Accessory control interface

These teachings relate generally to electronic devices, such as mobile terminals, including cellular telephones and personal communicators, and to accessory units for mobile terminals, and more specifically to mobile terminal/accessory interface hardware and software. Disclosed is an interface () between a master device () and a slave device (). The interface includes a bit serial bidirectional signal line (A) for conveying commands and associated data from the master device to the slave device, and for conveying a reset signal, an interrupt signal, and a learning sequence signal for specifying a duration of a bit time for data transferred from the slave device to the master device. The bit serial bidirectional signal line further indicates an accessory device connected/disconnected state to the master device.