Scan all peripheral(advertising) devices

[Aswati Vijaykumar]

Hi Nordic Team,

Please suggest logic to scan all peripheral devices by the central device.

In my BLE project when I'm trying to scan all peripheral devices which are advertising few of them are not getting scanned, please provide some solution to resolve this. 

Please help as soon as possible. 

[Einar Thorsrud]

Hi,

There is generally no way to guarantee that you have received advertisement packets from all devices, but the longer time you scan for the more likely it is that you will receive advertising packets for all devices within range. The main factors that affect this are:

• The scan duty cycle (a combination of advertising interval and advertising window size)
• The number of advertising devices in range
  • If there are a large number of advertisers, the collisions increase.
    • If there are collisions between packets with similar RSSI, both packets will likely be lost.
    • If there is a collision between packets of different RSSI, the strongest packet may still be received correctly.
• In any case, the longer you can, the better the probability of receiving packets from all devices.

Is there anything particular with the devices you do not pick up? What is the difference between those and the other devices? And are you sure you are not filtering them out in SW somehow?