Answer
In the upass sample, change the min and max value to the following: //Minimum acceptable connection interval (7.5ms) #define MIN_CONN_INTERVAL 7500 //Maximum acceptable connection interval (8 ms). #define MAX_CONN_INTERVAL 8000 If the central rejects the parameters: HandlerBleMsg event with BLE_EVBLEMSGID_CONN_PARMS_UPDATE_FAIL message ID will be trigged.