Answer
The Master is the device that initiates the connection as per the classic BT inquiry and paging process. There is no option to configure Master/Slave roles in smartBASIC. However, if the BT900 initiates the connection using the BtcSppConnect(BTA$) command then it can be assumed that it has taken the Master role. The BT900 will have performed the inquiry/page, and the remote device will have performed the inquiry/page scan.