So, after extolling all of the electronic virtues of the v0.3 Kit PCB only a few days ago, I’ve gone ahead and created a new revision of the board already. It turns out that it can indeed be smaller, without sacrificing any of the existing functionality. In fact, v0.4 is a full 25% smaller even than v0.3, giving us a PCB that is now a mere 46% of the original v0.1 board’s size.
I’ve just sent in the order for this board, so I won’t have it in my hands for another two weeks or so. In the mean time, I can definitely work with the v0.3 board I’ve got built so far. Functionally they are pretty much identical. Here’s an image that shows the progression in size reduction from v0.1 up through v0.4:
It’s pretty remarkable, really. The v0.4 board will be much more comfortable on the back of the hand. I’ve kept much of the same layout, but moved a couple of the modules over to the right side of the Teensy++ board, so that the whole thing can be about 0.1″ narrower and over half an inch shorter. There’s a kind of “double wing” visual effect now, since the various modules now hang off both sides of the board. Although this would never do for a commercial retail product, it is very valuable for the kit version, since it allows the very rigid PCB that actually sits on your hand to be as small as possible. And this time, I really this it is just about as small as possible. There is almost nothing left to rearrange, and doing so at all would require modifying the WT12 module’s GPIO pins, which I’m not planning to do since it would make that board much less simple to prototype with on its own.
Switching to the MPU-6050
I’m also now officially switching to SparkFun’s new MPU-6050 breakout board instead of using their 6DOF IMU combo breakout board. Both modules have an accelerometer and gyroscope, but the MPU-6050 does it in a single module, faster, more accurately, with no potential axis alignment issues, with a powerful DMP, for $25 less. What’s not to like?
The v0.4 board still has a dedicated header for the 6DOF IMU board, and the embedded software will continue to have support for both, but it is probably best to get the MPU-6050 board instead if you’re looking to build your own prototype and you don’t already have a 6DOF module. It’s just a better option all around, and saving a whole $25 just like that on the overall cost of the kit is pretty significant, especially with the added benefits of future DMP usage (which is close, but still not functionally useful for the Keyglove just yet).
Next up is fixing the ATTiny44-based feedback module. I still haven’t managed that, but this v0.4 revision kind of took me by surprise when I started tinkering with the possibility. Ah, the lure of optimization…
Great progress! Keep it going. Looking forward to the next installment
OSH Park won’t allow holes within 15 mils of the board edge, but maybe they could be cnecinvod to look the other way. I tried what you did above too and had a flap of copper left on each hole, which I suppose is slightly better, but still not good enough.