for inclusion with each board sold. Stay tuned for notification when I’m ready to go live with this; hopefully soon.

Let me reiterate: I’d love to hear your thoughts about the above proposals. I’m interested in serving the needs of my customers. Thank you!

Coding, Cool Stuff, Etherkit, Wideband Transmission

Wideband Transmission #8

Another 10 mW WSPR Beacon

I enjoy writing up my projects, but it’s much better to get feedback to see that someone was actually able to take my writing and successfully duplicate my project. Via the Etherkit Twitter account, I received this from Tom Hall, AK2B regarding my last posted project:

Awesome work! Tom has been a great supporter of Etherkit from the beginning and I’d like to thank him for sharing his neat creations with the rest of us. It’s wonderful to see such a minimalist design perform so well!

More Coding Resources for Fun

I haven’t had a ton of free time here, but I do get snippets of time occasionally where I can sit with my notebook PC for a bit and mess around. As mentioned in some recent posts, I’ve been revisiting coding for fun, and I’ve stumbled upon quite a bit of new resources that are new to me and that I thought would be good to share.

The first one I’d like to mention is called Scratchapixel. I was curious about the mathematical methods behind 3D rendering, and some searching brought me to this exhaustive tutorial site. It’s not 100% complete yet, but most of the fundamentals of 3D graphics are already well-explained there. A fantastic resource if you are curious about the first principles of 3D rendering like me.

A related site is called Shadertoy. Not by the same people, but also related to the topic of learning 3D programming. Shadertoy is a web application that lets you play with shaders in C++ inside a web IDE that can be updated on-the-fly. It takes a bit of CPU and graphics horsepower to run comfortably, but if you’ve got the capacity, it’s worth browsing the demos on the site just to see the cool stuff you can create with it. This tool was created by Íñigo Quílez, who also has a really cool home page with lots of tutorials and whitepapers. If you like demoscene stuff, then definitely check it out.

Another neat find that I only recently discovered goes by the name of Rosetta Code. It bills itself as a programming chrestomathy site, which basically means that it’s a way to learn how programming languages are related in a comparative way. There is a large directory of different programming tasks, and each task page lists ways to implement a solution in a wide variety of languages. It’s a wiki, so not every page has every language implementation, but there’s obviously a ton of work put into the site, and most tasks have implementation in the major languages. Really fascinating and useful at the same time.

Finally, there’s The Nature of Code. This site hosts a free e-book download of the content, and provides a link to purchase a dead tree version if you wish. Here’s how the website describes the book:

How can we capture the unpredictable evolutionary and emergent properties of nature in software? How can understanding the mathematical principles behind our physical world help us to create digital worlds? This book focuses on the programming strategies and techniques behind computer simulations of natural systems using Processing.

That sounds right up my alley. I haven’t read the book yet, but I have skimmed it a bit, and it looks like the kind of things that I love: non-linear systems, physics simulations, fractals, and the like. When things settle down here a bit, I may tackle the book and re-write the sample code into Python. That would give me some more Python practice and force me to really think about the algorithms behind the text, not just blindly copying, pasting, and executing the scripts.

Let me know in the comments if you found any of these links useful or fascinating, or better yet if you know of other links in the same vein.

New Miles-Per-Watt Record Opportunity?

If you regularly follow science news, you may have heard of the Breakthrough Starshot initiative. In short, this is a study to create pathfinding technology that would allow the eventual launch of micro-lightsails with tiny mass to the Alpha Centauri system at a significant velocity (0.2c!) with a ground-based laser array. It’s probably a serious effort, as it is being privately funded to the tune of a whopping $100,000,000. No doubt, an extremely audacious undertaking.

Sounds interesting, but what does this have to do with radio? Well, obviously there’s the issue of how you can get a usable signal back to Earth across a distance of 4-and-a-half lightyears from a craft that masses in 10s of grams. I was wondering about that exact engineering challenge when I came across this article in my feed reader today. It turns out that someone has studied how one might use the Sun as a gravitational lens for lightwave communication across interstellar distances. Claudio Maccone, an Italian physicist, has run an analysis and has determined that putting a receiver at distance of at least 550 AU from Sol will give the desired lensing effect for optical communications.

Speaking before Maccone at the Breakthrough Discuss meeting, Slava Turyshev (Caltech) pointed out that the gain for optical radiation through a FOCAL mission is 1011, a gain that oscillates but increases as you go further from the lens. This gives us the opportunity to consider multi-pixel imaging of exoplanets before we ever send missions to them.

