4-Bit MCU VERILOG Softcore Design

For IC design corporations, a conversion of design methods from a traditional one to a hardware description language one would be imperative under the situation.Especially, they should establish their own IP-based integrating with practical project,innovate continually,increase the strength of exploiture, then they could base themselves upon this IC design which has become more and more dog-eat-dog.The research and practice to this paper would administer our company to build MCU softcore and extend our products based on it.As a traditional IC design company,lacking of technic foundation and abundant capital needed for advanced design methods, it's not easy for us to build our own design flow of softcore and complete product design. But we succeeded in it,Based on it,This MCU softcore have applied to serious of circuit design of infrared remote control transmit.This softcore has overpassed the FPGA validation,completed the sample exploitation of the infrared remote control transmit,overpassed the silicon validation,and it is placed in the stage of coming out a sample now.The team to establish own top-down design flow gradually, and developped the softcore in 8-bits MCU,also applying to the actual circuit design. The instruction system of this micro-controller design has 68 operational instructions.It is 4-bits MCU softcore and can complete the operations data deliver,the data operation, logic carries to calculate,judge the comparison and jump to turn, check the form with adjust to use the tiny operation in etc.It can provide the timer with two workings. In the whole design process,The MCU design specification had established first, defined the frame of the design, partition the sub-module, defined the registers.Then the instruction system have analyzed, designed the state machine that carry out the instructions. Afterwards, the Verilog coding design of the sequence state machine module,of the datapath module,of the bus controller module and of the timer moduel,etc had completed. And then I made it get across the absolute self-detection validation and FPGA validation. Finally, Finally The logic synthesis had completed and the physics synthesis implement. The software developer write the procedure of remote control,and made it the silicon validation.The key of this design is the design of instructions state machine.Every instruction cycle includes 8 machine clock cycles,is made up of fetch instruction, decoder instruction, execute instruction, writing RAM,writing register and reading RAM etc.When a 2-cycles or 3-cycles instruction is operated,operation state should be reserved until the operating data is executed. The whole work of the frame design,code design and verification of micro-controller have completed and applied it to the practical circuit design. This has become a milestone of top-down design flow in our company presently. After this,we exploited the more-bits CPU and finished the circuit design.Moreover,the scheduling of register and the state machine have designed.The scheduling design of multibyte multi-cycle instruction operation is also very pivotal, especially, the jumping instrucion operation and the jumping multibyte multi-cycle instruction operation should be designed as a key part.When completing the whole MCU coding design,the top-down design flow was fited for our company based on some general flow,combining design tools of same big design-tool company, according to the current characteristics of our company.Furthermore,the referrence specification of the coding style have constituted.