Interference from channels

In my school, a group of us started building a robot for the Round Up. We have two motors, controling wheels on the left and right side of the robot, hooked up to channels 2 and 3, and two seprate motors hooked up to 5 and 6. We noticed that when we used the two other motors, those atatched to 5 and 6, primarily 6, I believe, the 2 and 3 motors jerked around a bit, but not the other way around. It is not a matter of outside interference, as we swapped out different sets of control crystals, to the same effect. Does anyone know what may be causing it, and whether or not this problem is fixable?

First of all, I would look into switching to VEXnet. Otherwise you’ll just have to check your code and see if you can troubleshoot from there.


often times when the batteries are attached and you are not driving or anythings the motors will “mysteriously run.” this cannot really be avoided as far as i know but it is not unusually to see with both crystals and vexnet.

This problem can sometimes be solved on the crystal transmitter by recalibrating/re-zeroing. On the transmitter, on the 2 circles surrounding Channels 3/4, and 1/2, there are 4 small oval flat buttons. If you have a motor connected to Channel 2 and it runs when Channel 2 is in the “stand still” position, press the small flat button labeled “Channel 2” and it should cause the motor to speed up or slow down. Keep pressing the button until it stops where you want it.

A side effect may be that by resetting your “zero”, it might decrease the sensitivity to interference from Channels 5 and 6, solving your first problem as well.

on vexnet yesterday during a competition we had one of our teams using only a 2 motor arcade block in the code the drive motors were moving at full speed with no buttons or joysticks being used. any ideas to why that happened?

  1. Bad driving software
  2. 3-wire motor PWM cables plugged in backwards

Offhand, I can’t think of anything else that would cause that.

the team was running the newest version of Easy C V4. The only thing in the code was a 2 motor arcade block. we rewrote this simple code a few times with the same results. we tried other motors and it did the same thing. even with new firmware the results were duplicated. eventually it was resolved, but we are not sure what exactly happened or how to prevent it in the future. thanks for the help!