In an embodiment, a system has a bus interface port, a selection circuit coupled to the bus interface port, a first bus interface circuit coupled to the selection circuit and a second bus interface circuit coupled to the selection circuit. The selection circuit is configured to select between the first bus interface circuit and the second bus interface circuit. The system also has an initialization circuit configured to detect a first codeword written to the bus interface port, and activate the second bus interface circuit if the first codeword is detected.