Smart Lighting


This post involves an old passion of mine, computerizing homes. First some background. I spent the academic year 1975-76 on sabbatical at the Max Planck Institute for Solid-State Physics and the University of Stuttgart in Stuttgart, Germany researching nonlinear laser spectroscopy theory, generally of atomic media. But the Max Planck Institute aroused my curiosity about solid-state media and particularly about semiconductor media. During this time I learned of the Intel 8080 microprocessor which seemed incredibly interesting to a computer nut. So after returning to the University of Arizona in Tucson, I just had to check out microcomputers. On Christmas Eve 1976 I drove up to Phoenix and bought an IMSAI 8080 microcomputer kit for $2500 with 16K of dynamic RAM. It took a couple of days to put it together. Soon after I swapped out the Intel 8080 CPU card for a more powerful Z80 CPU card and added a whopping 48K dynamic RAM card (much against the advice of one of my physics colleagues). I even keyed in Bill Gates’ 4K Basic using the front panel switches! Clearly I needed a keyboard, so I bought one and wired up an interrupt circuit so that the computer didn’t have to poll the keyboard all the time. A couple of years ago I looked inside my old IMSAI Z80 and 90% of the circuitry is wired wrapped! Talk about customization. There are lots of fun stories about the early microcomputer days, but I digress. Pretty soon I decided I wanted to learn more about semiconductor technology and decided to computerize my home. Maybe it could become a business; no one else was computerizing homes back then.

To learn about semiconductor circuits, I opened my copy of Kittel’s Introduction to Solid-State Physics expecting to find good explanations as to how diodes and transistors work. This famous text book didn’t even mention semiconductors let alone diodes! So I bought Don Lancaster’s nifty TTL Cookbook and learned a lot. Pretty soon I was wire wrapping up reed relays to run silicon controlled rectifiers (SCR’s) to turn on lights controlled by my IMSAI Z80. I wired up a front-door keypad to open the front door. My daughters never needed house keys; they just typed in the entry code and presto, the front door opened. I got involved with garage door openers, which were made in nearby Nogales, Sonora, Mexico. It was easy to get the openers to communicate with the IMSAI Z80 so that I could walk up to the front door, say Open Sesame (افتح يا سمسم‎)! And sure enough the door opened (secretly I pushed a button on the garage door opener in my pocket). I could also call into my computer from anywhere in the world and enter a code telling it to open the door or turn on the lights. At night I could enter a code on the keypad by my bedside and all the lights in the house would turn off or on. And while we were away, the lights came on and off just as if we were at home. I dremt up plans to have a security service monitor houses including things like notifications when water was on the bathroom or laundry room floor or smoke was detected in a room.

But there were problems with all this functionality basically because a practical infrastructure wasn’t available. I ran something like two miles of wire throughout the house. My daughter Tina ran some of the wires for me because she was small enough to fit into the crawl spaces above the ceiling. Yeah, I know, child abuse! But she seemed to enjoy it. Running so many wires clearly was cost prohibitive. Local area networks existed at the time, but they were very expensive and hard to interface to sensors and other devices. WiFi was unheard of. The X10 protocols for turning on lights and other devices over the power lines was available and I wired up a card to control X10 devices with my IMSAI as well. From a data rate point of view, X10 is really slow because it doesn’t know how to avoid power line noise except by being slow.

After a while I realized that computerizing homes was a very fine goal but that it was simply beyond the state of the art in the 1970’s. You could do it, but it’d cost $100,000 or more depending on how elaborate you wanted to get. Bill Gates must have spent millions computerizing his Lake Washington mansion many years later (1990’s and 2000’s), but he went way beyond what I had done both in functionality and in size.

So how could I take advantage of all this microcomputer knowledge? One of my colleagues at the University of Arizona Optical Sciences Center, Rick Shoemaker, had used a microcomputer to computerize his experiments and take data night and day. We decided to write the book Interfacing Microcomputers to the Real World. The book has an introduction to TTL logic and explains how to build a microcomputer from scratch and to interface it with a variety of devices. It was the first of three books we wrote about microcomputers, the most recent (and not very recent) being The Personal Computer from the Inside Out. It's great that Amazon has all these books for sale!

Fast forward to the present. The cost-effective infrastructure is almost available now and the features are simply marvelous. At dinner a week ago I naively mused that LED lights use semiconductors, so why not make them smart? Talk directly to the lights and bypass smart switches, which can be a pain to install in junction boxes built for dumb switches. A little Internet searching revealed that people started making such smart light bulbs several years ago. These include the Lumen, LIFX and Philips Hue bulbs. The bulbs aren’t cheap (typically $60 each), but they last many years and they are way easier to install than changing out wall switches. You can control them with your computers and your smart phones (who ever heard of such a fabulous controllers back in the 1970’s!). And just last month Stack upped the ante by introducing the Alba bulb with built-in smarts. Notably, the Alba bulb has a motion sensor which lets it turn on and off automatically depending on occupancy. Stack’s hope is that switches will become a thing of the past or at least much less used. All of these bulbs can emit light with various colors and hues, so you can have sun-light white, soft white, red, blue, or whatever color you want. The Alba bulb takes the time of day into account to choose appropriate choices of white, such as sun light in the morning and warmer light in the evening. You can fine tune the behavior with your smart phone or computer. With its motion sensor, the Alba bulb also acts as an iBeacon, identifying the presence of a moving being. This can be particularly useful in commercial environments, but can also be valuable in home security systems. What a cheap motion sensor!

A home-automation network such as ZigBee is typically a bit different from WiFi. The idea is that the data rate for home automation doesn’t need to be large as it does for WiFi, so controllers and devices don’t have to use as much power to communicate. The home automation industry is very power-saving conscious and smart homes can be much more energy efficient than dumb homes. In fact, in addition to being much more people friendly, smart homes will probably be considerably cheaper in the long run even including the initial expense of smart light bulbs, ZigBee controllers and other infrastructure. In addition to turning off the lights when no one is around, power intensive usages can be automatically scheduled for times with cheap power rates. And you can tie all kinds of gadgets to the network, like cameras, water sensors, smoke detectors, appliances, robots, you name it!

These advances haven’t gone unnoticed by large tech companies. There are numerous smart home companies, such as Insteon (Internet search finds lots more). In addition some cell phone companies are getting into the act as evidenced by Google’s Nest and Apple’s HomeKit. Cell phones make great controllers for the home. They’re even useful for making phone calls, although frankly a land phone has considerably better audio quality. Looks as though my dream of inexpensive computerized home control will become reality pretty soon! Hey it’s only forty years after I tried and there are lots of exciting enhancements in addition to being economical.


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