FUTURE CHALLENGES :
As you know from above : I am building a data logger on a remote farm which measures voltages and currents for the solar /wind system there. People are not on the farm often ( every 2 weeks ) so there is no way of knowing what goes on with the solar so I thought to monitor it with a YUN./SD card and a wifi ( if possible) . The YUN will run off the 12V power from the solar cell .
I read the YUN doesn't have a real time clock :
Federico asked whether it would be useful. Considering the cost I think yes very useful ,2 reasons : .
a) SLEEP and NO wifi = NO time : I need to turn the Yun data logger on only once per hour every hour (or 30 min etc ) . This will save much power if I could send it to sleep completely and wake it for 2 minutes every hour . Ideally, during wake time it will transmit this data collected to the SD card for safe keeping and if a wifi is made available to pass it through temboo and a google spread sheet .
To get around this ( unless somebody has a solution ) I was thinking of using a very low sleep powered chip like (uAmps in sleep state with a real time clock ) to run a relay to turn on the YUN and monitor an output of the YUN to turn back off once data is collected. A real time clock though could be so handy in turning most components off for X amount of time.
b) Accurately logging the data points in date time (if no wifi ) . Without a wifi accurate data logging can not be harnessed.
The second issue I have is that there is no WIFI on site so I need to write my data on SD card so that is a half a solution.
The neighbour is about 100 meters away and he has wifi at his house . The area is sparse so I assume very little electrical noise . He ,in principal , has no objection to the yun being on his network and my vision was to use the YUN to write values of data ON SD CARD to a google spread sheet via TEMBOO.
So my challenge is
a) trying to get a cheap wifi link to his place at such distance with the YUN .
b) and developing some way of knowing when the wifi is connected to dump what has not been sent to google sheet using temboo.
eg: Lets say the YUN boots up 3 x over the next 3 hours and for some reason does not get wifi .. it must then on the 4th hour when connection does happen needs to dump the last 3 hours of data . So this case of predictable wifi is not assured maybe not even possible with the distance factor.
IDEAS : I am guessing the only way I may be able to get data to the neighbour is :
a) Use some kind of arduino like board at the main site doing the measurements and a transmitter and send data to his place via a receiver and YUN near his house ?
Any ideas welcome :-)