With TI BLE version 1.3.1 on CC2541 as peripheral (slave), using iOS 6.1.x as a Central (master), we've seen sporadic drops of the connection after updating the connection parameters with LL_CONNECTION_UPDATE_REQ. It doesn't always happen, but it does seem to be related to the update request.
One thing we have consistently observed is that there are only 5 connection events between sending LL_CONNECTION_UPDATE_REQ and an actual parameter change. The spec says there should be at least 6 events (Vol 6, section 5.1.1
Connection Update Procedure:
The Instant field of the LL_CONNECTION_UPDATE_REQ PDU shall be used
to indicate the connEventCount when the updated parameters shall be applied;
this is known as the instant. The master should allow a minimum of 6 connection
events that the slave will be listening for before the instant occurs.
Could this "early instant" cause a problem for the TI stack? I've seen the peripheral respond ONCE to the first packet with new timings, and then never again.
