[Help] OI Modification
 

What is the legality of opening up the OI and, say, replacing some of the LED's with piezoelectric speakers? I'm thinking a lock-on tone (when the camera has a lock on the target at 5ft., and has aligned the launching mechanism accordingly) would be a lot better than a lock-on LED. Taking your eyes off the robot to keep checking for a lock = bad.

Re: [Help] OI Modification
 

Not even remotely legal. Remember though that the OI has LED outputs available on some of the joystick ports - but you can only draw 10ma of current from them.

Another consideration is that the competition venues are extremely noisy and it might be very difficult to hear a buzzer or sound.

Re: [Help] OI Modification
 

definatly illeagal, but also if you screw up and break your OI you void your warrenty...

Re: [Help] OI Modification
 

The definitely legal way to do this: attach a portable computing device (see <R74>, <R77>, and <R78> for applicable rules) and rig it to give the sound. This is assuming you can hear the noise in an arena with loud music and cheering, of course. I'm not sure that modifying the OI in this way is legal, even if it were a good idea (which it isn't).

Re: [Help] OI Modification
 

See the OI documentation available here. The LEDs are "echoed" on the PWM connectors. If you can find a beeper that works at 10 milliamps, and that you can hear over the noise at competition, go for it.

If the issue is just not wanting to look away from the field to see the indicator, you might consider a "head-up display", with one or two LEDs mounted to the corner of your operator's safety glasses and wired to a connector on your OI.

Re: [Help] OI Modification
 

See the second sentence in Rule <R61>.

It has been said before, but it is worth saying again: please read ALL the rules for the game! In particular, read sections 3,4,5 and 6 carefully. The manual is chock-full of really useful information.

The 2006 FRC Manual: Read it. Learn it. Know it.

Re: [Help] OI Modification
 

If you're looking to do a lock-on indicator, a visual cue is much more effective field-side. Back, in 2003, 67 used a hat-mounted LED to tell the stacker operator when the stack was secured by the stack-hold-down mechanism. So, in any case it is possible, and in fact, we're probably going to do the same target-lock idea you're aiming to do this year as well.

Re: [Help] OI Modification
 

Ooh, I like that idea a LOT more, actually. We'd need a hella bright LED array, though. Anyone know where to get a bunch cheap blue LED's (don't say Radioshack, because I said *cheap* LED's)?

Speaking of LED's... is it legal to interfere with other teams' guidance systems (i.e. spewing lots of IR all over the field in order to mess with proximity sensors). I know it's not legal to cause physical damage, but the rulebook said nothing on this sort of defense.

Re: [Help] OI Modification
 

How many portable computing devices are we allowed to bring? (I was thinking along the lines of a laptop for software reprogramming/modification, and my PDA to link to one of the serial ports to display performance data, etc.).

Re: [Help] OI Modification
 

You may bring as many computers as you want to the competition, for use in the pits. However, that doesn't mean you will be allowed to use them on the field.

Re: [Help] OI Modification
 

The LED outputs on the OI are current-limited to 10 milliamps. This basically means you can connect only one LED to each output.
You really should read through the whole manual... this question is also addressed directly:

Re: [Help] OI Modification
 

Is that in the Game section or Robot section (dont have a rulebook handy on me at the moment).

@Edit
Also, the "hella bright LED array" would not be on the OI, but rather on the robot itself (as had been suggested for a visual-cue for a lock-on, as opposed to a (however cool) lock-on tone).

Is there a milliamp limit on LED`s on the robot itself?

Re: [Help] OI Modification
 

You won't find any rules for this but Gracious Professionalism keeps you from even thinking about it.

Re: [Help] OI Modification
 

It's also illegal to use this "defensive" method.

<R31> No devices or decorations are permitted on the robot that are intended to jam or interfere with the operation of the vision system (i.e. changing robot color to confuse opponent’s vision system).

FLOWCHART: (Page 14, Section 5) Question 1: "Is the part a safety hazard or likely to damage robots, the field, or interfere with the humans or the controls?" ---> "YES" ---> "No! It may not be used!"

Also ...

It was mentioned above that you can bring as many laptops and PDAs as you'd like, but as for using them on the field, that's a no-no.

<R59> Custom Circuits may not:
• Interfere with the operation of other robots
• Directly alter the power pathways between the battery, fuse blocks, speed controller/relay, and motor. Custom high impedance voltage monitoring or low impedance current monitoring circuitry connected to the robot’s electrical system is acceptable, because the effect on the robot outputs should be
inconsequential.
• Directly affect any output devices on the robot, such as by providing power directly to a motor, supplying a PWM signal to a speed controller or supplying a control signal to a relay module
• Be used for wireless communication, such as sending or receiving a signal to and/or from the alliance station
• Connect to the radio or tether ports on the Robot Controller

Re: [Help] OI Modification
 

Yes--and no. You are allowed to hook them up to the OI, as per the rules in my previous post in this thread. You can have the RC tell the OI to make x device make y noise. That's legal. 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.

Re: [Help] OI Modification
 

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?

Re: [Help] OI Modification
 

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).

Re: [Help] OI Modification
 

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

Re: [Help] OI Modification
 

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.

Re: [Help] OI Modification
 

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."

Re: [Help] OI Modification
 

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

Re: [Help] OI Modification
 

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

Re: [Help] OI Modification
 

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.

Re: [Help] OI Modification
 

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.

Re: [Help] OI Modification
 

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.