Inter-chip communication system

Abstract

The complexity of user designs, the limited capacity of FPGA chips, and the limited number of chip pinouts have resulted in the development of inter-chip communication technology that necessitates the transfer of a large amount of data across a limited number of pins in the shortest amount of time. The inter-chip communication system transfers signals across FPGA chip boundaries only when these signals change values. Thus, no cycles are wasted and every event signal has a fair chance of achieving communication across chip boundaries. The inter-chip communication system includes a series of event detectors that detect changes in signal values and packet schedulers which can then schedule the transfer of these changed signal values to another designated chip. Working with a plurality of signal groups that represents signals at the separated connections, the event detector detects events (or changes in signal values). When an event has been detected, the event detector alerts the packet scheduler. The packet scheduler employs a token ring scheme as follows. When the packet scheduler receives a token and detects an event, the packet scheduler 'grabs' the token and schedules the transmission of this packet in the next packet cycle. If, however, the packet scheduler receives the token but does not detect an event, it will pass the token to the next packet scheduler. At the end of each packet cycle, the packet scheduler that grabbed the token will pass the token to the next logic associated with another packet.