Hi

Hoping someone will have an answer for me. Vex controller (pic). stopped working. I am unable to reload the master firmware I have tried using RobotC(2.01) and get error 'Failed to enter "Master CPU" Downloading mode'. I've also tried using the IFI loader and get 'Unknown device id [0]' error.

Batteries are full, cable is good (tested with another controller).

The microcontroller will accept a program and regular firmware some of the time, but the program will not run.

Any help is much appreciated, thanks in advance.

David Clark

Hi David -

Sorry to hear about your controller issues. At this point, you've tried most of the recommended troubleshooting steps, but I do have two suggestions:
- Try hooking your robot up to a fully charged 9.6V Transmitter battery while you download the firmware. This will not damage the controller, just provide a little extra power.
- Try your luck with another computer.

Let me know if either of those suggestions helped.

It worked to use a 9.6 volt battery plugged into the controller. Thanks for your help.

Glad to hear it! Keep in mind, though, if your robot consistently needs more power to operate as time goes on, it probably means one of two things:
1. The memory in your microcontroller is slowly going bad, requiring more power to use
2. Your batteries are slowly going bad, providing less power to the microcontroller