That’s kind of amazing. Maccone calculates that the bit error rate of optical communication from at any significant distance from Sol quickly degrades to around 0.5. However, by using the Sun as a lens, the BER stays at 0 out to a distance of 9 LY. Here is a graph of the effect of standard comms and those enhanced by using the Sun as a gravitational lens, as calculated by Maccone:

fig024

What’s really crazy is this next paragraph:

But as Maccone told the crowd at Stanford, we do much better still if we set up a bridge with not one but two FOCAL missions. Put one at the gravitational lens of the Sun, the other at the lens of the other star. At this point, things get wild. The minimum transmitted power drops to less than 10-4 watts. You’re reading that right — one-tenth of a milliwatt is enough to create error-free communications between the Sun and Alpha Centauri through two FOCAL antennas. Maccone’s paper assumes two 12-meter FOCAL antennas. StarShot envisions using its somewhat smaller sail as the antenna, a goal given impetus by these numbers.

So that would have to rate as the ultimate QRP DX, eh? I’m not sure how realistic any of this is, but I’m pretty sure the physics are well-established by now. Kind of makes the Elser-Mathes Cup look like small potatoes.

 

Etherkit, Microcontrollers

200,000 Miles Per Watt

If you wouldn’t mind, I would like to draw your attention to my latest post on the Etherkit App Notes blog. In it, I detail how to create a 10 milliwatt WSPR beacon using nothing more than the Etherkit Si5351A Breakout Board, an Internet-connected PC, and a low-pass filter. A simple project, but one that gives quite a bit of fun testing the ionosphere given the cost and complexity.

Selection_104

I don’t want to take away from the post, so I will advise you to go there to read it, but the bottom line is that with about 10 mW, I was able to get a signal decoded over 2000 miles away. I remember reading the old exploits of the QRPp gang in books like QRP Power, where you had to be really dedicated, organized, and good at decoding CW in the worst conditions. Now, we have the luxury of a mode like WSPR, which lets us do milliwatt propagation experiments without breaking a sweat.

One idle thought I had about this is whether it would be feasible to put this transmitter on the 13 MHz HiFER band (check out Dave AA7EE’s excellent treatment on the matter) and whether that would be something that would be fun and useful for schoolkids to experiment with. Of course, it’s technically feasible, but I would want to be sure that 1) it’s legal and 2) there would be interest in doing it. A single PCB could be made with one Si5351A output attenuated to around 4.6 mW and low-pass filtered for transmit, while another output could be used to drive a simple fixed-frequency receiver based on the SA612. Let me know what you think about this in the comments.

Etherkit

Si5351A Breakout Board TCXO Upgrade

I’m pleased to announce an upgrade to the Etherkit Si5351A Breakout Board with TCXO reference oscillator. In boards manufactured previous to today (and the ones kitted in the initial crowdfunded initiative), the TCXO used was a Fox FOX924B-25.000. It worked well and did the job it was supposed to, but has one flaw in certain situations. The compensation loop in this particular TCXO has relatively wide frequency adjustment steps that can become obvious when using the Si5351A Breakout Board in a very narrow band mode such as QRSS. Here is a screen capture from Argo showing the behavior of the Si5351A Breakout Board with the Fox TCXO when outputting a carrier on 28 MHz, from a cold start.

Fox FOX925B-25.000
Fox FOX925B-25.000

As you can see, as the TCXO is stabilizing to operating temperature, the compensation circuit adjusts the frequency in relative course steps of around 3 Hz or so. Once the TCXO is warmed up, it jumps around less often, but still does occasionally have to frequency correct, and does so in a jump of similar size. This TCXO is still fine for most other uses, such as a VFO for a SSB/CW radio, but doesn’t work so great for the MEPT modes, especially on the upper frequency range of the Si5351.

In the course of developing OpenBeacon 2, I determined that I would need to find a more suitable TCXO to use with the Si5351. After trying about five different oscillators, I finally found a fantastic substitute, and it only costs a bit more than the Fox TCXO. The Abracon ASTX-H11-25.000MHZ-T comes in a smaller package than the Fox FOX924B-25.000, but it will still fit on the footprint for X1 on the Si5351A Breakout Board. Here you can see the same test as above run for the Abracon TCXO.

Abracon ASTX-H11-25.000M
Abracon ASTX-H11-25.000M

It seems to find a stable frequency very quickly, and more importantly you can see that the compensation loop seems much tighter, with frequency corrections coming much faster and in smaller increments. You can only barely see a bit of fuzz from the frequency corrections on this low-bandwidth plot. This is much, much better for the MEPT modes.

As of today, all of the Si5351A Breakout Boards with TCXO option sold in the Etherkit store will have the Abracon TCXO, and the price will stay the same at $15.

Etherkit, Homebrewing, Microcontrollers, QRP, Wideband Transmission

Wideband Transmission #6

Happy New Year 2015!

2014 was a bit of a mixed bag here. It’s been a transition year for Etherkit, as I reorganize and reorient the business for a renewed push to get the CC1 and other new products to market. I believe that good things are beginning to happen there.

On a personal level, my two boys have been doing fantastic. Noah started preschool and is really enjoying it. Eli is at a bit of a difficult age (the Terrible Twos) and is between baby and little kid, but he’s got an amazing personality and is growing up so quickly. Jennifer and I celebrated five years of marriage and 11 years since our first date! Things haven’t been perfect in the extended parts of our families, but at least in our household we’ve all been pretty healthy and have been able to enjoy many blessings.

