CIRCUIT FOR SYNCHRONOUSLY EXCHANGING DATA IN BOTH DIRECTIONS AND SCAN TESTING METHOD THEREOF

摘要

PURPOSE: A synchronizing circuit is provided which is inserted nearby the center of a bus between driving entities so that data in both directions which move in the opposite directions on the bus are 'swapped' in the same clock cycle and do not collide each other. CONSTITUTION: At least, one swapper circuit (105) is electrically connected between entities (115 and 116) which share buses (103 and 110). This swapper includes pairs (106 and 107, and 108 and 109) of series-connection latches and tri-state circuits which are each connected in parallel to each data direction. This swapper operates as a rotary door, fetches data moving from one side of the bus, and moves the data to the other side without any collision. The respective driving entities are provided with master/slave latches (102 and 104, and 114 and 111) equipped with scan-in/scan-out ports to permit a test of the internal node of the circuit.