Design idea for saving battery life in nrf51822/SDK11 system

[alikob]

Hello,

I am trying to see if the following design criteria, make sense for saving battery life in small BLE dongle using a coin battery like C2032. I am using nrf51822, with SDK11, having a HID,Batt, and some custom services, in addition having a beacon and scanner. Here is the design idea: to start my firmware by turning on scanner only and looking for specific beacon signature, which is provided by any iPhone, as soon as I see the signature, I will turn on everything, such as Beacon transmitter and HID service advertisement.  This way, my dongle is idling in scanner mode only for ever until it sees a beacon signal. Also in case of missing beacon signal, it goes into scanner mode again, to save battery life. Is this make sense, or I am missing something here? Thanks for any advice or clue!

[FormerMember]

RX mode in the RADIO (scanner mode) is the mode that consumes the most power, see the product specification chapter 8.5.2. It would therefore be a good idea to have scan window that is shorter than the scan interval, to save some power.  

In addition, could it be an option to look at the nRF52810, it uses less current in RX mode than the nRF51822.

[alikob]

Hi Kristin, I am going by default value of scanner_beacon.c file example in SDK11 which is:

#define SCAN_INTERVAL_MS  100
#define WINDOW_LEN_MS    (SCAN_INTERVAL_MS / 4)

I hope that's OK, I also tried turning on beacon and advertising signal, after receiving 
central beacon signal in scanner_evt_handler, it seems its working OK. Thanks for reply. 

[FormerMember]

For the scan interval value, I would recommend you to check if it works ok, and also check if Apples bluetooth developer guide has to some suggested scan interval values (since the scanner is mostly looking for iPhones(?)).