Homework 21 arbiter and test bench verilog

Arbiter Operates: Arbiter is a device used in a multimaster bus system to decide which bus master will be allowed to control the bus for each bus cycle. The input of arbiter inclusion: request (8bits), priority (24bits), roundORpriority (1bit), reset (1bit), clock. The output of arbiter inclusion: bits of grant (8bits)

VLSI DESIGN AUTOMATION

Homework #2

Test bench for Arbiter

Student: Bui Huu Nguyen

ID number: 2016310539

Submission Date: 2016/10/06

Arbiter

ENB

ENB

ENB

ENB

ENB

ENB

ENB

ENB

Grant-8bits [7:0]

BUS

[7:0]

Arbiter

CPU

Priority-24bits Request-8bits RoundORpriority-1bit Reset-1bit Clock

Figure 1: Diagram input and output of Arbiter Arbiter Operates:

- Arbiter is a device used in a multi-master bus system to decide which bus master will be allowed to control the bus for each bus cycle

- The input of arbiter inclusion: request (8bits), priority (24bits), roundORpriority (1bit), reset (1bit), clock

- The output of arbiter inclusion: bits of grant (8bits)

A Write test bench

1 Selection bit roundORpriority equal 0 that has round mode

0-1-2-3-4-5-6-7

Figure 2: Round mode a) Single request

- Value of input “request” will be changed one bit flowing table

00000001 00000010 00000100 00001000 00010000 00100000 01000000 10000000

b) Multi request

- Value of input “request” will be changed as flowing table

11000000 11100000 00001111 11110000 11100111

2 Selection bit roundORpriority equal 1 that has priority mode

c) Multi request with different priority

- Set input “priority” to a specific value:

Request: 7-6-5-4-3-2-1-0

Order: 5-6-7-0-1-2-3-4

 Priority: 24’b101-110-111-000-001-010-011-100

- Value of input “request” will be changed as flowing table

11100000 01110000 01111000 $ramdom()

d) Multi request with random priority

- priority = $random();

e) Multi request with random request and priority

- request = $random(); priority = $random();

Code Abiter test bench

`timescale 1ns / 100 ps

module arbiter_tb();

//integer i,j,k,p,q,r,s,t,u,v ; //index for "for" loops

// -

// parameters

// -

parameter NUMUNITS = 8;

parameter ADDRESSWIDTH = 3; //number of bits needed to address NUMUNITS // -

// input and output declarations

// -

reg clock;

reg reset;

reg roundORpriority;

reg [NUMUNITS-1 : 0] request;

reg [ADDRESSWIDTH*NUMUNITS-1 : 0] priority;

wire [NUMUNITS-1 : 0] grant;

//arbiter x(clock, reset, roundORpriority, request, priority,grant);

initial begin

reset = 0;

clock = 0;

request = 8'b0;

roundORpriority = 1'b0; // round mode priority = 24'h000000;

#10 reset = 1;

//roundORpriority = 2'b00;

//single request

request = 8'b00000001;

#10

request = 8'b00000010;

#10

request = 8'b00000100;

#10

request = 8'b00001000;

#10

request = 8'b00010000;

#10

request = 8'b00100000;

#10

request = 8'b01000000;

#10

request = 8'b10000000;

//multi request

#10

request = 8'b11000000;

#10

request = 8'b11100000;

#10

request = 8'b00001111;

#10

request = 8'b11110000;

#10

request = 8'b11100111;

//Priority mode

roundORpriority = 1'b1; // priority mode

priority = 24'b101110111000001010011100; // 7-6-5-4-3-2-1-0 request, 5-6-7-0-1-2-3-4 priority

#10

request = 8'b11100000;

#10

request = 8'b01110000;

#10

request = 8'b01111000;

#10

request = $random(); // random request

// random priority

#10

priority = $random();

#10

request = 8'b11100000;

#10

request = 8'b01110000;

#10

request = 8'b01111000;

// random priority and random request

#10

priority = $random();

#10

request = $random();

end

always #5 clock = ! clock;

arbiter u0(.clock (clock),.reset (reset),.roundORpriority (1'b0),.request(request),.priority (priority),.grant (grant));

endmodule

B Simulation result

1 RoundORpriority = 0, round mode

a) Single request

-request: 00000001->grant:00000001

b Multi request

-request: 10000000  grant: 10000000 (7)

-request: 11000000  grant: 01000000 (6)

-request: 11100000  grant: 10000000 (7)

-request: 00001111  grant: 00000001 (1)

2 RoundORpriority = 0, priority mode

-request: 11100000  grant: 10000000

0-1-2-3-4-5-6-7

-request: 01110000  grant: 00010000

-request: 01111000  grant: 00010000

-request: 00100100  grant: 00000100 (random request)

3 Multi request with random priority

-priority: 24’h895e81 = 24’b100-010-010-101-111-010-000-001

-Order: 4-2-2-5-7-2-0-1

-request: 7-6-5-4-3-2-1-0

-request: 11100000  grant: 0100000

-request: 01110000  grant: 0100000

-request: 01111000  grant: 0010000

4 Multi request with random request and priority

-priority: 24’h84d609 = 24’b100-001-001-101-011-000-001-001

-Order: 4-1-1-5-3-0-1-1

-request: 7-6-5-4-3-2-1-0

-request: 01100011  grant: 0100000 or 00000001 or 00000010 or 00100000 or

01000000