Too many PWM's shorting out power?

[Hawiian Cadder]

Could you specify the solution you found? We have a Crio that will only do 2 motors controlled at the same time and are utterly stumped.

[Landonh12]

Originally Posted by Hawiian Cadder

Could you specify the solution you found? We have a Crio that will only do 2 motors controlled at the same time and are utterly stumped.

Our cRIO was plugged into the power supply for a camera, so it wasn't getting enough power.
What are you programming in?

[el_pablo]

We are having the same problem.

When we try to control more than 2 motors with the PWMs, the system starts to have problem.

Scenario 1
With the Axis camera, when running the 2 step motor, one of them starts to skip. Adding a third motor, both of step motors jitters.

Scenario 2
Using 2 jags and 1 victor, one jag skips every few seconds.

So what could be the problem? Power?

Thanks for helping

[Alan Anderson]

Originally Posted by el_pablo

We are having the same problem...
So what could be the problem? Power?

The same symptoms suggest the same fix: make sure you are properly supplying 12 volts to the Digital Sidecar from a 20 amp breaker on the Power Distribution Board.

[slijin]

Originally Posted by el_pablo

Scenario 1
With the Axis camera, when running the 2 step motor, one of them starts to skip. Adding a third motor, both of step motors jitters.

To add to Alan's response, check to make sure that the frame of the Axis camera is isolated from the robot's, as the Axis camera is grounded to its frame.

[el_pablo]

Here is a video I made yesterday during the testing.

It's in french but I wrote in a previous post what is happening.


Youtube video here

As you can see, it jitters even when not running.

Here is a screen shot of our begin.vi


Here is the teleop code


Thanks for helping

[Alan Anderson]

el_pablo:

When you said "step motor" before, did you mean "servo"?

You're defining the camX and camY servos, but you never command them to move.

The nouveauMotor device reference is not defined in Begin. You should be seeing an error message on the Driver Station telling you about that.

I can't see YouTube videos from where I am, but I'm going to guess that you haven't installed the servo power jumpers next to the PWM pins on the Digital Sidecar for the camera servos. If they are indeed being powered, then a "twitch" is usually an indication that they're not getting a PWM signal, and are just picking up noise on the wires.

[el_pablo]

Sorry my mistake, they are servos not stepmotors.

The diagrams show the second scenario which includes 2 jags + 1 victor and no servo. Althought they are declared we don't use them in this test case.

Concerning the servos, the power jumpers are installed.

We started the project using the default template. Should I delete a few things before coding?

Thank you

[el_pablo]

Just figured out that in the begin.vi there were some "junk" declaration out of the screen in which some PWMs were in conflict...

I hope this is source of the problem.