Recipe for long battery life using nRF51822?

[sanjivkumarca]

I would like to create wearable fitness based applications/hardware using nRF51822. But i am not sure how to get the fullest of power down modes in the chip. For example, i am amazed by the MiBand battery life with over a month without charging. How to do you keep monitoring accelerometer readings; log them if any change and go to sleep if no change; turn off bluetooth radio if not paired to phone ? and only wake up during a Bluetooth search. Could anybody explain how i can achieve this using nRF51822?

[Vidar Berg]

Hi, I would recommend having a look at the nRF51 current consumption guide for general information on power savings. I haven't worked with accelerometers in the past, but I think some have an IO pin that is asserted on movement, which could be used to wake the device from system OFF to reduce consumption if that fits your use case.

[Dan Danknick]

Vidar is correct on the accelerometer, all modern ones provide a method to generate an interrupt when a threshold is exceeded. Fortunately they consume very little power - some are so low you can actually power it from a GPIO pin if you wish.

I suggest you build your prototype to focus on your algorithms before being overly concerned with battery life. You may be surprised just how hard the accelerometer processing is to yield the data you wish - you may not even get to the point of optimizing for battery life!