[rythie]

My guess it's a rebranded Cortex-M3, which would be low-power enough to run continuously. The fitbit flex uses a M3 and it claims 5 days of battery life. I'd guess it stores collected data on chip and iOS copies it over when it wakes up.

[phamilton]

An alternative approach is that it acts essentially as an off chip interrupt. Every time an event occurs it wakes up the main CPU and sends the data over. The main CPU then goes back to sleep. In other words, instead of the CPU having to poll for environmental data, it can be pushed. It may have a small buffer to batch data or it might even be programmable (subscribe to motion events over X intensity). Or it could be just a simple data collector like you described.

[rythie]

My guess is that it would do both of those things. Moves App is something that seems it could make use of both, they've already said they think it is interesting: https://twitter.com/movesapp/status/377507455489433600