Hi Mark,

> The PARTS (http://www.portlandrobotics.org/) folks are kibitzing around
> doing a robo-Magellan http://www.robothon.org/robothon/robo-magellan.php
> kit.  The design that folks are gravitating toward is to put together a
> platform that has a 6DOF IMU + 3 Axis Magnitometer + the typical robot
> related GPIO's and peripherals interfaced to a micro controller type of
> processor which is then interfaced via USB (full speed bulk) to a user
> provided USB host (laptop, Eee, OLPC, PC104, NSLU2...)
> I'm thinking we could join forces.

This is, as always, a great idea and we'd love to do it. But usually,
our avionics system ends up begin a little to do weird for use with a
on-land robotics system. Flying robots with rocket engines and wheeled
robots just end up having very different electrical systems :)

Our "generic" LPC2148 node was designed a year ago or so by a capstone
team. They did a great job, and the complete EAGLE schematics along with


Since then we've written some peripheral libraries for the LPC2148, but
unfortunately we haven't laid out the board yet. That's also on the
books for the next few months.

I think there's a lot to be shared with sensor design:

- Whatever GPS we end up using can certainly be shared, although it
might end up being too expensive for most robot use.

- The 3D magnetometer sensor can certainly be re-used.

- The IMU sensor design might be good thing to share as well. But our
dynamic range and bandwidth is WAY bigger than what most robots will need.

But, there are differences:

- We have a very specially power distribution system. Instead of using
the standard USB 5V supply, we directly distribute a 14.4V Li Ion
(probably polymer) battery pack, and have switching supplies on each
board. For justification for that, see the Capstone report.

- We're very concerned about volume and weight, which means small,
packed, four layer boards. Since we have some free use of Screaming
Circuits' facilities, we'll probably end up using > 2 layer boards with
enthusiast-inappropriate chip packages like uBGAs and such.

> What is the status of the LPC based IMU design and firmware?  Where is
> it documented on the PSAS pages?

The IMU in the planning stages right now. We'll probably pick the
sensors in the next two weeks (see http://psas.pdx.edu/SensorComparison/
), and begin the design shortly thereafter. All of the LPC nodes are
essentially vaporware right now, and we plan to fix that this winter :)

If PARTS picks the LPC2148, then I think there's *lots* to be shared
back and forth. It probably won't be board design, but I bet we could
share sensor design and a lot of low-level firmware.

I'm not sure what the PARTS timeline is like, but we hope to be done
with the generic node this spring and be working on sensor design
throughout the summer and have a complete package sometime later in
2008. If PARTS is in more of a rush than that, then we may be borrowing
designs from you, rather than vice versa :) But hopefully this is
something we can collaborate on!


Andrew Greenberg

Portland State Aerospace Society (http://psas.pdx.edu/)
[EMAIL PROTECTED]  P: 503.788.1343  C: 503.708.7711

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