[Help] OI Modification

[roboticsguy1988]

now would replacing the green LEDs with blue ones be against the rules. My guesss is so.

Also on average what does a blue LED draw? Basically how many Blue LEDs could you use before you reach 10ma?

[BrianBSL]

Originally Posted by roboticsguy1988

now would replacing the green LEDs with blue ones be against the rules. My guesss is so.

Also on average what does a blue LED draw? Basically how many Blue LEDs could you use before you reach 10ma?

You decide how much current to give them, based on the resistor size you use in series with it. But at 10mA, you are not going to get more than 1 LED unless you use a larger resistor and thus have the LED be less bright. Some "bright" LED's produce their rated intensity at a forward current of 20mA or more, sometimes even in the hundreds of mA for very bright LED's (although this is extremely rare).

[Tristan Lall]

Originally Posted by EricH

Having a portable computing device (laptop, PDA, etc) on the robot--the inspectors will call you on it pretty quickly, and so will the refs if the inspectors miss it.

Actually, in principle, it's not illegal. It is an additional electronic component, and subject to those rules.

[MikeDubreuil]

Originally Posted by Tristan Lall

Actually, in principle, it's not illegal. It is an additional electronic component, and subject to those rules.

Actually, I think you could put a very fast computer together that would fall within the rules. There's really only two limiting rules. The $200 per component limit and the $3500 budget. You could follow those rules and still add a top of the line computer to your robot.

Athlon 64 3500, $200
Mortherboard, ~$150
memory, ~ $100
HDD, ~$100
Linux, $0

You could have a very powerful computer on your robot.

[Al Skierkiewicz]

Originally Posted by BrianBSL

You decide how much current to give them, based on the resistor size you use in series with it. But at 10mA, you are not going to get more than 1 LED unless you use a larger resistor and thus have the LED be less bright. Some "bright" LED's produce their rated intensity at a forward current of 20mA or more, sometimes even in the hundreds of mA for very bright LED's (although this is extremely rare).

I think it is important to make an explanation here for casual observers. The LED outputs are switched to the 5 volt power supply through an internal resistor. This resistor will correctly limit the output current to 10 ma when connected directly to an LED (without a resistor).
From the OI Reference Guide, p.5, "The LED drivers provide 5V that is current limited to 10mA. Connect the LED’s anode to the desired LED drive pin. Connect the LED’s cathode to any ground pins."

[zachriggle]

So is the 10mA limit just on the OI, or is there a 10mA limit on LED's on the Robot itself?

[Eldarion]

Originally Posted by zachriggle

So is the 10mA limit just on the OI, or is there a 10mA limit on LED's on the Robot itself?

It is a hardware limitation on the OI's LED output pins.

[BrianBSL]

Originally Posted by Al Skierkiewicz

I think it is important to make an explanation here for casual observers. The LED outputs are switched to the 5 volt power supply through an internal resistor. This resistor will correctly limit the output current to 10 ma when connected directly to an LED (without a resistor).
From the OI Reference Guide, p.5, "The LED drivers provide 5V that is current limited to 10mA. Connect the LED’s anode to the desired LED drive pin. Connect the LED’s cathode to any ground pins."

Thanks for that catch. I had read that a few days ago, but didn't think about it this morning when I posted the original reply.

[Andy A.]

Originally Posted by zachriggle

So is the 10mA limit just on the OI, or is there a 10mA limit on LED's on the Robot itself?

You could deck your robot out in enough LED's to light up the arena, assuming the refs don't decide it's annoying/distracting. What that would gain you, I don't know. LED feedback on the robot would be pretty difficult to justify, since it's extra weight you already know you don't have to spare and It's difficult enough to see. Recall that the robot can be 50 feet away separated by thick plastic and surrounded by 5 other robots. Your going to have a real hard time seeing a couple of LED's on your bot.

If you really want to have some LED feed back, have one connected to your OI through one of the joystick ports. It's not to difficult to have any one of the 8 eyes on your drive team look down to see if you have that lock on. I know that Blue LED's are all the rage, but green and red are a whole heck of a lot cheaper and just as visible.

My team has kicked around the idea of putting a 'ball' on the OI. Basically its a cross of 5 LEDs. When the camera sees the target, it returns a value of how far and in which direction the light is from the center of its field of view. If it is to the left, the left most light would light up. if it is to the right and up, the top and right LED's light and so on. When it is dead on, or close enough for a good shot, the center lights up. It has the advantage of letting you know not only if you are on target or not, but how to get on target. While the RC could correct for this automagically, it's nice to put some control in the humans hand. It's an idea somewhat borrowed from the aviation world, in which the 'ball' is a grid of lights that a pilot can see at the end of the runway (or carrier deck) and informs him of where he is in relation to the glide slope.

-Andy A.

[Al Skierkiewicz]

Originally Posted by zachriggle

So is the 10mA limit just on the OI, or is there a 10mA limit on LED's on the Robot itself?

Zach,
There is no LED output as on the RC. The LED outputs on the OI are for indicators you can map and add to your operator interface. Lighting on the robot itself comes under the heading "decoration" and can be powered from the main battery. Be sure to follow the rules here though in relation to decorations, electrical and interference.