Team14 - Team Write-Up

Overview

We were asked to design a RISC-V CPU based on its ISA for our Instruction Architecture and Compilers course (IAC). It was an incredibly rewarding experience with great learning opportunities.

We were able to deliver in the span of three weeks:

• A Single Cycle CPU, see branch main
• A Pipelined 5-stages CPU, see branch proj-pipeline
• A 5-stages Pipelined CPU with direct-mapped cache, see branch proj-direct_cache
• A Single Cycle CPU with fully-associative cache, see branch proj-cache

Logic was also derived to implement a 4-way associative cache. System-Verilog draft of the code was submitted along this repository, but remains uncomplete. One could also check the Project directory to verify the individual .sv files and their respective testbenches.

Quick Start

exe.sh is a Shell script that loads different instructions and data into the processor.

exe.sh takes either zero, one or two arguments. These arguments precise the testbench used for the testing, whether it is the Formula Lights or Reference program:

Command	Outcome
source ./exe.sh f1	Run Formula Lights Program
source ./exe.sh pdf gaussian	Run PDF program for gaussian.mem
source ./exe.sh pdf triangle	Run PDF program for triangle.mem
source ./exe.sh pdf sine	Run PDF program for sine.mem
source ./exe.sh pdf noisy	Run PDF program for noisy.mem

One should first move into the RTL directory before typing in Terminal the commands:

cd RTL

The Formula Lights program has both a RESET and TRIGGER:

• RESET can be controlled by toggling Vbuddy's push-button
• TRIGGER is controlled via the rotary encoder: any value greater than 50 makes Trigger HIGH

To restart the counting sequence, one would have to toggle the push-button, then set the rotary encoder to some value greater than 50.

Our trigger is wired directly to register S3. Please be mindful of this if testing with your own program.

Proof of Successs

PDF	Output	Expected Output
Gaussian
Sine
Triangle
Noisy

Single Cycle CPU:

• Formula Lights
• PDF Gaussian
• PDF Noisy
• PDF Sine
• PDF Triangle

Pipelined CPU:

• Formula Lights
• PDF Gaussian
• PDF Noisy
• PDF Sine
• PDF Triangle

Cache

• Formula Lights

Specifications

Property	Value
Instruction Memory Size	2^12 bits
Instruction Width	32-bit
Data Memory Size	2^17 bit
Data Width	8-bit
Data Cache Size	256 bits
Data Cache Sets	8
Data Cache Ways	1
Data Cache Block Size	4 * 8-bit

Implemented Instructions

Type	Implemented Instructions
R	ADD, SUB, SLL, SLT, SLTU, XOR, SRL, SRA, OR, AND
I	ADDI, SLLI, SLTI, XORI, SRLI, SRAI, ORI, ANDI, LBU, LW, JALR
B	BNE
S	SW, SB
U	LUI
J	JAL

Task Division

		Sara Chehab (sarachehab)	Utsav Goel (utsav254)	Lu Ju (luju1108)	Neil Radhul (Nr722)
General	Top Testbenches			X
	Subfile Testbenches	X	X	C	C
	Shell Script	X
	F1 Assembly	X	X
Single Cycle	Program Counter	X
	Main Decoder	X	X
	Alu Decoder				X
	Control Unit			X	X
	Register File			X
	ALU	C		X
	Data Memory	C			X
	Datapath		C	X
	Sign Extend				X
	Top File	X			X
	Testing pdf F1	X	X	X	X
Pipeline	Pipeline Register	X
	Hazard unit			X
	Refactoring	X
	Top File	X
	Testing pdf F1	X		X
Cache	Direct Mapped Cache	C	X		X
	RAM Refactor		X		X
	Data Memory		X		X
	Control Unit Refactor		X		X
	Pipelining Refactor	X
	Testing	X	X	X	X
	Fully Associative Cache		X		X
	Testing		X		X

Personal Statements

Lu Ju Sara Chehab Utsav Goel Neil Radhul

Final Structure at main

. 
├── lab4 
├── project 
├── data_memory/ 
│ ├── gaussian.mem 
│ ├── noisy.mem 
│ ├── sine.mem 
│ └── triangle.mem 
├── instruction_memory/ 
│ ├── F1.asm 
│ ├── F1.hex 
│ ├── pdf.hex 
│ └── pdf.s
├── project/ 
│ 	├── pc/ 
│ 	│ ├── doit.sh
│ 	│ ├── pc.sv
│ 	├── pc_tb.cpp 
│ 	├── instruction_memory/
│ 	│ ├── doit.sh
│ 	└── ...
└── RTL/ 
	├── control_unit/ 
	│ ├── main_decoder.sv 
	│ ├── alu_decoder.sv 
	│ └── control_unit_top.sv 
	├── data_path/ 
	│ ├── alu.sv 
	│ ├── datapath.sv 
	│ ├── data_memory.sv 
	│ └── register_file.sv 
	├── extend_unit/ 
	│ └── extend_unit.sv 
	├── instruction_memory/ 
	│ └── instruction_memory.sv 
	├── program_counter/ 
	│ └── pc.sv 
	├── cpu.sv 
	├── data_memory.mem 
	├── instructions.hex 
	├── exe.sh 
	├── f1_tb.cpp 
	├── pdf_tb.cpp 
	├── plot_distribution.py 
	├── vbuddy.cpp 
	└── vbuddy.cfg