Why the mouse report rate down after bonding??

Question

Hi all, 
 I used the ble_app_hids_mouse example in SDK 4.4.1 and found:
1.when the mouse does the first bonding with the master, the report rate could reach 125Hz(I set one timer with 8ms interrupt interval to toggle the mouse_key_send());
2.re-start the mouse by power on, the report rate could not run at 125Hz, instead of 100Hz, and I used a pin to toggle the interval of mouse_key_send(), its period still keeps at 8ms once.
And the interval between two continuous packets sent from mouse to master, scoped by the Sniffer, is about 10ms which meets the 100Hz.
It seems that only 125Hz could happen in the first bonding.
It's so strange, and something different between first bonding and restart?
 
 Thanks.

Håkon Alseth · Accepted Answer

Hi. 
 Initially, the slave and master will connect with a low connection interval in order to make the bonding/discovery procedure go fast. After a given period, you will negotiate updated connection parameters (usually set by "FIRST_CONN_PARAMS_UPDATE_DELAY" define on the slave side) 
 The connection interval given from the master must then be between your minimum and maximum connection interval (defines MIN_CONN_INTERVAL and MAX_CONN_INTERVAL). If the master does not give you a interval between min and max, the slave will disconnect the link. 
 In order to scale the mouse properly according to your connection interval, you should then use "radio notification" library to send mouse-sensor-data. 
 Best regards
Håkon