E- Stop and The New FRC Control System

[Greg McKaskle]

The thing that may cause confusion was the disabling of the user watchdog.

The system has two watchdogs, the system or intrinsic -- controlled by the driver station and DS switches, and the user watchdog -- optional and controlled by the cRIO running the user's code.

If the intrinsic watchdog loses communications or is told to disable or e-stop, the FPGA shuts down I/O. Period.

The user watchdog is ANDed with the intrinsic can request a disable as well. In the movie, the watchdog was simply disabled and wasn't used.

Another usage would be to leave it enabled, and stroke the watchdog in a loop that verified conditions of the robot or joystick. It can be used to ensure that a core loop is executing every cycle and isn't hung or crashed. It can be used to implement a robot enable button on the joystick during early development.

Greg McKaskle