Description of FPGA components
Numerical control based on the FPGA components of a synchrone machine

FPGAs are VLSI (Very Large Scale Integration) components. They are user-programmable and essentially consist of three parts:

• a matrix of Configurable Logic Blocks (CLB) ;

• configurable input/output blocks ;

• a network of programmable interconnections.

Figure 1 shows the generic architecture of an FPGA.

There are several FPGA component manufacturers, including Actel, Xilinx and Altera (see [Doc. D 2 902]). These manufacturers use different technologies to build FPGAs. Among these technologies, those that enable FPGAs to be reprogrammed are the most interesting, as they offer great design flexibility. The most widely used reprogrammable FPGA technologies are :