Patent attributes
System, methods, and apparatus are described that facilitate signaling between devices over a single bi-directional line. In an example, the apparatus couples a first device to a second device via a single bi-directional line, indicates initiation of a first action, initiated at the first device, by sending a first single transition on the single bi-directional line from the first device to the second device, and indicates initiation of a second action, initiated at the second device, by sending a second single transition on the single bi-directional line from the second device to the first device. In another example, a first device initiates a first action, indicates initiation of the first action by generating a first event on a single bi-directional line, and receives an indication of a second action initiated at a second device by observing a second event on the single bi-directional line.