ECE 3544 Project 5 – Datapath and Finite State Machine Design Solution

Project 5 – Datapath and Finite State Machine Design

Read this specification in its entirety before you begin working on the project!
Read the Assignment page on Canvas where you downloaded the project materials!

You must do this assignment individually. The following represent unauthorized aids, as the term is used to define cheating in the Virginia Tech Honor System Constitution:
• Using any design element – including Verilog code – from any printed or electronic source other than your course textbook and those sources posted on the course Canvas site.



Project Objective
In this project, you will design and implement a datapath, along with a finite state machine to model the controller for the datapath. The core of the FSMD will center on two interacting state machines: one to supply values from the inputs to the operand registers and datapath, and one to perform operations. While most of the instructions can be structured as micro-operations, the FSMD will contain a multiply instruction that it will perform over multiple cycles.

Requirements
The DE1-SoC board IS REQUIRED for this project. You must have the current versions of ModelSim ALTERA

Datapath Operations

Operation Result of the Operation Operation code
AND Your ID[T] Bitwise-AND the value {A, B} with the last four digits of your student number, expressed in BCD. 0000
Add[A] Add A and B. Take A and B as 8-bit signed 2’s complement operands, sign-extended to 16 bits. 0001



The Operation table continues on the next page.
Subtract[A] Subtract B from A. Take A and B as 8-bit signed 2’s complement operands, sign-extended to 16 bits. 0010
Negate[A] Take the 2’s complement of A. Take A as an 8-bit signed 2’s complement operand, sign-extended to 16 bits. 0011
NAND[B] Bitwise-NAND the values of A and B. 0100
NOR[B] Bitwise-NOR the values of A and B. 0101
XOR[B] Bitwise-XOR the values of A and B. 0110
(1’s) Complement[B] Bitwise-complement the value of A. 0111
Circular Shift Right[CS] Rotate A to the right by B positions. Take B as a 4-bit unsigned operand. 1001
Circular Shift Left[CS] Rotate A to the left by B positions. Take B as a 4-bit unsigned operand. 1000
Arithmetic Shift Right[AS] Arithmetically shift A to the right by B positions. Take B as a 4-bit unsigned operand. 1011
Arithmetic Shift Left[AS] Arithmetically shift A to the left by B positions. Take B as a 4-bit unsigned operand. 1010
Multiply[M] Multiply A and B. Take A as the multiplicand, and B as the multiplier. 1100

Notes
[T] Suppose that your student ID ends with the digits 1854. For A = 11101010 and B = 01000011, the result of this operation would be (1854)16 AND (EA43)16 = (0840)16.
[A] For arithmetic operations, the 16-bit result should reflect an operation performed upon 16-bit signextended versions of operands A and B.
[B] For bitwise operations, the result is an 8-bit value zero-filled to 16-bits.
[CS] For circular shift operations, you are rotating an 8-bit value (A) through a 16-bit register. Imagine that operand A is zero-filled to 16 bits before being rotated.
[AS] For arithmetic shift operations, operand A represents a signed 2’s complement value. The result should reflect a 16-bit sign-extended version of operand A shifted by a number of positions equal to the value of operand B.
[M] For the multiply operation, A and B are unsigned values. The 16-bit result represents an unsigned value.
[D] For any debug operations, the operation codes are to be defined by you as part of your design.

Do not use the Arithmetic Shift, multiply, division, or modulus dataflow operators to implement any of your operations.

System Interface
The system has the following inputs:
• Clock / CLOCK_50 – The DE1-SoC board has four 50 MHz clock signals. Use CLOCK_50 as the clock for the sequential elements of your design. Do not use the switches or pushbuttons as clock signals.
• Reset / KEY[0] – The Reset button is an active-low system reset. Pressing and releasing the Reset button should return the system to its initial state.
• Enter / KEY[1] – The Enter button is used to enter values from the Switches as described in the Method of Operation, and to advance the multiplication operation to its next partial product.
• Switches / SW[7:0] – The system uses the Switches to provide operand values. Operation codes are 4-bit values that use SW[3:0]. In general, A and B are 8-bit values, but in cases where B is a 4-bit value, it should use SW[3:0].

