In GapAdv_enable function, check if the discoverable mode is set to "limited". If so, check that enableOptions = GAP_ADV_ENABLE_OPTIONS_USE_DURATION or GAP_ADV_ENABLE_OPTIONS_USE_MAX_EVENTS. 1. if enableOptions = GAP_ADV_ENABLE_OPTIONS_USE_DURATION: in this case durationOrMaxEvents param represents duration for advertising. therefore, we check that the given duration is no longer then 180 seconds. if its longer then 180s, we will return an error "bleInvalidRange". 2. if enableOptions = GAP_ADV_ENABLE_OPTIONS_USE_MAX_EVENTS: in this case durationOrMaxEvents param represents num of advertising events to perform. therefore, we need to calculate the duration of performing this number of adv events, with the given interval. also, we need to take advDelay into account (advDelay is set randomly in each adv event and its value is 0..10 [ms]). we will focus on the worst case when advDelay is 10ms. so the final value to compare will be: (interval + max_delay) * durationOrMaxEvents. if this value is longer the 180s, we will return an error "bleInvalidRange". Fixes related to Sysconfig: 1. added a checker which make sure the advertising flags given by the user are legal (for example General & Limited can't be set together, according to the spec. 2. added some comments which guide the user about how to use the parameters that are passed to gap_advenable function when using Limited Discoverable Mode.