A few weeks ago I was chatting with my mail carrier who is also a beekeeper. I mean LOTS of bees with some hives in remote locations. He has a friend that is working on a system that weighs hives and sends data over WiFi to a beekeeper’s desktop computer or server. The most important data is the hives weight although temperature and humidity are also useful. This system is good when the hives are close to structures with usable WiFi but useless in more remote sites where there is no accessible WiFi. I suggested that his friend investigate using cellular telephone SMS text messages instead where many more hives could have their data monitored.
I mentioned that I have just been reading about a small printed circuit board that could be used with an Arduino that would be perfect for remote beehive monitoring. It is an evaluation board called “SIM800L EVB”. They are available on eBay in the $6-to-$10US range. I purchased mine from Philippines seller “holi_day_sales“. I was careful to purchase a version that has on-board voltage regulation for that I could use five volts. Some versions have USA frequencies and others are for Europe of Asia. Caveat Emptor – they are NOT all alike! They were also available from Seeed Studio but they currently seem to be out of stock. In any case, Seeed’s wiki is useful. A remote solution is possible if the hive has at least one bar of AT&T cellular telephone coverage allowing communication by SMS (TEXT). Such a solution would have a reduced parts count to a single microcontroller, such as an Atmel ATtiny84 (Prototypes could use an Arduino board), sensors for weight, temperature and humidity, A solar panel with battery and charger would provide power.
I’m not sure if my mail carrier’s friend will pursue using SMS text messages for his hive monitoring system but, nonetheless, I became interested in testing the little “SIM800L EVB” board, which is exactly what I did this afternoon. I’ve only done a little testing but the SIM800L performed with flying colors. It is very easy to work with. I cheated a bit and relyed on Ayoma Wijethunga’s excellent blog article titled “QUICKSTART SIM800 (SIM800L) WITH ARDUINO“. You need little else to get started with the “SIM800L EVB”.
For my tests I used a H2O Wireless GSM SIM card. Specifically, it uses the AT&T GSM cellular network but is marketed by H2O Wireless at $10 for 90-days of service at 5 cents per text message sent or received. That allows two text messages to be sent per day. They also sell more expensive plans should more data be needed. I surmised that, by omitting extraneous characters, a single text message could easily hold a hives weight, temperature and humidity. For example, a hive weight of 125 pounds at 72 degrees Fahrenheit and 30% humidity can be represented by the nine character string “125072030” using three digit positional data of three characters each representing “Weight in pounds”,“temp in Fahrenheit”,”Humidity in percent”. Given that a single SMS message can contain 160 characters, a single message has another 151 characters available for other data, should it prove necessary. One possibility would be to have one message represent the data of 17 bluetooth networked co-located hives that share a single SIM800L board.
So, below are images of one of my tests. I am sending a simple “Hello World” type message from the SIM800L board to my Android smartphone. I sent “Hello,World from Seed” because I used the Seeed library, but the SIM800L module is NOT a Seeed module.
By the way, the test setup shown above has some extra components and wiring present because they are for something else that I am working on and I wanted to leave them in place for that project. Also, the little rubber-duck antenna is propped in a vertical position by the blue Ethernet cable that also has nothing to do with this project.
I should point out that there are commercial products that do something somewhat similar, although at a price that may exceed all but large commercial businesses. For example, see: http://colonymonitoring.com/cmwp/whats-available/commercial/