CODEWITHSUNDEEP
iphoneioscore-bluetoothbluetooth-lowenergy
chwi
chwi

Reputation: 2802

Bluetooth low energy connection interval on iPhone

The Apple Bluetooth Design Guidelines say that connection interval should be set as such on the peripheral

Interval Min ≥ 20 ms
Interval Min + 20 ms ≤ Interval Max

When setting min to 20 ms, max to 40 ms, I expect to get an acceptance from the iPhone and lowest available interval, but the iPhone always set 37.5 ms connection interval. Trying to push the max value down gives a rejected status from the iPhone, which then set the connection interval to ~100 ms.

Is it possible to get this down to 20 ms (since this is the minimum from Apple guidelines) in some way? What is the actual minimum? According to my observations, the Interval min can be set to 30 ms, without making any difference.

Upvotes: 3

Views: 5589

Answers (2)

kruzty
kruzty

Reputation: 21

I have been experimenting with this recently. This does not follow their guidelines so I'm not sure why it works, but using the following connection setting I was able to get an interval of 18.75 ms from an iPad:

  • min interval = 10 ms
  • max interval = 20 ms
  • latency = 0
  • timeout = 100 ms

Upvotes: 2

Jitender
Jitender

Reputation: 76

Bluetooth SIG defines connection interval min and max range values = 7.25msec to 4000msec. Implementation can choose any value in this range as connection interval min or max. However, the connection interval min shall not be greater than connection interval max. The minimum value depends on the battery considerations of the Peripheral and the maximum connection interval depends on the buffers available on the Peripheral. Iphone setting these values to 37.5 ms give us a hint that the buffers available on the Peripheral are constant. You can try to change this parameter and see if now you see the connection interval to be different.

Upvotes: 0

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