Hypomnemata

TI recently announced a new entry in the hobbyist microcontroller space, the TI LaunchPad, which is targeted at the Arduino market.  I don’t believe it’s going to make much of a dent, though.  I spent a while looking at the LaunchPad. I like the idea of it, and I love that TI is doing something to make devices cheaper and therefore more accessible (which is why I built the Breaduino and Volksduino kits, low-cost, accessible Arduino clones). After my initial excitement, though, I’m feeling pretty negative about the device’s future.

(Shameless plug: order the Volksduino kit for $20!)

The kit is a $4.30 purchase, which sounds great, until you find out what’s in it: everything.  Not great, but incredible!  It’s got a USB programmer, a couple of MSP430 Value Line microcontrollers, the development environments.  It even includes the USB cable, and comes in a nice box.  The website has an unboxing video, which is … odd, for a uC dev kit.  Overall, this is a fantastic value, and a wonderful development kit.  If the IDEs are remotely friendly, it makes a compelling first device.

First off, they must be taking a loss on every one of these. I priced out building a knock-off of just the carrier board (without all the control electronics, though with a regulator). I can’t do a kit for less than $4.50*, not including the actual MSP430 chips.  True, they’re using all their own parts, so it’s probably not more than $6 a board, but, still, it’s impossible for anyone but TI to make the main board with their pricing.  This locks up the core of the ecosystem, but might be okay: people can make stations (what I’m calling “shields” for this board).

Judging from the photos, the footprint is 2″x2″, with the header rows at 1.8″ apart. This is just a tad larger than the little Radio Shack protoboards, but not small enough to make the larger protoboards look “at home” docked to the top of it. Their pin layout is suitable for doing stations, but it’s teensy. The Arduino shield footprint is annoyingly small, and this thing is smaller still. And, of course, these microcontrollers have a lot fewer GPIO and analog inputs  than the Atmegas, so you can’t do a useful station-shield adapter board. Beyond that, it looks to be 3.3V only; ask Sparkfun how popular 3.3V Arduinos are vs their 5V siblings.  Overall, I don’t find it terribly friendly to kit work.

TI is going to move a ton of these devkits, but I don’t see it developing into an ecosystem like the Arduino’s. Kitmakers are going to feel the “cheap cheap cheap!” pressure, and it’s going to be really hard to escape that.

(That said, I have a design for the “ProtoStation” already done. I just need to get my mitts on a copy of the board to double-check my schematic before I send it off to the board house. Hopefully people are willing to spend another $3~10 on their new ultra-cheap toys.)

* NB: TI hasn’t published application notes for that uC, nor a reference schematic in the datasheet, so my design estimate is ballpark, within a quarter or so.

Want to learn how to repair circuit boards?

Did you make a PCB, only to find out that the design is wrong?

Green wires to the rescue! “Green wires,” aka “patch wires,” are the fixups made after-the-fact, completing connections and adding components. It’s the last (and mostly hidden) step in circuit design: schematic, board, green wires. There’s a lot of art to green wiring, but you can learn the fundamentals in a couple of hours, hands-on.

Conveniently enough, I’ll be running a 2 hour, hands-on workshop on green wiring on Saturday, July 10th! The cost is $25, which includes an Arduino clone kit that needs several kinds of fixes. We’ll talk about diagnosing potential problems on a circuit board, then walk through techniques for fixing them on a kit I’m developing. At the end,
you’ll have new tricks for fixing boards, as well as a better understanding of the board design process (and a shield-compatible Arduino clone to play with).

This is a slightly advanced workshop, so you should be comfortable with a couple of things:

* soldering: we’re going to do a fair bit of this (building a kit)
* reading schematics: you should be able to read basic schematics

If you’d like to come, please let me know, so I know how many kits to bring. And, if you pay by PayPal before July 4, it’s only $20:

Register for the green wire workshop! (Workshop has happened, look for a re-run at a future date!)

What:

Green wire workshop (PCB fix-up)

When:

Saturday, July 10th, 1PM

Where:

Noisebridge
2169 Mission St (at 18th)
SF CA 94110

BART: 16th and Mission

Cost:

$20 before July 4, $25 thereafter (materials included)

Noisebridge is an open workspace, so the environment may be a bit chaotic.

10% of the money I collect will be donated to Noisebridge, to ensure we continue to have it as an excellent resource.

What we’ll cover:

* The construction of a PCB
* Identifying faults (shorts, opens, and oopsies)
* Basic strategies for dealing with the above
* Hands-on practice fixing each of the above

No one turned away for lack of funds. Drop me an email in advance, and we’ll work something out. I’d love to have you there!

I’m now selling my first kit! The Breaduino is a $10 Arduino clone you build from scratch. Unlike most kits, there’s no circuit board: you provide a breadboard (even the teensy half-length ones will work), and build your own Arduino from scratch.

I’m really excited about the prospects for this kit. It’s perfect for a classroom setting, which is a big deal to me. Any electronics classroom has everything you need to build this, and it can run off a 9V when completed, letting everyone start their kit up, instead of taking turns on the bench supply. More importantly, students can see exactly how it’s hooked up: it’s pretty darned simple. As an instructor, you can easily explain the purpose of every component during assembly, and still have a classroom of the things assembled in a half-hour session. I’d love it if these made their way into classrooms (email me for educational discounts). At $10/each, the Breaduino kit is also pretty easy in terms of materials fees. Students will also need a 9V clip ($0.10) and a breadboard ($8 for something nice at Adafruit), so, for $20 apiece, they can take home their handiwork.

It’s also great for those of us who work on Arduino-powered art pieces and gizmos. Dropping a Duemilanove ($30) into a project is a commitment, especially when the rest of it is made from free-to-you scavenged parts. This kit is designed for a breadboard, but it’s totally amenable to solder-down protoboard for permanent installation. You can do all your prototyping on a breadboard with a Breaduino, then transfer it exactly as-is to a protoboard. It’s also really small-footprint, so you can use a board only a fraction larger than the Atmega328 chip itself. The only way to get appreciably smaller is to go surface mount (but that kit’s a ways off). I’m hoping to do cheaper soon, too, by removing a few components from this kit.

Building the Breaduino kit has been interesting. It’s been almost entirely a matter of documentation: putting together an Arduino clone is fantastically straightforward. Between Atmel doing a fantastic job of making an easy-to-use microcontroller and the clear schematics from the Arduino team, it went together quickly. After that, there was a bit of work putting together a bill of materials, and a big order from Mouser. Then I had to document it. And make a video. And a website. And then redo a bunch of that, because it looked awful. Finally, all that work was done, and it came time to bag up kits. Oh, wait, I need a sticker design, and and and…

Happily, a lot of that work was in learning. I’ve now learned a lot, and will have a few more kits coming out soon: a 48-input analog input shield, another couple of different low-cost Arduino clones, and, eventually, the project that kicked all this off: a near-space ballooning shield. I’ve got a handful more ideas for things, too: a benchtop power supply with LCD readout powered by an Atmega, the ever-popular automatic bike lights, a plug-and-play relay board, an RFID appliance shield, an all-surface-mount Arduino clone… That said, I’d love more ideas. I’d love any kit suggestions people might have, leave a comment!