Dead Brain Ports, G18, and G3

Interesting. Any idea what would cause the behavior in the video in the OP then?


hard to tell without testing the motor on another system, but my first guess would be damaged H bridge inside the motor.


The specific instance started at 5:18:04. Ended up unplugging the battery. I talked to the team after the match and they said the motor was fine, but the brain port was dead.


Wouldn’t coast mode make more sense than the brake mode?

True. Also controller or radio firmware may have malfunctioned, preventing field control commands to get delivered to the V5 brain.


If the motor is turned when disconnected from the brain, it’s possible for enough voltage to be generated to cause the cpu to boot, we put the motor into brake to try and stop the motor being turned any more.


It looks like they lost all control 20 seconds or so before the end of the match.
usually if radio comms is lost, motors will be stopped. but I guess it’s possible that part of the controller crashed and left the radio still communicating with the field enabled status.


Every time we’ve lost a port or motor it continuously spun in the direction it was initially moving in. I’ve never had an instance where a port died and the motor stopped. This is even after we disconnected the controller.


unfortunately not something we can easily simulate, perhaps whatever takes out the port also causes issues inside the motor. We do our best to make the system as robust as we can given the constraints we have to work with.


I love it when mentors reply with passive aggressive smiling emojis it is so professional and kind and awesome and appreciated and makes my day every time.


Coming late to the game … I did walk back gut reaction, that will teach me to multitask.

The smiling is not passive aggressive, but in part to recollections of Head Referee having to deal with our teams battery due to a short at Worlds 2014. He carefully removed the smoldering battery by the leads and walked it over and asked “do you want this back?”

Sometimes a smile is just a smile.


I just want to come back to this thread and note that today during practice we did have a port on the motor die, and the motor did continue to spin with a solid light even with user code stopped as shown in the video in the OP of this thread. Power cycling everything yielded a slow blinking light on the motor (and no movement, so seems like h bridge is intact). So it does seem like it is possible for a damaged port on the motor to cause a motor to continue spinning after a match is disabled.