Blinkenlights LINked

Things are measured by various network nodes in a networked car so  the instrument cluster no longer has wires to be able to do it directly. The Instrument Auxiliary (IA) node delivers the expected signals and much more to the instrument cluster.

Instrument cluster information is enhanced by employing additional LEDs in the cluster, and by loading extra functions onto existing indicators; such as blinking to indicate a fault with a lamp.

The measured quantities and signals have been identified.

The IA node is also registered with the immobilizer module; with a trust relationship enforced using SHA. When the IA node notices that the car is being driven despite the immobilizer telling other nodes to prevent that; or if the immobilizer module cannot be trusted, the IA node will be creative in how it manipulates the information displayed to the driver through the instrument cluster and the brake warning light.

Window-winding: Electronically and with feeling

A bit of a tangent from a tangent. Best I publish the concept to save all those people from investing in Patents of the bleeding-obvious.

While describing the operation of electric windows, it quickly became obvious that tactile and animated feedback would be not just really nice, but also quite useful. So instead of having just a passive rotary encoder on the control knob, one embeds a stepper motor into the control knob.

Perimeter light guides are illuminated by PCB-mounted LEDs

I confess that that isn’t the simplest way to control electric windows. But perhaps it’s the simplest way to do it nicely.

Electronically-Stimulated Windows

A different way to control electric windows is discussed on a Features page.

This isn’t part of the main project. Especially in view of the cost of electric motors that’d do the job. Incremental cost above that required for ordinary electric window lifters isn’t that big a step. (oh, a pun … you’ll have to read the linked page to understand)

Once again, motivation for presenting this information here is to preserve the freedom of the concepts of the design.

See the green for enhanced stimulation.

Authentically fobbed mobility

I’ve drafted a functional outline of immobilizer operations and secure keyfob interactions.

The system optionally provides for a challenge response system to assure that the holder of the keyfob knows a secret, not just how to wallop the owner over the head.

Keyfob operation is wired or wireless. As it already has the hardware included for both modes, it also provides a secure, wireless connection between the keyfob when plugged into the USB port of a computer and the car’s network allowing diagnostics, configuration and vehicle monitoring from a convenient location.

(I must mention the obvious to protect the freedom to use the idea.)

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.

Decentral Electrics

UPDATED: A diagram added to show current distribution.

One of the motivations for LINbus, both in general and in this case, is low-cost cabling reduction: To reduce the amount and length of cables throughout the vehicle. This has other benefits including simpler, smaller wiring looms that are easier to fit and to make.

And to maintain! I wouldn’t consider it if I didn’t think it’d make life easier.

Production cars however, largely fail to realize the full potential of cabling reduction because they still have centralised electrics, often with a fuse panel in one part of the car for all the lights, motors, heaters, etc. etc. Which of course means that those devices are all wired back to the one location

The MkV Golf has 3 fuse panels with the one at the end of the dash carrying 44 fuses. Keep in mind that each fuse needs 2 wires. One coming from the supply, via e.g. a switch or relay and the other going to the powered device. Are you getting the picture?

Flapping About

LINbus nodes for the flaps; the door and tailgate nodes have now been outlined.

Unravelling the logic embedded in the mirror selection and adjustment switch has been interesting. Knowing that it’s possible to unravel doesn’t make it easier.

This leaves just one node to be sketched out. And to increase the tension, I’m not saying what it is until it’s done!