Hi everyone
I was wondering if it is possible to save lots of data( exp: one year data) in data logger shield and then read them from serial port without ejecting the SD card... this part of my question is fine... the main subject is that i want to read specific date's data from the logger... To explain this better, lets say you have a humidity sensor and saved it's data for a year. Now you want to send the last 6 month's data to your phone via bluetooth. Is it possible? Also, i wanted to use the circular buffer but that doesn't seem like a good idea because it's costly... any ideas will be such a great help.
On several projects I have split the log data into specific chunks of time to log to an SD card. In other words, depending on the volume of data you are writing, each log file could contain 1 day, 1 week, or even 1 month of data. In my projects this made it easy to remove the oldest data as the SD card filled up with data. It also made it easy to retrieve data.
Make sure each file name includes a time stamp formatted in such a way to make sorting by time easy. Each line of data logged within the file should have a time stamp as well.
All of this depends on the amount of data contained in each log entry and the frequency of the logging.
ToddL1962:
On several projects I have split the log data into specific chunks of time to log to an SD card. In other words, depending on the volume of data you are writing, each log file could contain 1 day, 1 week, or even 1 month of data. In my projects this made it easy to remove the oldest data as the SD card filled up with data. It also made it easy to retrieve data.
Make sure each file name includes a time stamp formatted in such a way to make sorting by time easy. Each line of data logged within the file should have a time stamp as well.
All of this depends on the amount of data contained in each log entry and the frequency of the logging.
That sounds fine and i wanted to do that, but is there any way to get any period we want? for example i want the data between 10-20 days ago...
and another question.... how did you rewrite to each file you specified for different time stamps?
Farnaz_201:
Now you want to send the last 6 month's data to your phone via bluetooth. Is it possible?
Yes.
Create a new file every day at midnight using date as filename. Download using the DumpFile example in the iDE by sending the relevant date from the phone. All done over Bluetooth. You might find the following background notes useful.
http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf
http://homepages.ihug.com.au/~npyner/Arduino/BT_2_WAY.ino
An example is included. Strip out what you don't need.
Also, i wanted to use the circular buffer but that doesn't seem like a good idea
It probably isn't. It is certainly unnecessary.