This library supports the Sentinel Robot Controller Board from Footleg Robotics. A motor and servo controller board for the Raspberry Pi computer and Circuit Python on micro controllers. The Sentinel board is designed for building more powerful robots with a safety feature of a hardware watchdog circuit to prevent runaways and unplanned robot carnage should a code problem occur. Using hardware PWM to control the motors and servos allows consistent control without relying on the precise timing of the controlling computer. But this bring with it the problem that if your code stops talking to the hardware then the hardware will continue to execute the last instructions given. If your Raspberry Pi crashes or your code throws an uncaught error your robots could carry on running away from you leaving you without control. To prevent you having to chase your robots over the horizon, the Sentinel board watchdog circuit keeps everything under control. If the the watchdog input does no receive a signal for over 1 second it will automatically shut down all the PWM outputs, stoping all the motors and servos from being driven. If your code is not talking to the robot then the board will shut it down.