Oh what a tangled mess we weave

I scribbled a post on the evils of persisting central electrics earlier today. While composing that article, I updated the information of the tailgate node to illustrate how it could reduce the peak current load, allowing the use of smaller and more flexible wires.

Similar measures can be implemented in e.g. the doors by stopping the mirrors from moving and being heated while the lock actuator is working.

As the voltage drop through a wire is related to the total current draw, reducing the load temporarily lets something else happen for a fraction of a second to three, providing a higher operating voltage for that action.

After adding a diagram, I promoted today’s earlier post to a page so that it doesn’t slip away with the blog post history.

The LIN Node Design page now has a diagram showing the locations of nodes and their clusters.

Building the Matrix

First steps in establishing the network object matrix of the vehicle network. This is about half-way through the detailed draft design of the network. Door, tailgate and rear-body and instrument proxy nodes are still to be defined.

Every node “owns” the devices that it connects to the vehicle network, along with the associated device states and the node’s internal management parameters.

This provides a rich set of status and diagnostic information that can be selectively used by other nodes in the vehicle network. All the exported information can be queried when trouble-shooting.