On 1/15/07, Arnar Birgisson <arnarbi@gmail.com> wrote:
Hello all and thank you Jesse for an excellent response!

On 1/15/07, Jesse Welling <jesse.welling@gmail.com> wrote:
> > What I want to do is have a wifi enabled computer onboard a r/c
> > helicpoter connected to a usb webcam. I'm a bit confused about what
> > expansion boards and/or motherboards I would need.
>
> Currently all Gumstix can be USB  devices only, not USB masters (which is
> what would be needed)
> You might want to check out some serial cameras though.
> http://www.jrobot.net/Projects/AVRcam.html
> http://www.electronics123.com/s.nl/it.A/id.2027/.f?sc=8&category=241

This one looks promising, esp. with the 2.2 mm lens (118 fov!). 115.2
Kbps is ok with the gumstix?
Should be fine but I have heard that most of those cameras with huge angles have no IR filter, which means some colors might look funny but wasn't explained very well to me so (^^;)

> http://www.acroname.com/robotics/parts/R245-CMUCAM2-PLUS.html
> if you have some time to kill (who does?) the new pxa270 based gumstix might
> come by the time you are ready to buy.
> IIRC they have USB host capability
>
> > I also like the robostix, and would like to be able to control some of
> > the servos on the helicopter - so if possible I'd like the option of
> > adding a robostix to the computer.
>
> This would be your best bet to control the helicopter. But you only get 6
> servo channels
> Another option would be a serial servo controller like this one:
> http://www.pololu.com/products/pololu/0207/
> And if you needed more than that I think there are some 16 channel ones out
> there.

My helicopter uses 5 channels, I believe that is usually the case for
r/c helis (throttle, collective, tail/gyro and cyclic x and y). So - I
should be ok with the robostix.

sounds good.

> > If possible, I'd also like to be able to add the GPStix - but I'm a
> > bit confused about what expansion boards go together and which don't.
> > Am I correct that the GPStix requires a stuart for example? Could I
> > connect both a wifi-stix and gpstix to the same motherboard?
>
> Only one 60 pin and one 92 pin board will fit on a connex gumstix.
> What this means is that you have a some options.
> here are some outlined for you (i'm sure there are more)
>
> 1. Wifi/connex/GPStix + serial servo control board
> 2. Wifi/connex/robostix +
> http://www.u-blox.com/products/rcb_4h.html (this is the
> same GPS that the GPStix uses)
> 3. Wifi/connex/GPStix + robostix over i2c ( E.G. not using the 60 pin header
> but using the i2c buss from the GPStix and connecting it to the robostix)
>
> the third and second option provide the most flexibility because you can
> latter expand the robostix using the a2d and accelerometers and other IMU
> devices
> for more precise control. Check here for some good sensors:
> http://www.sparkfun.com/commerce/categories.php?cPath=23_120
> http://www.sparkfun.com/commerce/categories.php?cPath=23_80
> http://www.sparkfun.com/commerce/categories.php?cPath=23_85

Ok, I like no. 3 - do you have any more info on that (links or such)?
The GPStix has 4 a/d convertors - would I be able to use those to run
servos in addition to the ones on the robostix at the same time?

a/d doesn't run servo's it just takes measuments (analog to digital), so if you wanted to have an auto hover, or a flight recorder, or an autonomous pilot you would need those kind of instruments.

How much advantage does a 400mHz cpu hold over a 200MHz one in this
situation? I was thinking about the robostix-wifi pack and the GPStix
in addition. Would that fit option 3 above?

I would go with the 400mHz connex without bluetooth. This should give you extra processing power should you choose to use it. but if you choose to go with the 200xm you might want to look at this pack http://www.gumstix.com/store/catalog/product_info.php?products_id=174 and should you choose to use GPStix and serial servo controller you will have enough serial ports with out getting rid of a serial terminal (although you might not need it with the wifi it's good to have for back up.

One last question - for the GPStix, do I need a Stuart board?

It's always a good idea to have some way to get a serial terminal, so either a tweener or a waysmall board will allow you to get into the boot loader should something go wrong with linux on load. other wise you can use a serial addapter hooked to your robostix (5v TTL serial to 12v RS-232 serial) to get a serial terminal incase the wifi isn't working. Here is the serial converter I use, it's pin compatable so it's easy to hook up. http://www.acroname.com/robotics/parts/S13-SERIAL-INT-CONN.html

> Hope this helped

Yes indeed, thank you very much.

Also you might want to check out the wiki...it has alot of answers there. http://docwiki.gumstix.org/Main_Page but the wiki search is a little wonky so I use google to search it instead.
Another good place for info is http://dir.gmane.org/gmane.linux.distributions.gumstix.general it has a record of everthing that has ever been discussed on this mailing list. every single problem any one has ever asked about is there so I'd look there if the wiki doesn't turn up any thing.

Arnar

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