I am making an environmental logger that will log temperature, RH%, light levels etc. every 15 mins. I need it to run for 6 weeks off a set of AA rechargable batteries. To achieve this I need to get to sub 1 mA when the 328 is asleep.
Data are collected and written to an adafruit microSD break out board - along with some progress LED's this uses about 25 mA. I can initialise the SD card, write some data and then sleep the 328 with the narcoleptic.delay command but even when everything is off the SD card is still drawing 4 mA and then the logger only runs for 7 - 10 days. [I know it is the SD breakout because when I pull it out current drain drops to 0.4 mA]
To shut down the SD card I have tried switching off the ground line from the card using a switching transistor but the microSD card still draws current. I have tried file.close and then setting pins 10,11 and 13 to input to stop any current drains. This works in that current drain drops to 0.4 mA but .....
I cannot re-awaken the SD card. sd.begin does not work - returns FALSE. SD.open is accepted but file.print does not add anything to the file.
Any one else had experience using SDCard breakout boards and the narcoleptic library?