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Parallax Insider News

Wireless Programming and Propeller Activity Board WX: Software and hardware developers are making big progress!

  • By: Ken Gracey Published: 26 January, 2015 11 comments

A customer on the forums asked about our progress on wireless programming progress for the Propeller. It’s been possible to program a Propeller over WiFi and XBee 802.15.4 RF links for quite some time, but it requires new programming tools and hardware designs to make this really beneficial for our customers. It’s the perfect demonstration of engineering - 90% of the fun is making a prototype work, but 90% of the work is bringing it to the market.

Educators have limited time in the classroom environment and need the tools to work perfectly every time, so we will release the hardware and software when it passes all of our tests.

Our goal is that students will be able to program our BASIC Stamp and Propeller robots (Boe-Bot, ActivityBot, Arlo, S3) from Chromebooks (WiFi and USB), Android-OS tablets (WiFi and USB) and iPads (over WiFi).

Propeller Activity Board WX - WiFi Programming Hardware

The Propeller Activity Board WX will provide a fully-wired, preset WiFi programming interface for our ActivityBot. On January 26, 2015, we sent the latest revision of the Propeller Activity Board WX printed circuit board to fabrication. The WX auto-selects the WiFi or USB programming port - whichever one is providing the program. The WX will have a new Parallax part number and be offered concurrently with the Propeller Activity Board Revision C. Educators and students can count on having this hardware by the Fall 2015 school semester.

Take a look at the pictures above to see the prototype WiFi programming circuit on top of a Propeller QuickStart Board, along with the layout of the new Propeller Activity Board WX.

BASIC Stamp Board of Education WX

This Board of Education (BoE) will be next up for a much-needed revision for wireless programming. We are in the process of deciding what we’ll be adding to the very popular BoE. The kinds of features we’re considering are an XBee socket (for WiFi programming and general RF communication), USB power, and an A/D converter. Tell us what you’d like to see on the next revision of the Board of Education by posting a reply below.

What about the software?

Our iOS programming tools are now working for iPad - with Spin language support only. We’re considering using a remote server for compiling C code for the ActivityBot, as it’s proven quite complex to put GCC on the iPad. We expect a Spin-only release before Summer 2015, with a C version shortly thereafter.

For the Chromebook and any Android tablet running Chrome, we’ve just started development of a Chrome App to allow USB and WiFi programming of the BASIC Stamp and Propeller. For this project we’ve formed an agreement with Iced Dev, a coding startup who understands our needs and has experience with programming other devices from a Chrome App. Schedule is still being determined for this software, but we expect beta versions available by summer.

All of the hardware and software will be completely open source.

We expect that teachers and students can simply plug our systems into their courses and let their student’s enthusiasm take over because the whole system of software, tutorials and hardware will work perfectly together!

Ken Gracey, CEO


I am a professor at Jackson State University in Mississippi and I teach robotics using the ActivityBot. All my students have ipads, and I will welcome C programming via the ipads. It will open a new arena of applications and interactive computing after hours

John Colonias, Ph.D.

Dr. Colonias, 

The Propeller Activity Board WX could also provide a platform for a series of tutorials and applications around Internet of Things - connecting sensors and tablets to microcontrollers. With the new WX board I think you might be interested in Parallax putting effort into IoT curriculum. Would this be of interest to you?

- Ken Gracey

It's important that we meet your needs with our efforts, so we value the feedback. I agree - it could help speed learning if the students could take the hardware home for assignments, programmed from their iPads and return to class for more demonstration-type and advanced application activities.  

Would help to know if many of your students are using Chromebooks, too.  

Ken Gracey
Parallax Inc. 

This is great news Ken. This will open up all sorts of possibilities. The students at our school are so comfortable with their iPads - This will give them a great "way in" for our projects! I can't remember, is the a goal for the S3 also?

Hey Whit+

The S3 interface is entirely iPad at the moment, at least for the GUI and programming interface which is via WiFi. However, we expect that our Chrome App efforts will open up the S3 for anything that runs Chrome. In summary, we've got two horses in the race right now: a fantastic developer from Poland who's working with us on the iPad efforts, and a domestic startup for the Chrome efforts. Both should come to completion for the S3, but the iPad is our initial focus for that robot. 

Ken Gracey
Parallax Inc. 

That sounds fantastic Ken. At the moment, do you have in mind or a rough guess on how much the new Propeller Activity Board WX will cost per unit? And will they be available for purchase as an individual product
or will they only be sold in an Activity Bot kit.

Kind regards.

Coolio Ken!

Glad to see this concept making traction!
Naturally, I'll be looking for ways to twist this into doing my "prop" bidding without the requirement of a USB/Propplug!

Ln, price is the one question that will result in strict punishment from my colleagues if discussed in too much detail. Yet I love the question because it forces us to think about where we're headed. So let me back into it a bit and try to answer your question because we need to be thinking about this yesterday :)

You're going to want a really high-quality Made in the USA Propeller Activity Board WX board that "simply works all the time" with our software tools. We don't want to waste any of your precious hobby/education/engineering time with anything but a full system that integrates flawlessly (i.e., install software, connect to PCB quickly). You should be able to program the Propeller WX on an airplane without a cable, or on a robot in a class full of WX-enabled Activity Bots and so on. Providing such a system that works right is expensive. 

