I've managed to get a prototype working that reads from a NFC enabled glucose sensor attached to someone (Freestyle Libre to be exact) and sends the readings to an iPhone app. The idea is to turn the glucose sensor that requires the user to place the phone next to it, into a continuous glucose sensor by overlaying the device I have made and sending reading over bluetooth to the phone.
Works great, the problem is it really needs to last at least a week, and tests so far show I'm not getting even close to this. Because it's wearable the battery supplying the power must be small.
So far I have the iphone polling every 15 minutes. I scan for the device, subscribe to the characteristic, read the data then disconnect. I'm also putting the NFC reader card into hibernate to save power as well. I thought these measures might minimise power usage however it's not good enough.
It's probably worth mentioning that I am supplying power from a LiPoly battery via the breakout board's voltage regulator. On the final product I will not be using the breakout board, but just the core device, supplying 3.3V via a voltage regulator on the NFC device I am using, so perhaps that will help.
I've read quite a few other posts but nothing has helped so far.
Is there anything else I can do on the Espruino side? Have I missed something?