Crossbar switch with input/output buffers having multiplexed control

Abstract

An electronic crossbar switch employs a switch array for selectively routing signals between its terminals. A separate port provided for each terminal buffers signals flowing in and out of the switch. Each port can be configured to operate with or without tristate buffering under control of a tristate control signal, to optionally latch input or output signals in response to clock and clock enable signals, and to buffer signals passing in or out of the switch terminal in response to a direction control signal. A set of control inputs are provided in common to all ports, allowing an external host to transmit control signals in parallel to each port. Each port may be programmed to select any of its control inputs as its tristate, clock enable, clocking or direction control signal. A parallel 'key' bus is also provided in common to all ports for conveying a key address from the host controller. Each port stores an internal port address and when the key address matches the port address, the port asserts an internal 'KEY' signal. Each port may be configured to use the KEY signal selectively as either its tristate, clock enable, clock or direction control signal.