Home automation is a really neat use of technology. Automating the process of turning off the lights when you leave the room is nice if you're a tad lazy like me, and also is a way of being kind to our Earth by saving energy!
I started this project mainly as a segway into teaching myself more about the MSP430 family after I was inspired by a college course in embedded systems last year. We learned how to program the family in C++ and Assembly, but really only scratched the surface. It has been a challenging yet fun project and has helped me veer away from the Arduino.
So without further ado, here's an explanation of what this Instructable aims to show you how to build:
The room visitor counter (as you might have expected...) counts how many people are currently in the room, given this room only has one means of entry. We're not talking firepoles here - I mean a doorway. When there is at least one person in the room, the relay is switched on. And vice versa, if the room is vacant, the relay is switched off.
Using 3 blue LEDs, there is a binary count (I didn't have a 7-segment LED display/display driver at the time I built this) of how many people are in the room, with a maximum displayable count of 7 (when the count is incremented past 7, the LEDs simply remain on).
In this instructable, I assume a level of ability in soldering and prototyping skills. The detail in this instructable is on a higher level of abstraction. In other words, if you can solder, read a schematic and are comfortable downloading some software, you can do it!
Step 1: Making the Backplate
First off, we need to build something to hold it all together. I could have opted for an enclosed case, but I started off simple. If you are feeling adventurous, it wouldn't be a bad idea to enclose this in a box for better protection and visual appeal.
Here's what we'll need for my bare-bones hardware build:
* 3/16" thick plexiglass
-->This is cheap yet study enough to keep this all together (plus, I use plexi for everything)
* 2 threadedstandoffs, metal or plastic
-->These are for securing the circuit board (PCB) to the backplate
-->At least 1/4" long; I used 3/4" metal standoffs because that's what I had. 4 would certainly work better at securing the PCB
* 8 4-40 screws, sized to fit your plexiglass and standoffs
-->Make sure they are long enough to clear the plexiglass, PCB board, and then thread into the standoffs at least 1/8"
-->We'll use 4 of these to mount the PCB
* 4 nuts, sized and threaded to fit the machine screws
-->These are for mounting the IR sensors
I cut the plexiglass from a larger piece using a tablesaw. Since this is just plastic, you should be able to get by using any type of blade.
The dimensional drawing can be printed in 1:1 scale