Answered: USB to USB Connection Problems

After downloading the latest version of RobotC along with all its firmwares, we ran into some communication problems. I like to drive with a USB-USB cable so that it conserves batteries. When I hit the wall and lose communication or when the USB-USB gets unplugged on one end or the other by the driving robot, I lose future communication altogether.

When I try to USB-USB the controller and the brain together again, the "Robot" light on the joystick will blink green, and then all the lights on the joystick will blink red; it follows that pattern over and over again.  On the brain, the "Robot" and "Vexnet" lights blink green, and then all the lights blink red.  This pattern too, occurs over and over again.  The only way I could get communications is when I downloaded all three firmwares again.  This seems unnecessary and improper, since it isn't feasible to redownload firmware every time we lost communications.  I don't get this problem when driving wireless since I don't abruptly lose communications like I do when using the USB-USB.  I also never had problems like this until today, when I downloaded the new version of ROBOTC.  Would this be a problem with our Vexnet or just RobotC?

Our system is not hot swappable, so have you tried to just do full power cycle and see if it would recover without having to reload firmware or code!

Yes. I’ve tried cycling power and it didn’t really effect it, but after re-downloading firmware the next day, it seemed to work fine. The problem seems to come and go; luckily it disappeared by the time Championships came around.