Offboard coprocessor!

[Ben Englert]

I am hell-bent on using an offboard coprocessor with the FRC next year because I'm sick of lookup tables that need to be regenerated every time hardware changes (although perl does expedite that process).

I've read the documentation for the Gumstix series of Linux single-board computers, as well as all of the Adambots' "Delta Force Coprocessor" material, and the FIRST rules regarding custom circuitry. I am about ready to take home an RC and order a Gumstix and get going.

I'm just wondering if anyone has any experience with this that they'd like to share.

[mogunus]

Originally Posted by Ben Englert

I am hell-bent on using an offboard coprocessor with the FRC next year because I'm sick of lookup tables that need to be regenerated every time hardware changes (although perl does expedite that process).

I've read the documentation for the Gumstix series of Linux single-board computers, as well as all of the Adambots' "Delta Force Coprocessor" material, and the FIRST rules regarding custom circuitry. I am about ready to take home an RC and order a Gumstix and get going.

I'm just wondering if anyone has any experience with this that they'd like to share.

I used a gumstix to do binocular vision this year. They're AWESOME, and they work great. I'm putting together a wiki page on the gumstix tikiwiki, explaining everything, and I'll have my code up on their subversion repository soon. I'm also developing a wifi positioning system, using gumstix. All that info will be there too.

[Mike]

Unless you're really doing some hardcore stuff, I don't think a gumstix is necessary. Look at the Atmel AVR series, specifically the ATMegas. An STK500 development kit can be had for $80 and includes everything to get started. Someone likened it to a Swiss Army knife for microcontrollers, and I agree.

Atmel STK500

[coldabert]

I would love to know what sort of programming you have that requires that much additional circuitry and time. Dont forget rules about using items from previous years, you wouldnt want to have it rejected by inspectors after that much. Not to mention the costs of development hardware.

[Joel J]

There is a $50.00 demo board from microchip that actually includes the 18f8722.. its fairily small, and very useful..

http://microchip.com/stellent/idcplg...&part=DM183022

[Greg Marra]

Don't forget, those EDUBot controllers run pretty much the same hardware as the pre-06 RCs. They can be hooked up in parallel to your main RC to do some computations.

[Dave Flowerday]

Originally Posted by Greg Marra

Don't forget, those EDUBot controllers run pretty much the same hardware as the pre-06 RCs. They can be hooked up in parallel to your main RC to do some computations.

...except that the EDU-rc is illegal for use in FRC competitions, since it is a COTS electronic item costing more than $200.

[Greg Marra]

Originally Posted by Dave Flowerday

...except that the EDU-rc is illegal for use in FRC competitions, since it is a COTS electronic item costing more than $200.

Whoops. I take that back .

[Billfred]

So is there any way to hack a Vex controller? At $149.99, they're suddenly legal under every rule I could find (provided you powered them legally).

[devicenull]

Originally Posted by Billfred

So is there any way to hack a Vex controller? At $149.99, they're suddenly legal under every rule I could find (provided you powered them legally).

Sure.. it's basically the same code running on the normal RC.. but it's the 8520, so you aren't gaining that much power for what you would have to do to interface with it.

[Ben Englert]

Originally Posted by mogunus

I used a gumstix to do binocular vision this year. They're AWESOME, and they work great. I'm putting together a wiki page on the gumstix tikiwiki, explaining everything, and I'll have my code up on their subversion repository soon. I'm also developing a wifi positioning system, using gumstix. All that info will be there too.

Am looking forward to seeing that - I'm already in contact with the Adambots who are successfully using a Gumstix this year, and they have pointed me to their SVN repository as well. Their programmer mentioned that it would be really cool to have all teams using this collaborate on it. I definitely agree!

Please do post us a link when you have one.

[ericand]

Team 1425 uses a PIC processor to controll the speed of the ball shooter this year. The shooter has two impeller wheels that give the ball its velocity. Our aiming depends on the shooter having a constant velocity as close to the limit as possible.

The PIC processor uses digital I/O to provide 2 bits of info for each impeller. The code on the robot controller uses 3 of the 4 possible
combinations to tell if the impeller is {too slow, on speed, too fast}

The robot controller uses this info to determine if/how to adjust the PWMs controlling the impeller motors.

[Doug G]

Originally Posted by ericand

Team 1425 uses a PIC processor to controll the speed of the ball shooter this year. The shooter has two impeller wheels that give the ball its velocity. Our aiming depends on the shooter having a constant velocity as close to the limit as possible.

The PIC processor uses digital I/O to provide 2 bits of info for each impeller. The code on the robot controller uses 3 of the 4 possible
combinations to tell if the impeller is {too slow, on speed, too fast}

The robot controller uses this info to determine if/how to adjust the PWMs controlling the impeller motors.

We do the same thing with our shooter, but just simply use a couple of encoders connected to the RC and Watson's velocity PID code with some tweaking of the constants and are getting pretty good results. So why use the separate PIC?

[Gdeaver]

I'm curious as to why there is a need for a powerful coprocessor. I can see using a small PIC for a sensor that requires I2Cc or SPI interface since we don't have access to the hardware on the robot controller. This year the camera certainly didn't overwhelm the processor. There are more limitations in the actual camera hardware and firmware. So why the need for a powerful
coproc? Are our games complex enough to justify one?

[fowlerm]

We are using a 400MHz Gumstix running Windows CE 5 for our drivetrain/positioning system and target acquisition, but we didn't have it on the robot at UCF. It will certainly be there for Nationals.