BLE Advertisment Interval Minimum Size

[FormerMember]

In ble_gap.h I noticed a parameter called BLE_GAP_ADV_INTERVAL_MIN, which determines the minimum gap between BLE advertisements. Current setting is 0x0020.

Currently in AdvertiserInitializer.h, the CONNECTABLE_ADV_INTERVAL is set to 0x0020. With my currently application, the average time between advertisements is 28uS, which is measured at the receivers end.

I have two questions.

1 What is the smallest possible interval between BLE advertisments?

I'm guessing this is dependent on the message length and settings. So I think a more appropriate question

2. Is there a simple formula, which could be used to get a reasonable estimate for different message lengths and settings.

My current approach is simply to experiment with different message lengths and settings and to record the average time between messages at the receiver end.

[Petter Myhre]

The smallest possible advertising interval is 20ms, this is defined by Bluetooth Core Specification 4.1, Volume 3, Part C, Section 7.8.5.

In BLE there are three advertising channels, and one advertising packet is sent on each of these in each interval.