Increase BLE background scan window for faster re-connection

The scan window is increased from 11.25ms to 30ms.
The scan duty cycle is still very low at 2.34% while user experience
is greatly improved.
bug 16521059

Change-Id: Ice37c54fdc7d852fd19709112075e7492b6a1480

diff --git a/stack/include/btm_ble_api.h b/stack/include/btm_ble_api.h
index 956801e..9b0d60e 100644 (file)
--- a/stack/include/btm_ble_api.h
+++ b/stack/include/btm_ble_api.h
@@ -135,7 +135,7 @@ typedef UINT8   tBTM_BLE_SFP;
 #define BTM_BLE_SCAN_SLOW_INT_1    2048    /* 1.28 s   = 2048 *0.625 */
 #endif
 #ifndef BTM_BLE_SCAN_SLOW_WIN_1
-#define BTM_BLE_SCAN_SLOW_WIN_1   18      /* 11.25 ms = 18 *0.625 */
+#define BTM_BLE_SCAN_SLOW_WIN_1   48      /* 30 ms = 48 *0.625 */
 #endif
 
 /* default scan paramter used in reduced power cycle (background scanning) */