It is the Chief Electronics task to keep an overview of all the electrical systems in the car. The amount of lines in each individual PCB is already a complex map where you quickly get lost in the corners and holes the routing has. All these lines and components on the PCB have a function and that function has to be communicated with the rest op the car. Making just one PCB for the whole control system of the car sounds like a lot of complicated work, and it is precisely that! That is why we divide the system up in smaller more manageable parts.
At the start of the year we listed all the inputs and outputs the system should have, interfacing with the other departments in the team that all have their wishes as well for sensor inputs and devices that have to be powered. You use all your inputs to control the outputs, that is the idea of the control system, but how are you going to do that?
We divided the car up in sections that are more manageable and easier to design. Less tasks per PCB does mean more PCB’s. All of these PCB’s need to know of the wishes and functions of the other PCB’s it interacts with. Now the trick to keep this organized is to make a clear top-level overview of the whole car, in which you connect all the different devices. One wire at the time you connect all the outputs to the point where is will be an input. At the same time try to design the top-level in the same rough shape as the car.
This way you can easily check if every device has the correct connections and that every PCB gets the info it expects and their outputs are actually used somewhere in the car. Another benefit is the actual layout of the car is on a sheet now, this is a road map of all the connections in your car. Every wire has a start and end, voltage and power rating. From this map you can derive how many wires will have to be routed through the car. The main loom will consist of almost 40 wires and knowing exactly which ones will help you not forget one in the end. Forgetting one cable in your car can mean the difference between going 130 Km/h or standing still. Where is your car going if the accelerator pedal is not connected, not that far.