Hi On Aug 24, 2013, at 3:27 AM, Hal Murray <[email protected]> wrote:
> >> If it were me, I remove the LCD display. I don't see a need when everyone >> today has a phone. the little AVR chip can bit-bang a UDP packet once per >> second and put it on your wifi router. That cuts the parts cost by 1/3rd >> and the display will be where you can see it, on the phone or computer. > > There are still a few of us who don't have cell phones. :( > > I split the problem into two areas: > Collecting the data > Displaying it > > If I'm collecting data, I want to be able to look back over hours, days, > months, or even years. That means I probably want to backup/archive it too. > > 100 characters of text every 10 seconds is under a megabyte per day. That's > small relative to modern disks, medium relative to thumb drives or SD cards > and small to medium relative to RAM (or ramdisk). [I generally chop things > up into a file per day.] That's a *lot* more than a simple monitor. Once you get past "simple" you already have LH and a lot of hardware that will run it just fine. Bob > > So far, I've always had a handy Linux box running 24x7 when I wanted to > collect data, so I've never tried to use a smaller system. Since the data is > collected on a real system, it's easy to display it any way I like. > > I won't be surprised if a project comes along where I want something like a > small uP to grab careful timing data. Until then, I'll keep collecting my > data on a real PC. > > ------------ > > Does anybody have data on lifetime of Thumb/SD cards if you flush a log file > every 10 seconds? > > What type of file systems are supported with whatever OS comes with small > uPs? Is there any work on flash-friendly file systems for append-only log > files? > > A year or 3 ago, I did some work on logging to ramdisk and occasionally > copying to hard disk. The idea was that the hard disk would be spun-down > most of the time, saving a lot of power. It didn't save much so I bailed on > that project. I assume that means the power to keep the disk spinning is low > relative to the power to keep the electronics going. Maybe I just botched > the experiment. > > > flushing the file after each line is the simple way to make (mostly) sure > that your data gets to disk in case the system crashes, but it turns into > several disk writes each "line". That's no big deal for a lightly loaded > hard drive but gets interesting in terms of total writes to flash drives. > > You could, of course, fix the code to only do the flush once every N minutes, > or only when something interesting happens... > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
