In bluetooth low energy, Can observer scan the peripheral device?

Question

I study the bluetooth low energy. During studying, I have a question.

As I know, possible data transaction Role is observer-broadcaster(connectionless) and central-peripheral(connection) in BLE. But, What I wonder is data transaction between observer and peripheral?? Is that possible?? In other words, Can observer scan the peripheral's broadcasting message?

If that is possible, Can central receive the broadcaster's advertising packet? and Can central scan the broadcaster's advertising packet?

Answer 1

An observer can scan the advertisements from the broadcaster, unless the advertiser (broadcaster)'s advertisements are of type nonconnectable.

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There are two types of scanning in Bluetooth Smart (Bluetooth Low Energy): passive and active.

Passive scanning just listens to advertisements (which contains advertisement data).

Active scanning when an advertisement is received it sends a scan request and the advertiser then sends a scan response (which contains scan response data) back.

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There are different types of advertisements in Bluetooth Smart:

• general advertisement: The typical advertisement whereto connections can be initiated. It supports active scanning.
• direct advertisement: The advertiser wants a particular device to connect to it instantly. It does not support active scanning and does not have any advertising data (except the connection addresses of both devices).
• discoverable advertisement: The advertiser supports active scanning, but can not be connected to. (i.e. broadcast of data).
• nonconnectable advertisement: The advertiser does not support active scanning, and can not be connected to. (i.e broadcast of data).