In this project, the students will implement a pipeline CPU using the Xilinx design package for FPGAs. You can use any information available in previous labs if needed.

1. Pipelining

As described in lab 4

2. Circuits of the Instruction Fetch Stage

As described in lab 4

3. Circuits of the Instruction Decode Stage

As described in lab 4

4. Circuits of the Execution Stage

As described in lab 5

5. Circuits of the Memory Access Stage

As described in lab 5

6. Circuits of the Write Back Stage

As described in lab 6

In order to focus our attention on the WB stage easily, the baseline CPU shown in Figure 1 is redrawn by putting the register file on the WB stage where the execution result of an instruction is written as shown in Figure 2. The state of the art content can be read correctly in the ID stage after it is written at the end of its WB stage. Data hazards occur in the code example shown in Figure 3. One solution that you need to do is to force these instructions to wait until the register $3 is updated by the first instruction. This waiting is called a pipeline stall

Figure 1 Pipeline write back (WB) stage

Figure 2 Writing result to the register file in the write back stage

Figure 3 Data hazard examples

7. Table 1 lists the names and usages of the 32 registers in the register file.

Table 1 MIPS general purpose register

8. Table 2 lists some MIPS instructions that will be implemented in our CPU

Table 2 MIPS integration instruction

9. Initialize the first 10 words of the register (Regfile block) with the following HEX values:

00000000

A00000AA

10000011

20000022

30000033

40000044

50000055

60000066

70000077

80000088

90000099

10. Write a Verilog code that implement the following instructions using the design shown in Figure 3. Write a Verilog test bench to verify your code: (You have to show qa and qb signals that output from the Regfile block in your simulation outputs)

11. Write a report that contains the following:
    1. Your Verilog design code. Use:
    2. Device: Zyboboard (XC7Z010- -1CLG400C)
    3. Your Verilog Test Bench design code. Add `timescale 1ns/1ps as the first line of your test bench file.
    4. The waveforms resulting from the verification of your design with ModelSim showing all the signals written in and out from the MEM/WB register and the inputs to the Regfile block.
    5. The design schematics from the Xilinx synthesis of your design. Do not use any area constraints. Snapshot of the I/O Planning and
    6. Snapshot of the floor planning
    7. Generate the bitstream.
    8. The design should be free from errors when synthesized, implemented and generated of bit stream.
    9. Connect the board and power it ON. Open a hardware session, and program the FPGA. Make sure that the micro-USB cable is connected to the JTAG PROG connector (next to the power supply connector). Make sure that the jumper on the board is set to select USB power.
    10. Select the Open Hardware Manager option and click OK.
    11. Click on the Open target link, then Auto Connect from the dropdown menu.
    12. The Hardware Session status changes from Unconnected to the server name and the device is highlighted. Also notice that the Status indicates that it is not programmed.
    13. Select the device in the Hardware Device Properties, and verify that the (.bit) file is selected as the programming file in the General tab.
    14. Choose sw0 of the logic slide switches (item number 9, page 38and 39, Week 8) as an input to control the beginning of fetching of the instructions.
    15. After finishing the last instruction, choose LED 0 of the logic LEDs (item number 8, page 38and 39, Week 8) to light on. You need to choose a signal as indicator that you finish your code.
    16. You need to take pictures of the ZyboBoard to show that the download is done without problems and to show the configurations described in items n and o. Failed to do that will result in 15 points deduction of your project grade.

12. REPORT FORMAT: Free form, but it must be:
    1. One report per group.
    2. Have a cover sheet with identification: Title, Class, Your Names, etc.
    3. You have to write an abstract at the beginning of the project report to describe what you are doing in the project.
    4. You should include an introduction for the project explaining with diagrams the connection between all the stages and what would be the benefit of using that architecture in the computer organization field.
    5. Use Microsoft word and your report should be uploaded in word format not PDF. If you know LaTex, you should upload the Tex file in addition to the PDF file.
    6. Single spaced

13. You have to upload the whole project design file zipped with the word file.