https://devzone.nordicsemi.com/f/nordic-q-a/9640/heavy-calculation-could-make-battery-life-shorterHi, I&#39;m making device with nrf51822 chip and 400mA battery. It connects to smart phone. It has to calculate heart rate and some other things, so it&#39;s doing it on device side(it has to do work without connection with smart phone sometimes) and I thinken-USTelligent Community 13Fri, 09 Oct 2015 07:45:07 GMThttps://devzone.nordicsemi.com/thread/35630?ContentTypeID=1Fri, 09 Oct 2015 07:45:07 GMT137ad170-7792-4731-bb38-c0d22fbe4515:16a5dba3-eaf4-4e60-afab-0c3a13e572a0Susheel Nuguru<p>fitbits does BLE communication like any other low power gadget. I am not expert in their operation, but i would think that they make the cpu go to sleep majority of the time and let all the calculations in the application inside the peer device(phone or other gadget with more battery power). The basic idea of BLE is to transmit as little as possible (and sleep immediately) to the device with more battery and allow it to make calculations.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/35632?ContentTypeID=1Fri, 09 Oct 2015 07:33:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:adf7a5f8-adc7-4f1c-8a32-293ca14c5b99benevbright<p>How about fitbit? to calculate steps, I think they should keep device&#39;s cpu active all the time but their battery life is so long. OK maybe not all the time. when it detects that user walks.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/35631?ContentTypeID=1Fri, 09 Oct 2015 07:31:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c1fd2e28-9e5b-47e1-8986-8a49a22de6c1benevbright<p>Oh great help. Thanks. Then is there any way to make cpu inactive by firmware code? sleep(XXXX) makes cpu inactive?</p> <p>Thanks for help.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/35629?ContentTypeID=1Fri, 09 Oct 2015 07:21:35 GMT137ad170-7792-4731-bb38-c0d22fbe4515:28fecaac-f8d0-4cb2-a3fe-9a00c533a2c3Susheel Nuguru<p>Its not about heavy calculation, its about how long those calculations are keeping the CPU active. Heavy calculations are not different than any other CPU instructions (as nRF51 does not have FPU) If the calculations are keeping the CPU active half of the time that is heavy draining of battery. I have tried beacon module to keep active all the time to see how fast it drains the battery and keeping the CPU 100% active drained a lithium coin cell in 5-7 hours.</p><div style="clear:both;"></div>