Since my last update I have made a great discovery. I found the following youtube video that explains how to use the TV Out library. http://www.youtube.com/watch?v=WlBXiZpuncg
It is ultra simple I know, but I just found it and it is absolutely perfect for my project. It just so happens that part of the buildup for our new trucks includes a clamp on TV monitor to be used with a back up camera. They are very cheap and basic, but they have a aux composite video in! Also the new trucks have 3 or 4 aux switches and I am considering hijacking one of these for my system power. I am not sure if it is possible with memory limitations, but it would also be fun to include a few of the basic games to be access via a backdoor (need help here).
As was the case when I was designing my first website while learning html the design is evolving rapidly as I find new limitations and capabilities.
While I have not hooked it up yet I have received a 5v Pro Mini from Sparkfun and their usb interface. When I get a working design I will be making from 2-6 of these. I think I would still like a full Arduino (vs just the parts I need) to allow for future features and expansion.
The circuit will now also include an air solenoid (maybe two for calibration) and an air regulator. In all of my installations I will have ~90psi available and need to get that down to 7psi.
The sketch is still running a calibration and then displays a series of bar graphs. Since I only have 3 transducers so far the other two inputs have pull down resistors to prevent float.
The technicians in the trucks will likely be happy with the bar graphs, but the owner wants to know how many gallons of liquid are in each tank. I will need someway to do the conversion that can be easily tailored to each tank on each truck as they are all different. I would also like to swap displays between the bar graph and the detail output.
-I am envisioning a future where a click on a website triggers a read on all of the sensors on all trucks (and the warehouse) and returns a spreadsheet with all totals and re-order points. This will of course require a way to network them, but it is way too much for my MVP.