Direct Advertisement, how to setup central?

[FI]

Hello,

I have a peripheral based on the nrf52 that connects to my Android phone already in direct advertisement mode.

I am trying to get a NRF52 central working with this direct advertisement. Normal advertisement modes works.

What is the key steps that is needed to have the central setup correctly?

Thanks in advance!

FI

[FormerMember]

When using direct advertising, there is no specific setup for the central, except that you have to make sure that the central is scanning with appropriate scan interval/scan window.

In order to achieve a fast connection establishment a possible, the central should have close to continuous scanning and have a fairly short scan interval. Bluetooth core specification v.4.2, vol. 3, part C, appendix A recommends the following parameters for a fast connection initiation:

• Scan interval: 30 ms to 60 ms
• Scan window: 30 ms
• Minimum time for doing the scanning (scan period): 30.72 s.

[FI]

Kristin, Thanks for your input.

I should clarify better, the implementation:

1. Only DIRECT ADVERTISEMENT SLOW is enabled on peripheral, low duty cycle, but the timeout is very very long.

2. Scan window and interval changed to your 30ms/60ms on central per your advise.

3. Scan params setup: no scan request, no whitelist

4. No device manager implemented in the Central.

For normal advertisement the central connects to peripheral fine. Only when the peripheral switch to DIRECT ADV SLOW after an intended link dropout, the central fails to establish the connection.

When using an Android phone as a central using the Nordic master control panel, the above proposed use scenario works fine.

What else I should look into? I have read about the ADDR type being Public or Random, but was not able to find where to specify that either in the Central app nor the Peripheral.

Thanks again!

FI