>>They provide samples at specific times,
>That definition should be made clear in any discussion of a sensor >subsystem or API, because there are lots of other ways to understand >sensors. The things I use that I call sensors provide samples only when I >ask for them, and if there is any periodic sampling, the periodicity is >provided way above any device driver.
A sensor may sample something a million times/second in a high energy physics experiment, for example. Polling one value at a time doesn't scale well in that case. So those bits are PCI cards that do the sampling at x megasamples/second, batch them and do DMA to the computer proper.
A sensor measures something. I think that's the only thing they have in common ;)