51822 connection intervals with Samsung Phones(S3, S4, note 2 on 4.3+)

[Li]

Dear All,

I've recently had a problem with interaction with samsung phones (S3, S4, note 2 on 4.3+) using 51822. The connection interval that I have is around 48ms with samsung version android. Our app required 20 ms as a minimal. After some tests, I believe, this is a pure samsung version android issue rather than hardware limits(I flash other ROMs (original android 4.3 from google) on those samsung phones and the connection interval reduces to 20ms and our app worked just fine. But I don't expect our users to flash their phones using third party ROMs.

I understand there have been other topics around this issue, but I don't seem to see any solutions for this problem? I've seen the last comments from the blow post, but don't know how to do that?

devzone.nordicsemi.com/.../

Any suggestions on how to overcome this problem is deeply appreciated (either on the phone side or on 51822 side)

L.

[Li]

Some add ons here.

I've tried to get the connection interval after the device is connected to the central. I've tested it on two different Android ROMs. One is original samsung android 4.3 on Note 2 and another one is a 3rd party ROM on S4.

The interesting thing that I observed is both have same connection interval (39). case BLE_GAP_EVT_CONNECTED: temp_value = p_ble_evt->evt.gap_evt.params.connected.conn_params.min_conn_interval;

However, on the phone side, the data rate is totally different. S4 on 3rd party ROM almost has doubled data rate than S3 on samsuing andorid 4.3

Any thoughts?

L.

[Li]

After some further diggings, the phenomena is clearer.

On S4, although the connection interval is 48.75ms, but in each connection, we are able to get two packets. However, on S3 and Note2, we are only getting ONE packet per connection.

Therefore, the question for now is, are we able to get how many packets are allowed to be exchanged between peripheral and central for each connection interval on 51822 side?