Development Of 6502MCU In-Circuit Emulator

In-Circuit Emulator is one of the most important component parts of Microcomputer Development Systems. It is a powerful tool to develop microcontroller. The 6502MCU In-Circuit Emulator (ICE) in this paper is specifically designed for the 6502 series microcontroller (MCU) which developed by Casue Technology Co.,Ltd. This MCU has a 6502 compatible CPU core, is mostly used in the household electrical appliances and portable electronic products. It is very importance for the application and development of 6502 series MCU to develop 6502MCU ICE.In this paper, the entire process of research and design of the 6502MCU ICE are described in detail. The 6502MCU ICE has many basic functions which are realized by FPGA device, such as download, breakpoint, single-step, run, trace, registers and I/O operating, and so on. It has a simple hardware structure and low cost, can be used as a potent tool to apply and develop 6502MCU. According to practical need, we can easily update ICE. The Microcomputer Development System and ICE are introduced comprehensively at the beginning of this paper. After that, we build a design scheme on the base of internal architecture and timing of 6502MCU and finished the hardware design. At the same time, we especially explained how to realize each functions of ICE and elements of control logic, and depend on it we completed control logic design. The control logic is also simulated and tested at register transfer level. The communication between ICE and computer adopt asynchronous serial communication mode through RS-232 port. Based on communication protocols and combine with basic functions of ICE, we design the serial communication program and give a particular description of the serial communication program by flow chart. Finally, test circuit and program of ICE are introduced and test methods of each functions are also gave. Test results of 6502MCU ICE demonstrate that the design scheme put forward in this paper is feasible.