I'll start with the hardware. I suspect our bill of materials and labor to manufacture a Propeller WX board here in Rocklin are in excess of $35, but of course we'll try to optimize our manufacturing process to cut a few dollars through optimized pick-n-place and selective soldering processes. Putting all of our non-recurring engineering (NRE) design time aside (that's scoping out the design with our team, schematic and PCB layout) and supposing we granted ourselves the luxury of a Wal-Mart margin of 40%, we'd sell this at $59. But you'd agree we deserve more margin than Wal-Mart, as they just unpack a box from China and put it on a rack for 40% margin. In this case, the product is a result of our engineering creativity and a purchase of it represents an investment in one's self (you, the buyer).  

Therefore, based on bill of material costs alone it seems we'd have to charge more than $59 simply to be fair to ourselves, just looking at the hardware alone. 

But there's also software. For the past year, we've spent about $180K in development costs of software to support the Propeller WX. For this cost we were able to make two major achievements. First, our engineers had to evaluate the various WiFi modules available and choose one. Then, after we selected the XBee WiFi Module, we worked with Digi engineers to make a firmware upgrade to support our download needs (115K bps, 64K bytes) to load and verify a Propeller. And this had to be done like it would be over USB - no sloppy timing and full verification. This resulted in a portable code design that we can use in iOS, in Chrome Apps, OSx, or even Windows. 

Concurrent with this effort we developed an iPad application for putting our new tools to work. For this effort we worked with Mike Westerfield of ByteWorks.

If we apply the $180K of software development costs over the period of time in which we expect to get a return on our investment and assume each Propeller WX has to pay us back it's fair share of software development, we can calculate a per-board share of cost. In reality, there are robots and other uses of our work that will pay us back. But let's just say we want to sell 10,000 Propeller WX boards and recover our investment in two years - that's $18/board we can add to the cost. 

Therefore, our cost for a Propeller Activity Board WX is probably more like $35 (BOM and labor to build) + $18 (software costs) = $53/unit.

Bottom line: it's going to cost more than a Propeller Activity Board Revision C. Likely in the $79-89 range because $100 is just too high. We will need to consider other factors like our overall goals in education, marketing, and cost competition. Also, keep in mind that we only sell about half of our boards at this price - the rest go through distribution and we grant them a significant discount. The average selling price is much lower. 

For customers who can't afford the board due to excessive import costs (common in Asia and South America), they are welcome to build and sell their own from our files since the whole project will be entirely open.

Thanks for asking the question. Hope I didn't terrify you with more information than you wanted.

Ken Gracey   

Thank's Ken, For the well-educated answer. $79 - 89 range seems fair to me, and I can't wait to purchase the Propeller Activity Board WX.

Kind Regards

We've got our first Propeller Activity Board WiFi-ready (product name to be Propeller Activity Board WX) through the tests this past weekend. Jeff Martin, Sr. Software Engineer reports the following to me via e-mail (my apologies for formatting issues below which I don't have time to sort out):

"I've tested out the following so far.  For the most part, everything seems to work great.  Wherever issues were found, I note them in subbullets:

Connected an XBee Wi-Fi S6B module. (Passed)
I powered it up via a 7.5 VDC power supply (Passed)
(Problem) Unfortunately, the XBee activation label and green LED, as well as the Associate label and blue LED, are completely obscured by the power connector (see picture).  I think I had mentioned this in our meeting as a worry, but we each reasoned at the time that it wouldn't be obscured- we were wrong.  This seriously impairs their usefulness.  It appears that there may be enough room to move the XBee socket and associated components downward far enough to clear the power connector so that the labels and LEDs are clearly visible at all times.  I'm sure hoping that's possible.​

Noted PAB WX defaults to USB active LED. (Passed)
Activated the XBee's SoftAP feature via the Commissioning Button (pressing the PAB WX's Reset (RST) button 4 times briskly.  (Passed)  Yay!
Configured the XBee Wi-Fi via my smartphone to connect to my office's access point. (Passed)
Identified the PAB WX, via Wi-Fi, with my test software. (Passed)
Downloaded to the PAB WX via Wi-Fi. (Passed).  Yay!
(Problem) The blue DO LED is nice and bright, but the red DI LED is so dim that I had to shade the board to even realize it was lighting up at all.  I tried a separate test where I sent more serial data, but it stays very dim, almost imperceptibly lit.
Noted PAB WX switched to XBee active LED and stayed there. (Passed)
Disconnected the 7.5 VDC power supply and connected my computer's USB cable. (Passed)
Noted PAB WX defaults to USB active LED. (Passed)
Downloaded via Wi-Fi, noting that it switches to Wi-Fi active LED and stayed there (Passed)
Downloaded via USB, noting that it switches to USB active LED and stayed there (Passed)
Alternated between Wi-Fi and USB.  (Passed).  Yay!
Tried monitoring P16  (Failed)
A toggling signal on P16 does not seem to arrive on the SIG pin of the corresponding servo socket.
Tested Reset (RST) button multiple ways. (Passed).
Tested setting Wi-Fi module into SoftAP mode (via Reset button) and then resetting it to it's previous configuration by power cycling the board.  (Passed).

Now I'll start using it in various other ways also and will report the results."

There's a lot of engineering in this product and the prototype results are VERY encouraging (nicely done Jeff, David, Andy, Stephanie, Terrell, and everybody else!). We are currently making a few decisions about building out another 30 units for our external software team  and sending the PCB through another prototype run. Once the team decides what to do I'll let you know how the new schedule is shaping up.

Ken Gracey