BLE APP TIMER

[wu]

hi,

Our customer find BLE's app_timer emerge a deviation when use the BLE's app_timer. the customer is developing bracelet product , their programs with two app_timer, the one app_ timer generating 1 second timing for date and time information.another use in pedometer function.the app_timer wake up every 25ms when counting Steps,and it wake up every minute when not used in counting Steps. if Bracelet put on the table,or rarely walk. Calendar time is right, but the Calendar time will be faster when counting Steps frequently, it will be faster two or three minutes a day. However, it not emerge a deviation under s110 v6.0 SDK v5.2 and the same program , what is the reason?

Thanks and Best regards

[Susheel Nuguru]

Hi, We need more information to analyse this.

1. what kind of intervals (if in connection or advertising) is the device using?

2. when not counting steps, is the device still in connection/advertising? if not is it in sleep mode?

3. the difference in app timer events when counting steps and when not countin steps is 40 times(1000ms/25ms). You say when counting steps the calender is faster by three minutes a day (which uses 25ms timer). Are you sure that when not counting steps (using app timer of 1 sec) the app_timer is still faster by 9 seconds (three minutes/40 = 180/40 = 9). If this is true then both of the deviations are atleast consistent.

[guozhong.chen]

1. what kind of intervals (if in connection or advertising) is the device using?
   Is usually not connected, but the advertising

2. when not counting steps, is the device still in connection/advertising? if not is it in sleep mode? advertising or connection is possible, if it is connected APP. Program calls the following function into Sleep.

   uint8_t PowerSave(void) { uint8_t mSdIsEnabled; sd_softdevice_is_enabled(&mSdIsEnabled);

    if(mSdIsEnabled)
    {
        uint32_t err_code;
        //TRACE1("$");
        err_code = sd_app_evt_wait();
        APP_ERROR_CHECK(err_code);  
   }
   else
   {
        NRF_POWER->TASKS_LOWPWR = 1;
        __WFE();
   
        __SEV();
        __WFE();  
   }
   return mSdIsEnabled;
   

   }

3. the difference in app timer events when counting steps and when not countin steps is 40 times(1000ms/25ms). You say when counting steps the calender is faster by three minutes a day (which uses 25ms timer). Are you sure that when not counting steps (using app timer of 1 sec) the app_timer is still faster by 9 seconds (three minutes/40 = 180/40 = 9). If this is true then both of the deviations are atleast consistent.

From Friday to now, almost pedometer and computer time