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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@SimonT
On power usage - the gyroscopic effect requires motion, so that's why gyro is significantly higher power than accelerometer. Accelerometer is just a mass on a spring, I think MEMS gyros tend to be tuning-fork type arrangements that are induced to vibrate at a certain frequency.
Therefore it's also likely there's a bit of a warm-up time, and the one-shot call will probably never return reasonable values for the gyro.
@BrianH - if your spindle is fixed, ie there will never be linear motion of it, and you can mount the puck so the Z axis is aligned with the spindle axis, then using purely the accelerometer might be best. In that setup it should measure gravity without any other accelerations (if it's not on the axis you'd get some centripetal acceleration mixed in).
For each rotation the accelerometer value (in either x or y) will basically be a sinusoid - so you can just count a rotation each time there's a sign change from -ve to +ve in acc.x for example. No drift to worry about, power will be lower (if you manually turn off gyro via register), and I suspect maximum supported rotational speed is higher (2000 dps max scale for gyro is still "only" 5.5 full rotations per second, so with an accelerometer at 12.5Hz or above you should be able to beat that).