Led Tape Control

[WizenedEE]

(I'm on Celestial's team)

Originally Posted by DonRotolo

...but this is a DIFFERENT PWM than what is used to control Jaguars and servos. The PWM outputs of the Sidecar won't work for you.

So the jaguar outputs are similar to standard servo outputs and don't just turn on and off depending on how fast the motor should turn? I guess that makes sense, because the jaguar has those special abilities rather than just being an h-bridge.

Originally Posted by DonRotolo

In this case, you just want to display 3 colors (Red, White, Blue). Why not run to Radio Shack and buy an LED in each color and just connect those? Lighter, cheaper, simpler to implement. Just be sure to use a dropping resistor to bring the 12 volts down into the LEDs range - the package or an Internet resource should help you there.

We might just go with that, but we're under the weight limit. I was also thinking of having some sort of victory dance with them.

Originally Posted by 3p1c w1n

How does that work? I thought you could only attach one device, like a compressor, and it's either on or off.

Well, the LEDs are hard-wired to +12V and just need to be controlled by grounding them. If we attached one lead to the green and one lead to the blue, we could get blue by running the "motor" one way, which would provide +12V to one side (making nothing happen for lack of voltage differential) and GND to the other side (making the blue light up). However, the spike probably wouldn't let us make each side GND (it would just disconnect them if we turned it off) or 12V (why would it?)

Originally Posted by Foster

For Lunacy we had a LED light strip to signify that a ball was ready to shoot. They came from a car supply place and were controlled by a Spike. We used blue, but they come in red, blue and white, about 12 LED's in a 24" strip. Can you post the link to your tri-color strips?

http://www.adafruit.com/index.php?ma...ducts _id=285

Originally Posted by Foster

You could even go wild and have it be solid on for the low, slow flash for the med and fast flash for the high so your robot partners know where you going.

Haha great idea!

What wiring up MOSFETs instead of spikes? It's a custom circuit anyway, and MOSFETs weigh aabbbooouuttt 1% of what a spike weighs and 6% of what it costs, and is much easier to control.

[apalrd]

Originally Posted by WizenedEE

However, the spike probably wouldn't let us make each side GND (it would just disconnect them if we turned it off) or 12V (why would it?).

Yes it will. In LabVIEW, the Relay Set is an enumerated type with 4 states: On (both sides 12v), Off (both sides gnd), Forward (one side 12v, one side side gnd), and Reverse (other side 12v, and other side gnd).

The spike is really two relays, and the three-pin cable contains two digital lines (fwd and rev) plus ground. The first coil (fwd) switches m+ between GND and 12v, and the second coil (rev) switches m- between GND and 12v. The output is never disconnected. Hope that makes sense

[Foster]

Thanks for the link to the Adafruit site, those LED's look great.

Output devices like motors, compressors, etc need to be controlled by Victors or Spike like devices. You could always ask the GDC for approval to build a custom circuit to drive the LED's. Since it's part of your game play, you can't use the decoration rule. You could see if the Victors will drive them to the bright/dim that you want and see if the GDC will let you put a non motor on the device.

We went with the Spikes to make sure there were no inspection issues.

Good luck!

[WizenedEE]

Originally Posted by Foster

Output devices like motors, compressors, etc need to be controlled by Victors or Spike like devices. You could always ask the GDC for approval to build a custom circuit to drive the LED's. Since it's part of your game play, you can't use the decoration rule. You could see if the Victors will drive them to the bright/dim that you want and see if the GDC will let you put a non motor on the device.

I assume you're looking at <R03>? That's a weird rule -

Originally Posted by 2011 Game Manual

<R03> Custom circuits and COTS electronics are expressly prohibited if they:
A. Interfere with the operation of other ROBOTS.
B. Directly affect any output devices on the ROBOT.

Wouldn't Jaguars and Spikes be COTS electronics? Although it does say you can use anything in the KOP, so that rule would take preference? I'll probably ask the GDC if lights are considered output devices.

Victors are another good idea, but we can just make our own PWM in the robot code for the spikes.

[3p1c w1n]

I think I will just stick to LED's of one color per spike for simplicity. Really noob question, but what vi would I use for a spike? The only thing I've used a spike for is the compressor, which has it's own set of vi.

[3p1c w1n]

under utilities I found "FRC LEDs.vi". It allows a choice of 2 LED types, FPGA LED and User LED. The state is either on, off, or toggle. Is this anything close to what I want?

[Joe Ross]

Originally Posted by 3p1c w1n

under utilities I found "FRC LEDs.vi". It allows a choice of 2 LED types, FPGA LED and User LED. The state is either on, off, or toggle. Is this anything close to what I want?

Those change two little tiny LEDs that are on the cRIO. They are probably not what you want.

[Steve Warner]

While the Spike has 4 output states, last year the WPILib C++ Relay class only allowed 3 states. The state where both outputs were switched to +12v was not allowed. I guess they did not consider it useful. In the off-season we tried including the Relay class code in our project and modifying it to allow the 4 states and it worked. I have not seen the source code for 2011 (is it available?) but I am hoping they changed it to allow all 4 states. I don't know how LabView or Java work.

[Foster]

I would propose that you ask the GDC if custom electronics can be used to run the lights.

If you get turned down then I would ask if a Spike controls the power to the custom circuit that drives the LED would be acceptable. The GDC is super safety minded and that is one of the reasons for the output via a Spike, Victor or Jaguar. The cRio safety code controls the output to them.

As far as the Spike vi goes, the one for the compressor is good. It wants the robot to be enabled and then uses the value from the pressure sensor to turn the spike on and off. You would feed inputs into the vi as if you were the pressure sensor.

Remember, it's always faster to ask the GDC rather than fooling around in a CD thread collecting opinions on what the GDC will say.

[3p1c w1n]

Originally Posted by Foster

As far as the Spike vi goes, the one for the compressor is good. It wants the robot to be enabled and then uses the value from the pressure sensor to turn the spike on and off. You would feed inputs into the vi as if you were the pressure sensor.

Thanks! I didn't think about feeding inputs to it.

[apalrd]

There is a VI to set a relay. It is much better than trying to use the Compressor VI to set the relay. The compressor VI (in LabVIEW) creates a new thread, constantly getting the pressure switch and writing the relay. Under the WPI Robotics Library palette, go to Actuators->Relay and use the Relay Open and Relay Set VI's.

[Al Skierkiewicz]

The Spike relay is not rated for rapid ON/OFF operation if you are intending to make flashy lights. If the LED device you are using requires a simple ON/OFF power connection, and it draws less that 20 amps, the Spike is a perfect fit.