https://content.vexrobotics.com/docs/VEX_Robot_Troubleshooting_Flowchart_0811.pdf
This flowchart is very useful for troubleshooting problems, however I have run into a few obscure problems that are not covered in this flowchart. I am going to be going through two of them, and explaining the problem and what I did to fix it.
Both of these problems are related to USB port on the cortex.
Problem #1
The first problem was very odd. While doing some autonomous programming wirelessly, the usb port seemed to suddenly stop functioning. Problems from this include, vex net communication seizing and inabilty to download programs. The error message achieved when attempting to do so was:
“Failed to verify that the serial link is connected to a Robot Controller.
Cannot communicate with VEX Cortex SlaveCPU. Master CPU communication is working.”
Solution: The solution for this was very simple, simply reflashing the firmware did the trick for me.
Problem #2
Before explaining this problem, I would like to preface it with a video.
This is what cortex LEDs, should look like when being turned on under normal circumstances:
Now let me explain the problem. This time the usb port was unable to do anything. No vexnet connection, and when trying to connect the cortex directly to a computer(Windows 10), I was greeted with this lovely message:
“The last USB device you connected to this computer malfunctioned, and Windows does not recognize it”
Not only was I getting this error, but the LEDs on the cortex were also out of wack:
Reflashing the firmware was not possible in this situation as Windows was not able to communicate with the cortex.
Solution: This solution is a bit odd, but bear with me. On the cortex next to the backup battery port there is a hole that says config. Within this hole is a button, I know this is obvious but I am trying to be detailed. Press this button and hold it with something thin, I used a allen key. The cortex will precede to cycle through a bunch of light patterns, but it eventually settles on the correct pattern (all green). After this turn off the cortex, power cycle, and it should be back to normal.
Hopefully this thread will help someone; feel free to add you own tips/solutions, and please point out if I have done something wrong or taken the hardest route.