Implementation of FPGA technology as human-machine interface to Z80 microprocessor learning module

Microprocessor system is a must know subject in electrical engineering. Despite of learning through simulation, student, especially in polytechnic, have to be more involved in the hands on practice. Z80 is one of the simplest microprocessor system for studied. Many of existing Z80 learning board came with tons of user friendly interfaces, such as a keypad and alphanumerical LCD, however, the most important basic of this subject, the data transfer signaling, is sometime difficult to show. In this paper, we present a Z80 microprocessor module as learning facility with a HMI chip that is designed using FPGA chip, which is allow us to gate and control the microprocessor signals. The HMI chip implanted several control functions; the STEP unit, DMA unit, control memory unit, I/O control unit, address and data control unit, and system reset unit. Units in the HMI chip works very structured, and interconnected. With the signal controlled from the HMI chip units, the microprocessor work process becomes more easily to be manipulated and observed. The process of storing and reading program using DMA also can be easier to understand. Simple layout of the main board greatly facilitate student in operate and analyze a running program. Since the HMI chip built on an LVCMOS technology, while the classic Z80 CPU is still a CMOS, two-way bus logic level converters from 3.3V to 5V have to be used. Working frequency achieved is from 3MHz to 10MHz.