Using easy to locate parts and a Raspberry PI 2 to create a game of recycling
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Code for The Less Waste Game will be published at https://github.com/jdarling/lesswaste once I get the initial version somewhat working.
Still making decisions on the hardware, think I might just go with ordering load sensors, can't find cheap scales.
Got all the parts in today, not bad considering they were not scheduled to be delivered until June 19th. Unfortunately I didn't read well enough and the 4 wire load cells I thought I was ordering were actually only 1 single 4 wire load cell. So, that isn't going to work at all.
Fortunately, what is going to work is the other 3 wire load cells I ordered. They came in a nice pack of 4 and I think I can make them do exactly what I want.
I also ran across some really great articles on using the HX711 directly with the Raspberry PI, so no more need for an Arduino in the mix (yea, less parts)!
Just in case its useful for others, here is what I have found so far:
http://hivetool.org/w/index.php?title=Interface_the_HX711_to_Pi (HX711 with the Pi)
https://github.com/ggurov/hx711 (HX711 library for the Pi)
Hopefully over the next couple days I can figure out how all this is going to go together and then I can get on to devising how exactly I plan on using it :)
Don't ask me why I haven't uploaded the system overview diagram before now, but I didn't. So, I uploaded it today.
I hoped that my new parts (load sensors) would be in before the end of may, but due something in the shipping they are stuck in China. Hopefully they get here soon as I'm getting to the point that I need the real load sensors here so I can complete the hardware.
I know I haven't put up any updates in a while so I thought I'd at least put up an update saying I'm still working on this project. I've been devoting most of my time to getting the RPi working with the Arduino to communicate and read the ADC. This has proven to be a bit more of an undertaking than I initially thought, but it has been good learning experience. Once I have code working I'll post the followup with code and details.
The ADC I settled on is based on the HX711 and can be found on Amazon (http://smile.amazon.com/SMAKN%C2%AE-Weighing-Dual-channel-Conversion-Shieding/dp/B00M6POINC/) for ~$7USD. It can handle two analog channels and will work well for the trash to recycle bin differential. Granted at the larger end I'd like to add another one of these to allow for different types of recyclables to be measured (Glass, Plastic, Paper) but for now I'm working with just one.
As for load sensors, I'm playing with several different ones I got in different bathroom scales. Most are the typical 3 wire variety and look very similar. I've also ordered a set of 4 wire ones from Amazon (http://smile.amazon.com/Electronic-Weighting-Sensor-pressure-transducer/dp/B00VV4RN3Q) as well due to their low cost and the fact I want to see how different they are. The only concern I have is they are 2 hole setups and I have no clue where the deflection point is, but that should be part of the fun :)
Anyways, more details as I make progress.
Started setting up the code repo on Github (https://github.com/jdarling/lesswaste) today. A lot of work to do, but after about a month of thinking about things I think I have the initial plan worked out in my head.
I think I'm going to model the game part of this from traditional resource collection type games where you will produce resources for each week that you recycle stuff. Trash weight is taken as consumption of resources along with some other general information. Still a lot of grey to work out, but my initial though is something like the carbon footprint as the scale itself.
More as I work it out, on the good news side of things, the Pi works perfectly and I've got it all setup to actually run the software.
Moving this from the comments section to the build log section where it should have been.
Started looking into how exactly I'm going to connect the Pi to the load sensors. Since the Pi doesn't have any real built in analog ports available will probably go with a simple A->D setup. Will test different options, but high on the list is a simple RC setup to measure the charge discharge times to get a rough value back. Should be good enough for the simple game approach I'm planning.
Also haven't decided if I'm going to go with a scale and steal the load sensors or just one of the inexpensive load sensors available all over the place. Will depend on if I can find a good sale on scales :) Either way the generals are the same, hook to the load sensor, record the resistance, compare it to a known value and judge the weight.
Did start to work out some of the physical needs like "buttons" to "tare" the containers, lock a weight for things like emptying a bin before weeks end, and reset at end of week to "submit the score"
Of course, may just make it a touch screen interface. Still have all the stuff from the baby phone that proved to actually be a small display with a built in resistive touch screen. Should be easy enough to hijack that in.
jeremy.darling
Nick Verlinden
Lars Knudsen
Nate Schroeder
Timo Birnschein