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Logging Bluetooth Accelerometer Data on a PDA?
sessha asks: "I want to log data from a Bluetooth Accelerometer (actually 5) attached to different parts of the body. How one would go about logging the data onto a bluetooth compatible PDA. I know quite little about PDA OS's, but the main concern is functionality - it doesn't matter if it is PalmOS or Windows CE or whatever. The Linux and Windows directions for data logging are shown, but how would one best go about this on a PDA? Also, it would require at least 256 MB storage, preferably more, since this will be recording 300 of these ASCII strings a second for a number of days. Suggestions as to the best equipment and software to use for such an endeavor would be greatly appreciated."
lets see, 16 bytes / string at 300hz gives us
16*300*60*60*24 = 414720000 bytes/day or about 400megs / day
If instead you use a simple binary representation with 6bytes/record we get
6*300*60*60*24 = 155520000 byets/day or about 150megs / day
I bet the data would compress really well, but if a pda would have enough horspower to log and compress is an open question, I would guess yes.
ps
If you want to play with bits and save 2 more bits per record then we get:
5.75*300*60*60*24 = 149040000 bytes/day
Thoughts on tech, Software Engineering, and stuff
The other issue you'll want to look into is battery life. I was talking just today with someone from PalmOne about their models with an eye to finding something with a long enough battery life to be used for a week without charging in a 25% utilization scenario. They don't have such a beast. They spec them for about 10 hours of normal use, but heavy data logging isn't normal use - it's high memory bandwidth and that will cost you power. On the flip side, you don't actually need the screen running, so if you can turn that off it will help.
Given that WinCE based devices are generally known for shorter battery lives, I'm not so sure that your request is practical with current technology.
Now, what about an Ipod-style device? They have big hard disks, and they're designed to run for many hours. That's where I'd be looking - either that or those new-fangled 'wearable computer' things that have a hard disk and a bluetooth adaptor and can be thrown in your bag to allow you to access your personal storage at any computer.
the 5500 is a pocket linux workstation. it will run most linux software, particularly the non-gui/server oriented stuff, just fine.
/var/log/bluetooth_capture.log style files later when you get back to home base, where you can use rsync and such (over WLAN) to snarf the capture database/logfiles ...
...
put a big CF storage card in it, and use any one of the various bluetooth hacking/logging tools to put all received packets into an onboard mySQL database, or just prune some
really an easy project, and cheap. the 5500 is an underground hit with linux folks for good reason
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
All the tools and SDKs for doing this with a Microsoft Windows powered PocketPC are available for free download.
Windows Mobile downloads - start here.
In particular, the Windows Mobile 2003 SDK will be of interest, as will the eMbedded Visual C++ IDE & compiler (don't forget service pack 3 for it).
There are a dizzying array of other tools and SDKs available from that site, so take some time to read everything. There's also a PocketPC emulator for Windows (not sure if that's included in the eMbedded VC4 link above, but it was included in eM VC3). All tools (including the IDE and compiler) are absolutely, 100% free.
Suck it down, Palm.