Receving advertisement packets in scanner problem

[mani]

Hi Team,

                Iam doing project called automation of light using BLE technology.

Here Iam using sdk 12.1.0(ble_app_hrs_c) example for scanning or receiving and i flashed the ble_app_hrs_c example in nRF51822 Dk.This nRF51822Dk acting as receiver. I have nrf51822 beacons ,this beacons acting as transmitter.My beacons can advertise every 1000ms and connection interval 500ms.Till now my project is working fine. my question is

1->When i come with multiple beacons(let us consider 4 beacons) near to receiver or scanner ,does (ble_app_hrs_c) example receives all the advertisement packets from all 4 beacons at regular interval of time. 2->Is there any missing of packets at receiver end?? 3->how can i receive all the advertisement packets in scanner ,do i need to change the scanning interval or connecting,non connecting modes ??

[Sigurd]

Yes, the ble_app_multilink_central will continue to scan for advertising packets, even when connected to other peripherals. When only doing advertisement, there is a small chance that an advertisement packet is lost, since the central might be scanning on a different advertising channel when the packet is sent. So if you need that no packets are dropped, you will need to connect with your "beacons" to the central.

In a connection, Bluetooth low energy uses CRC and the packet contains a sequence number and next expected sequence number to ack/nack a packet. Every packet will be acknowledged at the link layer, so if there isn't an acknowledgement, the packet will be retransmitted.

[Sigurd]

1. Yes, by default the ble_app_multilink_central example will try to connect to all peripherals that are named "Nordic_Blinky". (it will look for the name in the on_adv_report() function). It will continue to scan and connect until it have connected to the number of peripherals defined by CENTRAL_LINK_COUNT. By default this is set to 8, but can be increased to 20. The CENTRAL_LINK_COUNT is the number of central links used by the application. When changing this number remember to adjust the RAM settings

2. Yes, the central will scan on all 3 advertising channels (37,39 and 39). When you send an advertising packet from the peripheral, the peripheral will actually send the packet on all 3 advertising channels. It will first send it on channel 37, then on 38 and then on 39.