Abstract
This paper presents the design of high speed processor for a sequence logic control using field programmable gate array(FPGA). The sequence logic controller is widely used for automating a variety of industrial plants. The FPGA designed by VHDL consists of program and data memory interface block, input and output block, instruction fetch and decoder block, register and ALU block, program counter block, debug control block respectively. Dedicated clock inputs in the FPGA were used for high speed execution, and also the program memory was separated from the data memory for high speed execution of the sequence instructions at 40 MHz clock. Therefore it was possible that sequence instructions could be operated at the same time during the instruction fetch cycle. In order to reduce the instruction decoding time and the interface time of the data memory interface, an instruction code size was implemented by 16 bits or 32 bits respectively. And the real time debug operation was implemented for easy debugging the designed processor. This FPGA was synthesized by pASIC 2 SpDE and Synplify-Lite synthesis tool of Quick Logic company. The final simulation for worst cases was successfully performed under a Verilog HDL simulation environment. And the FPGA programmed for an 84 pin PLCC package was applied to sequence control system with inputs and outputs of 256 points. The designed processor for the sequence logic was compared with the control system using the DSP(TM320C32-40MHz) and conventional PLC system. The designed processor for the sequence logic showed good performance.