The system has the following outputs:
• Hex Displays / HEX[3:0]: For regular operations, the hex displays should show the current value of the result register in hexadecimal. HEX[0] is the least significant digit. Regular operations should use all four displays to show a 16-bit result, with leading zeroes as needed. The result should appear as a 16-bit signed 2’s complement value as needed. For example, (-1)10 = (FFFF)16. For debug operations, provide documentation in your report that describes the significance of each displayed value and the way the value is displayed.

For all operations except the multiply operations, the result should be display “immediately” after all operands have been entered. Implement the multiply operation using the method for serial multiplication described in the lecture slides. Each time the user presses and releases Enter, the result should show the value of the product register after the shift.



Switches SW[9:8] are available as optional inputs for you to use in debugging your design. LEDs LED[9:0] and hex displays HEX[5:4] are available as debugging outputs. If you choose to use these inputs and outputs for debugging, document your methodology for using them in your project report. If you choose not to use the optional outputs, they should be turned off.

Method of Operation
After being reset, the system should wait for an operation. To enter an operation, set the Switches to an operation code, then press and release Enter. To enter operand A, set the Switches to the value of A, then press and release Enter. For operations that use operand B, set the switches to the value of B, then press and release Enter.

For all operations except for the multiply operations, the result should be displayed as soon as the last operand has been entered. For example, the result of the addition operation should be displayed as soon as Enter is released when entering B.

For the multiply operation, after multiplier B is entered, the user must press and release Enter eight more times – once for each step in generating the product. After B is entered, the result should display the value of the product register with its initial value. Since we have eight-bit operands, the register must be shifted eight times.
For each of the next eight presses of Enter, the result should display the product register after shift is performed.

After each operation is completed, the system should go back to waiting for an operation. Between operations, the seven segment displays should display the result of the operation that was just completed. Changing the switches should not affect the value displayed by the seven segment displays.

For your debug operations, you should consider internal values of your design to display on the LEDS and HEX5/HEX4 displays. You should briefly describe any design decisions you made about the debug operations in your report.

In summary, the steps for operating the device are:

0. Between operations, the system is waiting for the user to enter an operation code.
1. Set SW[3:0] to the desired operation code. Press and release Enter.
2. Set SW[7:0] to the value of operand A. Press and release Enter. For operations requiring only operand A, go to Step 4.
3. For operations requiring operand B, set SW[7:0] to the value of operand B. Press and release Enter.
4. For all operations except the multiply operation, HEX[3:0] should now display the result. Return to Step 0. For the multiply operation, the displays should now show {8’b0, B}. This is the initial value of the product register in the multiplier described in the lecture notes. Continue to Step 5.
5. For the multiply operation, press and release Enter eight more times to show the result. After each press and release, HEX[3:0] should show the value the product register after the shift step. After the eighth press, HEX[3:0] should display the result of the multiply operation. Return to Step 0.

Design Tips
• Before writing any modules, work several examples by hand for each operation to make sure you understand how they should work.
• Design smaller aspects of this system individually. Implement and test them before moving on to the next aspect. You will be more successful taking this approach, as opposed to trying to implement the whole system before testing any of it.
• Break the design into communicating finite state machines, e.g., a state machine for the multiply operations and another for entering operation codes and operands.
• Test each of your components in simulation using a test bench before trying them on the DE0 Nano.

Project Submission
Write a report describing your design and implementation process.
• Discuss the decisions you made about implementing the elements of your design.
• Include a detailed block diagram of the interacting units in your system.
• Include a state diagram for the system controller, and the state diagrams of other units that might require them.
• Include waveforms showing the correct behavior of your design. Provide a waveform for each of the operations.
• Document any additions you make for debugging purposes and describe your motivation for each debug operation.


Your project submission on Canvas should include the following items:
1. Project report in Word or PDF.
2. A Quartus Archive containing the source files for your top-level module, any modules that the top-level module requires to function, and your test benches for the top-level module. To create the Quartus Archive, choose Project > Archive Project after you complete your implementation. When prompted for a name for your archive, the default archive name will be the same as the original archive. Append your Virginia Tech PID to the end of the filename. Make certain that you submit the archive that you create – the one containing your solution to the project – and not the one that I provided to you – the one that only contains the initial files.


Grading for your submission will be as described on the cover sheet included with this description.