We're developing an app using iOS's low energy bluetooth stack. The app connects with a peripheral device to periodically read data. All's great except for a persistent, yet random, immediate peripheral timeout on re-connect. This is the error detail from CBCentralManager at didDisconnectPeripheral.
> Domain=CBErrorDomain > Code=6 > NSLocalizedDescription=The connection has timed out unexpectedly
Each disconnect happens as soon as we call discoverServices on the newly connected peripheral (which has [peripheral isConnected] == YES). When looking at the peripheral's logs, it shows it is not receiving a connection request from iOS over bluetooth. When placed in a bluetooth isolation chamber, our bluetooth sniffer sees no bluetooth connection request packets for these timed-out connections…implying that CBCentralManager is replying in didConnectPeripheral with a peripheral that cannot really be connected.
We've written a test harness to reliably reproduce this issue. The harness establishes a connection, transmits/receives some data, explicitly writes a characteristic to have the peripheral terminate the connection, then attempts to reconnect. For every 100 connect-then-reconnects, an average 10 of these will experience a peripheral timeout on re-connect. After 2-3 timeout on re-connect attempts, a lasting connection is established and the harness proceeds with its cycling.
Here are the steps followed by the test harness:
1. Scan for a peripheral. 2. Stop scan 3. Call [CBCentralManager connectPeripheral] 4. CBCentralManager replies on didConnectPeripheral. 5. Call discoverServices on peripheral 6. Read/write data to/from peripheral 7. Explicitly disconnect peripheral by writing a characteristic 8. CBCentralManager replies on didDisconnectPeripheral > CBErrorDomain Code=7 > The specified device has disconnected from us 9. Perform a reconnect by returning to step 1
Roughly 10% of the time when we perform the reconnect in step 9, we see the below happen 2-3 times before a successful reconnect
1-5 as above 6. CBCentralManager replies on didDisconnectPeripheral > Domain=CBErrorDomain > Code=6 > NSLocalizedDescription=The connection has timed out unexpectedly 7. Perform a reconnect by returning to step 1
Any guidance would be greatly appreciated.
Thank you,
Anthony |