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 BUS [7:0] CPU ENB ENB ENB ENB Grant-8bits [7:0] Arbiter Request-8bits Priority-24bits 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 Selection bit roundORpriority equal 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 Selection bit roundORpriority equal 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 d) Multi request with random priority - priority = $random(); e) Multi request with random request and priority $ramdom() - 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, 5-6-7-0-12-3-4 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 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) 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) 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 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