Implementation of Control Unit for Microprocessor Trainer (Data Transfer and Program Control Instructions)

Abstract

The main objective of this paper is to implement a control unit for the 16 bit CPU used in Microprocessor Trainer. In Microprocessor Trainer, there are six modules and they are connected by the address bus (A [0...15]), the data bus (D [0...15]) and the control buses (MEMWR, MEMRD, IOWR and IORD). The modules involved in Microprocessor Trainer are CPU module, DMA module, Memory module, I/OCPU module, I/O Interface module and power supply. The Microprocessor Trainer uses 16- bit wide instruction sets. The whole module is supplied +5V DC from the power supply. The control unit is responsible for instruction fetching, decoding, executing, generating control signals such as MEMWR, MEMRD, IOWR, IORD etc. Control unit of this paper consists of following data transfer and program control instructions: Move, Store Word, Load Word, Load Halfword, Branch on equal, Branch on not equal, Branch on zero, Branch on not zero, Branch Greater than, Branch Less than, Jump, Call, Return, In, Out and Halt. All operations are controlled by using PIC 18F452 microcontroller. The control microprogram is developed with assembly language to control the operation precisely and to minimize the clock cycle