Design Of High-speed 8-bit RISC MCU Core

Nowadays, Micro-Controllers (MCUs) have been widely used in many fields, and among them the 8-bit MCU has the widest use. With the extending and development of MCUs' applications in fields of industrial control, electronic equipments, military meters, information applications and many kinds of intellective equipments, the typical 8-bit MCU represented by MCS-51 emerges some limitations, such as low frequency and low working efficiency. To overcome these handicaps, a new type of 8-bit MCU core suitable for embedded applications has been introduced in this thesis.In order to find out the critical factors that limit the performance of the typical 8-bit MCU, a systematical analysis of MCS-51 has been carried out in this thesis. It has been found that the major limitations of typical 8-bit MCU are the ALU structure based on accumulator and the CISC architecture adopted in MCS-51 design. Then a Top-Down design of 8-bit RISC micro-controller is presented to overcome the limitations of the MCS-51 MCU. The core is based on Harvard architecture with 16-bit instruction length and 8-bit data length. The performance of MCU has been improved greatly by introducing single-clock-cycle instructions, setting multiple high-speed working registers and replacing micro-program with direct logic block etc.To keep the MCU core reusable and transplantable, the whole MCU core has been coded for synthesis in Verilog HDL. It is shown from FPGA verification and computer simulation that the MCU core's maximum clock frequency and instruction efficiency are five times higher than those of MCS-51 chips.