Low Energy WiFi Datalogger

Community Projects
1

Hi Guys, as the subject suggests I’m trying to build a low energy data logger which will periodically send the datalog to Dropbox(or google drive or whatever) over wifi.

My plan is to use a Logomatic v2 with an Arduino Yun. To save power I would like the Yun to only turn on once per day, connect to wifi, read/send the data from the Logomatic v2 microSD card and shut down again.

Does anyone know;

  1. Is possible to use the Logomatic v2 to provide power to a Yun periodically(roughly 5-10min per day) or are its abilities strictly limited to datalogging?

  2. Any other way of achieving this periodic power-up/power-down of the Yun?

I’m very new to this so any help or thoughts would be great! Thanks!

2

Hi,

First off, I am a noob too :slight_smile: However, I am working on a data logger myself, using the Logomatic v2. There are two 3.3V and two GND pins on the Logomatic that you can use to power other devices, as long as the Logomatic is actually ON. This is what I am doing in my setup. I am not familiar with the Yun, but it looks like it may run off of 5V; in which case you’d need some sort of boost converter to step your output up to 5V. There are sleep libraries for the Yun that you can use to conserve battery power. I have been researching this myself, but ran into a snag: the Logomatic itself draws about 65 mA of current, and I’m not sure if there is any way to significantly reduce this. There is no real “sleep” mode for the Logomatic of which I’m aware, so even if you CAN put the Yun to sleep, you’ll still be drawing a lot of current from the Logomatic. Also, repeatedly turning off and on the Logomatic’s input voltage would, I believe, keep creating new files endlessly. I have emailed technical support, and am awaiting a response.

One alternative I have been looking into is the OpenLog, which apparently only draws about 6 mA, and I think would be more compatible with sleeping to conserve energy. The only thing with the OpenLog, which I am still researching, is whether or not you can read any data from it in-situ, or if you absolutely have to manually remove the SD card and plug it into a computer.

From my research, one thing you can probably do with the Yun to achieve periodic power-up/power-down (which I am going to do in my project) is to write code that puts the Yun to sleep, and then use an external RTC to send a periodic signal that will wake it up.

I hope any of this helps you, and again I’m a noob, so take it all with a grain of salt.