I want to replace my original head unit with an upgraded Android unit. The question that has arisen in the purchasing process is the CAN Bus in a Gen. 2 Prius analog or digital? I was unaware that there were two different means of communicating over the CAN Bus. If you could assist me with an answer to this question I would appreciate it very much.
I'm still unaware of that. Though it's a truism that every digital transmission link is all analog wizardry if you look closely enough.
There are devices around for capturing analog data and converting it into CAN bus frames. Otherwise, it is a digital system, logically. That said, it works by comparing the voltage on two wires, both of which go up and down. As opposed to a single wire which goes up and down and is compared to a fixed ground. See the article on Wikipedia: CAN bus - Wikipedia and this illustration is particularly helpful, with Can H and Can L being the two data wires which are compared:
Thanks for the rapid response! The details for the Android head unit I am considering has this statement. "Steering Wheel Controls: Control your double din android car stereo while keeping your hands on the steering wheel. * The unit supports analog SWC signal. If your car is controlled by digital signal, then a SWC adapter cable(not included) is needed to transfer the digital signal to analog signal." How should I respond?
That's probably not talking about a CAN bus at all. A gen 2 uses multiple network technologies: AVC-LAN, BEAN, and CAN, as you see in this manual excerpt. And then there are things that aren't network connections at all. The steering wheel buttons are nothing but an arrangement of pushbuttons and resistors that pull two analog lines down toward ground by different amounts: Nothing there but wires straight from the buttons to the radio/player. I would call those analog steering wheel controls. Nothing to do with CAN or any other network though. In gen 3 there were two ways it could work. Some gen 3s have what Toyota calls a "touch tracer" display, where pictures of the steering wheel buttons show up in the instrument cluster to show what you're about to push, so you can be sure without looking down. They do it using the same number of wires from the steering wheel (even though it needs all the original signals plus the "where is my finger" signal). They did that by building a little microcontroller into the steering wheel, and redesignating two of the "button" wires to be power and ground for the microcontroller, and redesignated another to carry a digital signal saying what button is being touched or pushed. And they're still just private wires between the wheel and radio/player, not any kind of network. And in the models without "touch tracer", just the old familiar analog connections are used. But I don't think any of that microcontroller wheel-button magic was used in any gen 2 (in the US anyway).
