International Business Machines Corporation
DAISY-CHAINED SERIAL BUS FOR MULTIPLE SMALL FOOTPRINT DEVICES

Abstract:

An apparatus for data transfer includes a first node connected to a bus to communicate bidirectionally, and second nodes connected in series to the bus. Each second node lacks an internal clock and has fixed pads including a power, a ground, and signal pads to transfer a data frame, return data pads for a return signal, select pads for a selection signal and clock pads for a clock signal. Each second node is indexed by a hop count in the frame that is incremented each time the frame is transferred in topological order. Each second node is selectable using a mode defined by a combination of the hop count, a mask field and an address field in the frame. The signal pads are used for frame transfer in a selected mode controlled by a combination of the selection, clock and return signals.