ECE497 Project - Grainbin Monitor

Team members: Thad J. Hughes

Grading Template
I'm using the following template to grade. Each slot is 10 points. 0 = Missing, 5=OK, 10=Wow!

 00 Executive Summary 00 Installation Instructions 00 User Instructions 00 Highlights 00 Theory of Operation 00 Work Breakdown 00 Future Work 00 Conclusions 00 Demo 00 Late Comments:

Score: /100

(Inline Comment)

Executive Summary
This will monitor the level on grain bins so a farmer can see how much more room there is remotely, and will also alert them (via text, phone call, or push notification to a smartphone) if overflow is imminent. It should be cost-effective (sub-$100) and portable as opposed to other solutions which are permanent installation and quite costly.

Packaging
This should end up being a unit which is POE connected (since grain bins are effectively faraday cages, Wi-Fi onboard will likely not work), dust-proof, and magnetically attached with a steel tether for retrieval.

Theory of Operation
This will use an ultrasonic or laser distance sensor (or a few of them) to measure distance from the unit to grain. From this and a known (user-specified) bin diameter, the bushels left can be approximated (with angle of repose being roughly the same as the bin's roof). Notifications could be accomplished with SMS systems, and monitoring with Blynk; other implementations also exist.

A MB7092 XL-MaxSonar-WRMA1 sensor is used, with serial (RS-232) communication. This sensor is cheap, available, weather-resistant, and measures up to 25 feet (not the full height of a grain bin- but it measures the range that is of interest).

`The baud rate is 9600, 8 bits, no parity, with one stop bit.`

This means it must be setup as: `stty -F /dev/ttyO1 cs8 -parenb -cstopb`

However this is RS232 "from 0 to Vcc", not TTL. So this isn't quite so plug-and-play, but can be easily made to work with an inverter- and it does!

The sensor is a little "wonky" but it does detect large surfaces rather well.

With the setup correctly, the device is connected to Blynk and logs data as fast as a device polls it, but I would like to both log the distance over time, and do it automatically.

I would also like to do some filtering on the data (as well as have notification "arming" that is shut-off whenever the first notification is sent), so that brief erroneous readings do not cause a notification, and you are not spammed with notification as it fills.

I created an enclosure for the device. Whatever material I made it out of doesn't mill very well... nylon would have been a better choice, but that's what I get for dumpster diving.

The device is wired up such that it takes power-over-ethernet (at 6-25VDC). This way it works like typical Ubiquiti devices which many farms use as their networking solution of choice.

About this time, I'm starting to have my bone spontaneously shut off after a minute of uptime. This could be related to the power regulator, since the 7805 chip was not heat-sunk and upon investigation, was getting quite hot. It could also be a corrupted SD card image. We will need to have a boot-down switch on the device, as well as power and status indicator LEDs!