Apparatus and method for configurable use of groups of pads of a system on chip

Abstract

An integrated circuit chip has pads that are grouped into a number of groups, and also has functional modules that share, among each other, use of two or more groups of the pads (also called “external function” groups), for transferring signals (such as data signals and control signals) to or from external circuitry. Each functional module has one or more groups of terminals (also called “internal function” groups) for carrying these signals. The number I of internal functional groups is greater than another number E of external function groups. Therefore, at any given time, a number I-E internal function groups are uncoupled (i.e. not coupled to any pads of the integrated circuit chip). Couplings among groups are implemented independent of each other in a crossbar switch having I internal ports and E external ports, and at least I-E internal ports are always uncoupled. Each internal port is hardwired to an internal function group, and each external port is hardwired to an external function group. During normal operation, the crossbar switch temporarily couples one or more external ports to a corresponding number of internal ports. The temporary couplings inside the crossbar switch may be changed only on power-up, or may be changed at any time during operation. A configuration circuit indicates to the crossbar switch the to-be-made couplings. The configuration circuit may also supply disable signals and enable signals to various functional modules, and/or the external circuits, if couplings therebetween can be changed during operation.