You can buy a USB to serial port adapter, but unfortunately they do not seem to be universal - why, I don't know. I was trying to find one to use with my GPS and I ended up buying three different ones before I found one that would work with my laptop and my GPS. Some of the others would work with other serial devices I had, but not the GPS and vice-versa.
If you can get a serial cradle that will also work. It's what I did with my Handspring. It needs a little modification from the basic pinouts. The setup uses the PC, not the Handspring, to power the serial port. You need to give a few pins +5 to attach it to anything else besides a PC.
The Orion trackside unit has an IR receiver but no IR transmitter, so it could not communicate with a Palm. In fact, it is not just as simple as using an IR transmitter to communicate with a Palm... there is a lot more going on.
You seem to have a good understanding about a lot of this. Do you have any designs for a smallish 100 Hz datalogger circuit that would do 2-4 channels (SE or Diff)? I have looked, but they either sample at about .5 Hz or need power from a PC (USB powered).
The thing to do would be to start with a microprocessor and attach a large wad of EEPROM. You can upload to a PC via serial. Sense the servo commands from the pins, use an A/D chip for voltage and a Hall sensor for current. Sounds like a good project, but not one I want to tackle while the other things are unfinished...
It would be pretty hard to go at 100Hz, the amount of data to be stored would be huge. That is about 200K of memory required per minute. It is 400 pieces of info per second so you are actually looking to operating at close to 4000Hz with the overhead (read, convert, write, etc.).
Something that samples at 5 Hz would be easy with 10Hz not much harder. Of course it would all have to be custom built... very doable but would take some development time. To make sure there are no problems a seperate battery pack would need to be used. Not really that bad as many already use a receiver pack and that could do double duty to power the unit.... 6 cells would be better then the 5 cells that are normally used.
What I am actually looking at doing is making a "real time" DAQ where the data would be transmitted via RF to a computer in real time. Then you could let the CPU run at full speed and sample as fast as it, and the program, would allow and not worry about data storage. I figure it could do 6 channels at least 50 Hz, most likely more.
This is something that I believe could be VERY useful to R/C car racers. The Miles brothers have done something themselves, but I hear it has been fairly pricey. I would like to work this out, but circuit design is for me.
If you plan to develop this for sale, keep me posted. If not, consider what you would charge me to make a couple units.
The plans for anything I design will be freely available to anyone. I may offer a "parts pak" that would include everything needed to make it. That would save someone from having to buy from a half dozen suppliers and would also include a circuit board to mount everything on. My guess is the cost would be less then $300
I want a RPM sensor on my personal data logger... I thinnk with RPM I could tell most of what I'm missing... Voltate and Amp would be nice too, but I could likely live without that, if we were talkinga bout something cheap...
Oh wait a minute... this is the personal lap counter thread... could you throw a RPM logger in with it?