The light panel portion of my Knight Rider lights project is nearing completion.
11:05 PM | Tags: electronics, projects, carMy light panels are complete. 100 LEDs used so far. (I destroyed one testing diffusion methods).
03:46 AM
I just found out, that if you include the work pony in a tweet, you’ll get a response from wheeepony.
04:33 PM | Tags: amusingSetting Discrete States Over a Single Analog Line
While working on my knight rider scanner I came across an interesting problem: how do I get the most state information to the micro-controller using the least amount of wires.
Why would using multiple wires be a big deal, you ask (if you didn’t, you should have). Well, since the area I’ll be installing and routing these wires (my car) is electrically noisy, physically dirty, hot, and let’s not forget the moving parts. Oh yea, then you have get through the firewall. Lastly there is the fact that I don’t want to buy so much wire for simple signaling. Let’s say it took about 15 feet of wire, fully routed, to reach from the micro-controller to the controls - multiply that by the number of states I’d have in the passenger compartment; that’s a whole lot of copper. Sure, I could get N conductor cable to save some green, but that becomes tougher to route.
Rather than complicate things with too many words, I’ll let some drawings I made explain it. Until I get to drawing all this out in Eagle, hand drawings will have to do.
First, we have a resistor network setup as a voltage divider. The extra points are there for a reason that will make sense in a moment. Each option on a rotary switch would be wired so that only one of the M values is connected to the signal line at any one point in time.
M1, M2, M3 are each of the modes that exist for my project. Vcc will be around 12 volts, it can be as high as 14 or as low as 11. Car voltages can fluctuate. One of these networks needs to be on both sides of the signaling wire. On the control side, it is used to set the signal voltage. On the micro-controller side it is used as a basis for comparison.
The following is on the other side of the signal wire. The idea is to convert whatever signaling voltage that is on the line into a format that the micro-controller can easily understand.
Those are comparators. Vs is the signaling voltage (some percentage of Vcc). V2 and V3 refer to the points on the voltage divider above.
With everything setup as outlined above we now have an easy way to know which mode the switch is on. Mode 1 would be 00; Mode 2 would be 10; Mode 3 would be 11.
I am sure this can be expanded to allow for any number of discrete states and the only limiting factors seem to be the precision of the resistors and the number of chunks you can cut the voltage into before the comparators stop being accurate enough. I’d imagine that with a Vcc of 12, you could probably get away with even as many as 12 discrete modes.
Also, in order for this to work, both resistor networks need to be connected to the same Vcc and both grounds have to be the same.
11:52 PM | Tags: electronics, projectsGenetic Algorithms to Design Circuits
A researcher used genetic algorithms to design a circuit and it worked. The problem is, no one knows how or why the circuit works. The system is no longer digital and in fact, uses the transistors in an entirely analog fashion. Pretty amazing stuff.
03:44 PM | Tags: electronicsWow, SNL does it again.
Update: Argh, embedding got disabled. Here is a link to the video: http://www.youtube.com/watch?v=4pXfHLUlZf4
Update 2: Embedding got enabled again. Who knows if it will work whenever you try to watch it.
10:49 PM