Our progress towards a $79 UAV mod kit for toy RC blimps is going well. We've now got a much better, two-sided PCB board that we're having fabbed. It's smaller, has more features and now integrates the IR sensors on the same board (Eagle schematic here; mask files here)

The board is an Arduino (ATMega168 CPU) clone at heart (we call it "Blimpduino"), with:

--Four motor drivers (two 2-motor chips)
--Four IR sensors and associated supporting components
--Ground-based IR beacon
--A choice between rechageable (more expensive) and non-rechargeable (cheaper) Lithium batteries
--Port for Ping))) ultrasonic sensor
--ISCP and FTDI programing ports

Pretty cool--a complete blimp autopilot and sensor package (with one ground beacon) for $79! Don't place your orders yet--we've still got a lot of sourcing and testing still to come--but I'm looking at having it ready for Christmas ;-)

Views: 1138

Comment by Peter Klemperer on March 29, 2008 at 6:23am
Wow. This is a very neat project. Need beta testers?
Comment by Howard Gordon on March 29, 2008 at 7:34am
Looks good. The TSOP34856 is a compact package - smaller than the TSOP1738's I used. It does appear that the TSOP1738 had a wider field-of-view, though Mouser shows them as obsolete. Also, you might consider adding bypass capacitors across your motor outputs. You can put them on the motors, but it's easier to add them to the circuit board.

3D Robotics
Comment by Chris Anderson on March 29, 2008 at 9:04am
Howard,

Thanks for the comment. The RC blimps have the capacitors already installed on their motors, so we don't bother with them on our board.

What PCB design software do you use? I find the Eagle Lite really non-intuitive. (And its help file doesn't work on Vista--along with being pretty useless anyway)
Comment by Howard Gordon on March 29, 2008 at 9:14am
I use Eagle. I started with it last summer, and it took some time to learn, but I've designed 3 different boards with 1-2 revisions each, so it's making some sense now. The biggest problem I have is remembering which side of the board I'm currently on when adding or changing traces. There are lots of good tutorials, and I think the one from Cadsoft wasn't too bad.

http://www.instructables.com/id/Draw-Electronic-Schematics-with-CadSoft-EAGLE/
http://vulcan.ece.ucsb.edu/ece189/tutorials.html
http://www.sparkfun.com/commerce/present.php?p=BEE-8-EagleSchematic
http://www.pages.drexel.edu/~weg22/pcbDesign/pcbDesign.html

Also, I like the fact that I can run Eagle on my iMac with 20" screen - that makes a big difference.
Comment by Alasdair Allan on March 30, 2008 at 5:47am
Neat project, very impressed. It's basically an Arduino at heart, so maybe you should retain some easy access to the spare CPU pins? It looks like you're not using pins 23-28 on the CPU for anything (at the moment?). Perhaps you could expose those in a jumper block (in the same way as the Arduino) so that if someone wants to add a compass or a GPS at a later stage, it's easier..? I know you're trying to keep it under the magic US$100 mark, but it won't be a big incremental cost?

3D Robotics
Comment by Chris Anderson on March 30, 2008 at 9:31am
Alasdair,

You read my mind. I've been redesigning the board to add connector blocks for those extra pins so you add additional sensors. Just adds a few pennies to the cost, and won't change the final price..
Comment by Alasdair Allan on March 30, 2008 at 10:08am
Oh that's good! A GND and +5V pin would be nice too...? ;)

3D Robotics
Comment by Chris Anderson on March 30, 2008 at 10:16am
They're there already: the jumper is called "JP1"
Comment by Alasdair Allan on March 30, 2008 at 10:28am
So they are, oops!

3D Robotics
Comment by Chris Anderson on March 30, 2008 at 11:08am
Just to clarify, pins 23-28 are all dedicated analog inputs on the ATMega168 (see datasheet), so they would only be suitable for analog sensors such as touch or light. We only have one free digital I/0 pin, which I will make available for digital sensors or GPS.

If we go to a surface mount board, we can switch to the 32-pin version of the ATMega, which would free up some more I/O pins. That kit would cost a bit more (perhaps $99) since we'd have to ship the board in finished form. We'll see how much demand there is for that...

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