I have an nRF51822-based peripheral using the SoftDevice 110 v7.0.0 and SDK v6.0.0. The peripheral uses two custom characteristics under a single custom service. I'm using the Device Manager. The central is an Android app using the new Android L preview BLE stack.
About half the time the central attempts to connect to the GATT server, discover services, and bond, the connection is immediately dropped. Here's a Wireshark screenshot and log of when that happens.
screenshot_wireshark_reject.png
ll_reject_ind_2014-08-29.pcapng
And here are my security parameters:
// Timeout for Pairing Request or Security Request (in seconds).
#define SEC_PARAM_TIMEOUT 30
// Perform bonding.
#define SEC_PARAM_BOND 1
// Man In The Middle protection NOT required.
#define SEC_PARAM_MITM 0
// No I/O capabilities.
#define SEC_PARAM_IO_CAPABILITIES BLE_GAP_IO_CAPS_NONE
// Out Of Band data not available.
#define SEC_PARAM_OOB 0
// Minimum encryption key size.
#define SEC_PARAM_MIN_KEY_SIZE 7
// Maximum encryption key size.
#define SEC_PARAM_MAX_KEY_SIZE 16
I'd say this happens about a third to half the time. The rest of the time the connection is fine. Why is this happening? How do I debug this?
[Edit]
Here's the log from nRFLogger/MCP app on Android L:
