Underglow LED Control using WPI_DigitalOutputGeneratePWM.vi

[Dfontana]

Originally Posted by Joe Ross

PWMSetValue will output a servo style PWM signal, which is not what you want for your LEDs. WPI_DigitalOutputGeneratePWM.vi is new this year, and you might not find anyone who's used it before. Don't be afraid to experiment.

Is there a significant difference between the two?

[Joe Ross]

Originally Posted by Dfontana

Is there a significant difference between the two?

servo style PWM gives you a pulse width between 0.67 and 2.33 ms, repeated every 5, 10, or 20ms. You have a very limited range of duty cycles and frequencies. It's suitable for driving a servo or a speed controller, but not much else.

The digital output PWM lets you set a duty cycle between 0-100% and a frequency from 0.6hz to 19khz.

[porterma64]

One thought for use of robot underglow is driver/alliance feed back. The driver will more than likely use this to tell if a lifter is in position. Maybe different colors desginate different lifter levels or signaling to the feeder stations what tube(s) to dispense. There are a lot of good ideas with this. Our team has been entertaining these ideas, but has not been high on the priority list. I hope to see if we can get it to work and let you know.

Mike Porter
FRC 815 Advance Power

[Matt Krass]

Originally Posted by Joe Ross

servo style PWM gives you a pulse width between 1.67 and 2.33 ms, repeated every 5-20ms. You have a very limited range of duty cycles and frequencies. It's suitable for driving a servo or a speed controller, but not much else.

The digital output PWM lets you set a duty cycle between 0-100% and a frequency from 0.6hz to 19khz.

Wouldn't that be 0.67 ms and 2.33 ms? Or am I just getting sleepy?

[WizenedEE]

Originally Posted by Matt Krass

Wouldn't that be 0.67 ms and 2.33 ms? Or am I just getting sleepy?

Wikipedia says standard servos go from about 1.25 to 1.75ms, so it makes sense the digital sidecar can do more than that (duh )

To the OP, what are you using to control the LEDs? FETs? Spikes? Victors?

[RyanN]

Originally Posted by WizenedEE

Wikipedia says standard servos go from about 1.25 to 1.75ms, so it makes sense the digital sidecar can do more than that (duh )

To the OP, what are you using to control the LEDs? FETs? Spikes? Victors?

Two 2N2222 in the T092 package per channel. Ours are rated for 800mA each, so we have 1.6A of capability. I put in two to handle heat dissipation a little better. The weakest link in our box is the 12V regulator, rated for only 1A.

I'm not 100% sure of the current of each bar for each channel. We may have to bump it up to 2 or 3 voltage regulators, or we could drop the voltage regulator completely because of the fact that the RGB bar is pretty rugged.

[arizonafoxx]

I am wondering why you want to use PWM. Are you trying to get a color in between RGB YCM W? If you are just looking for the 7 basic colors couldn't you just use digital IO Out to drive the base of your transistors and then have power and ground come from the PD board? If I am thinking correctly this would be legal and fused at 20A.

P.S. Our team bought one of these flex strips as well. I like the fact that you can cut the bars in sections and just add wires to increase number of strips you have.

[Greg McKaskle]

Silly me. I thought these were for illuminating the retroreflective strips on the columns and grids.

Greg McKaskle

[RyanN]

Originally Posted by arizonafoxx

I am wondering why you want to use PWM. Are you trying to get a color in between RGB YCM W? If you are just looking for the 7 basic colors couldn't you just use digital IO Out to drive the base of your transistors and then have power and ground come from the PD board? If I am thinking correctly this would be legal and fused at 20A.

P.S. Our team bought one of these flex strips as well. I like the fact that you can cut the bars in sections and just add wires to increase number of strips you have.

We wanted to control the color in the RGB spectrum.

This might give you an idea.

LED Control.vi

By the way, we never got to testing it today. We got busy doing other stuff, and this is very low priority.

[Joe Ross]

Originally Posted by Matt Krass

Wouldn't that be 0.67 ms and 2.33 ms? Or am I just getting sleepy?

You are correct, I edited my post.