Si5351A Breakout Board Campaign

There have been a fair number of neat projects I’ve seen using the Si5351A Breakout Board that I posted on OSHPark, along with my Si5351 Arduino library, which is absolutely wonderful. However, I realize that it’s a pain to order PCBs and all of the parts separately, and that a kit or a finished board would be ideal.

I’ve decided to try something new in order to bring the Si5351A Breakout Board kit to market: we’re going to try crowdfunding the first batch of kits. I’m going to set a modest goal to trigger the funding, but all orders will be welcome over the goal amount. In fact, I intend to set a stretch goal at some higher funding level to devote a certain number of hours to improving the Si5351 Arduino library, including:

  • Add tuning from 8 kHz to 1 MHz
  • Add tuning from 150 MHz to 160 MHz
  • Fix the bug that does not allow output over 125 MHz
  • Implement access to the phase register
  • Implement sub-Hz tuning for modes like WSPR
  • Other bug fixes

I also intend on lowering the BOM cost by removing the broadband output transformers, and offering multiple variants of the kit, including the option to add SMA connectors and a TCXO. I’m composing the campaign on Indiegogo right now, and I’m shooting for a launch in about 10 days. I’m hoping to gain experience with this campaign with the goal of using it to fund CC1 kitting later in the year.

Why am I telling you this now? Because I would like to let those of you are are interested in purchasing one (or otherwise interested in supporing Etherkit) get advance notice so that you can order on the first day that the campaign goes live. This will help to give the campaign more momentum and perhaps help to spread the word further. I will be sure to make a blog post here when the campaign goes live and tweet about it as well, so keep an eye on those channels if this is something that intrigues you.

Simple WSPR Transceiver using Si5351A

I came across this simple WSPR transceiver from KC3XM driven by one of my Si5351A Breakout Boards via @wm6h and Dangerous Prototypes. The WSPR transmitter is simply a BS170 driven by one of the Si5351 outputs, which is buffered by a logic gate and keyed by a standard PNP keying switch. Control of the Si5351 and keying of the transmitter is performed by a plain vanilla Arduino Uno (the code has been posted to GitHub).

This looked so simple to build that I had to give it a try. I quickly built up the transmitter portion, tacked on a 10 meter LPF (the original version is for 30 meters), modified the code for my callsign and grid, and changed the Si5351 output frequency to the 10 meter band. The transmitter put out nearly exactly 1 watt of RF (with only about 1.2 watts of DC input total) into 50 ohms and ran quite cool. Hooked up to my Moxon, it had no problem generating spots when pointed east and started on an even minute so as to properly synchronize. Fun stuff!

Generating PSK with an Arduino

If you haven’t been following the blog of KO7M, you should be. Jeff has been doing a lot of experimentation with with NB6M and other home experimenters in Washington state, especially with stuff like the Minima and using microcontrollers in ham radio projects.

Lately, Jeff has been working on getting an Arduino to output PSK audio. He has a series of recent posts about it, but these two are probably the most important. The character timing is not quite right yet, but the basics of how to generate PSK via PWM audio signals are here. Good stuff!

Si5351 and Raspberry Pi

Another really great homebrewer blog is M0XPD’s Shack Nasties (oh you Brits and your silly names) blog. Paul has been doing a lot of work with the Si5351 as well, and his latest post about the Si5351 is details of how he interfaced it with the Raspberry Pi. Excellent information to have, as the RPi is of course much more powerful than your garden variety Arduino.

Etherkit, Random Musings

Etherkit Rev B

You may have already seen it, but please allow me to direct your attention to my latest post on the Etherkit blog. For the tl;dr version: sorry to have been quiet on the business front so long, also sorry to have failed to do a good job keeping up on business communications, the OpenBeacon and CRX1 products are being sunsetted (I’ve reduced the price of my limited remaining stock of OpenBeacon to $29), new products and new initiatives are coming in the near future.

I wanted to mention a few more things that I neglected to say in that post. First, I also plan on releasing another revision of the Si5351A Breakout Board for sale as a kit. There are a few bugs to fix on the current version on OSHPark, but it shouldn’t take me too long to get a new revision up there and ready for testing soon. I’ve also reduced the price of EtherProg to only $9, which should make it in line with other similar tools.

To be bluntly honest, it has been a difficult year here on the Etherkit front because of multiple failures, some of which I must keep private for now. However, I have been buoyed by encouragement and help from friends and family, and I plan to redouble my efforts to make Etherkit the company that I envisioned when I founded it.

There will still be quite a bit more to announce in the near future, but now is not quite the time to reveal everything being worked on behind the scenes here. I will have more Etherkit news soon, so as usual, watch this blog for updates.

Thank you!