Overview
The objective for the driver controls firmware is to create a robust system capable of both properly keeping track of the state of the vehicle when responding to user inputs, as well as being able to send out the correct messages to other subsystems of the car.
The driver controls system works by waiting for the user to take an action such as a button press, which will then be used to construct an event to push to a global queue. When the event is ready to be raised from this queue, the system observes the current state of the car to determine whether the event is safe to be processed at the current time. If an event is raised at an unsafe time (i.e. flooring it while in neutral), then the event will be discarded.
To monitor the current state of the car, a series of Finite State Machines is used to monitor each input device. The different states of each FSM have a corresponding check function, which can be used to approve or decline an event according to it's current state. Essentially, if an event is raised and the states of every FSM are aligned in such a way that all their check functions return true, then the event can be considered safe to run at the current time.
Sequence Diagram
