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Unread 28-01-2007, 15:55
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Kevin Watson Kevin Watson is offline
La Caņada High School
FRC #2429
Team Role: Mentor
 
Join Date: Jan 2002
Rookie Year: 2001
Location: La Caņada, California
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Re: Why use the RC to control Pan/Tilt

Quote:
Originally Posted by jgannon View Post
But c'mon... give the kid a break.
1) He's an engineer, not a kid.

2) My exchange with Joe is a year old. I'm going to have a talk with some CMU professors I know, because they clearly aren't piling on enough work if you have this much free time on your hands .

3) In hindsight I can certainly see why you might think I was quick to jump on Joe, but you're not aware of the other messages that preceeded my exchange with him that convinced me he was playing the alpha-geek game. As there are few things in life I dislike more than getting pulled into an alpha-geek game, I quickly made it undesirable for Joe to continue so that I could get back to more enjoyable endeavors. One of the best methods to quickly stop such activity is to shine a light on it and call it what it is: bad behavior. Though my timing was off, this is exactly what I did, and it worked. Unfortunatly, because I was too quick to fix the problem, it made me look like I'm nuts, which may or not be true .

4) I think I have a few good reasons for choosing to use the RC PWM outputs rather than the CMUcam2 outputs. I've noticed quite a few questions about the subject this year, so I think I'll give the quick answer here and then follow-up with a more detailed answer in the FAQ if time allows.

Firstly, I wanted teams to have all the source code in their hands so that they could have something to improve upon should they desire, including the searching/tracking code.

Secondly, it made more sense to me to have the camera send t-packets as fast as it could (~11 Hz) by using the Track Color command. Otherwise I would need to used polled mode, which is much less efficient and possibly risky because I'd need to asynchronously cross clock domains twice, instead of once.

Third, I had a hard time getting the camera to initialize correctly. It would lock-up and stop communicating if I didn't send it commands with perfect timing and in just the right order. The experience dealing with the fragile communication interface made me a little apprehensive about using polled mode, and made the use of the streaming Track Color command that more attractive. The last thing I wanted was to be mentioned in the same sentence as the FRC scoring software, so I took the more conservative approach.

-Kevin
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Kevin Watson
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Last edited by Kevin Watson : 30-01-2007 at 23:01. Reason: Questionable grammer.