May peripheral could auto connect to central

[zyj]

Hi all:

          Our usage scenario is to establish a connection and bonded between the NRF52840 peripheral device and the central device, and then restart the NRF52840 peripheral device at this time.  I hope that the NRF can actively connect with the newly connected central device.

   I found this this post ,but i am not sure ,Can I do IT  with 52840 ，52840 is a peripheral in my application ,and central is a smart phone. I want 52840 auto connect to smart phone after they have a connection before.

  Look forward to hearing from you

[Karl Ylvisaker]

Hello,

As awneil said, the decision to connect is entirely in the hands of the central, the peripheral will only advertise its presence and the possibility to connect with it. For a smartphone central, you would need to know how the smartphone is configured to handle automatic reconnections.
For this, you should check out Android/iOS specifications on how often their Bluetooth modules behave. For instance, Androids will by default only listen for and autoconnect to their previous connection, if I recall correctly.

Best regards,
Karl

[zyj]

but my sony earphone could connect to my smart phone after it power on ,and i want my NRF  do like this.

why sony earphone could auto connect and NRF can not?

[awneil]

But how that works is that the earphone advertises, the phone sees it, and it is the phone which automatically initiates the connection.

So you need to write your app to do that

[zyj]

get it ! thank you for your kind help!

[awneil]

You're welcome.

[Karl Ylvisaker]

Hello again,

zyj said:

why sony earphone could auto connect and NRF can not?

This has to do with the iOS/Android default Bluetooth adapter configuration. Typically, I would think they allow this for HID and/or Audio devices only.
So, if this is to work for your nRF, it depends on what your nRF device will be doing, as @awneil suggests.
For example, if you intend for your nRF to stream sensor data to your phone, then you will have to create a custom application on your phone that connects to your nRF device, and collects/processes the sensor data. Your phone will not do this automatically.

Be advised of the differentiation between Bluetooth Classic and Bluetooth Low-Energy handling when reading iOS/Android documentation. nRF devices supports Bluetooth Low-Energy only.

Best regards,
Karl