Robot randomly moving motors (running PROS)

We’ve suddenly run into an issue in our last competition where, at random times, we would lose control of the robot (it would stop listening to the joystick), and our two drive motors, plugged into ports 1 and 10, would start slowly moving. All other motors that were being run at the time of the glitch starting would continue to run. Shutting the joystick off wouldn’t stop the robot, leading me to believe that this was not a code issue. The VEXnet LEDs on both the robot and the joystick would rapidly flash green, and the Robot LED on both would slowly blink red. This happened over multiple batteries, but never happened if the drive motors were unplugged. Eventually, the problem simply disappeared. We are running PROS, and I have a hunch that that has something to do with the issue.

Here is a video of the issue happening:

I know this isn’t a lot of information, but does anyone know what the problem may be?

Slow blinking red Robot LED means processor fault IIRC. Are you running IMEs? Sorry I didn’t watch the video as I’m on my phone on data. The static issues with those can cause the cortex to crash and behave like you described. We had that happen several times a couple years ago.

Hi @kingsting,

The slow-flashing red LED on the robot light indicates that the user microprocessor has had some sort of fault. Most commonly, this occurs as a result of IME static. From the video, however, it didn’t look like you had the I2C bus in use. Can you post, PM me your code, or email your code to

Thanks for the help! I don’t have access to the code right now, but I will tomorrow. We aren’t using IMEs, but we are using Optical Shaft Encoders.

I was about to post this issue this morning, as I haven’t seen this happen to anyone else but ourselves. I believe we are having the exact same issue. It doesn’t happen as frequently now, but at times the robot will loop the last transmitted signal from the joystick, and like you said turning off the joystick wouldn’t solve anything. This was especially irritating when it happened early in matches, and we couldn’t do anything for the remainder of the time. We are using multiple quad encoders on the robot now, but at the time we had just one on the flywheel. I’ve seen people have issues with IMEs, yet haven’t seen one just like ours with a quad encoder. We’re currently using easyC simply because we had a copy, but we’ll be transitioning to RobotC soon. If you’re using easyC that might be partially at fault for both of our issues, who knows.

We have also had this issue. It seems to be normal in practice (usually if we bump up against the wall or once when we tried to climb our FTC RES-Q mountain) but it’s only happened once during a match which leads me to believe environment can have something to do with it, like maybe 2.4ghz router. Fortunately we just got a 5ghz router so maybe it will be less frequent.