112 lines
2.4 KiB
Systemverilog
112 lines
2.4 KiB
Systemverilog
`timescale 1ps/1ps
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/* verilator lint_off DECLFILENAME */
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/* verilator lint_off MULTITOP */
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/* verilator lint_off STMTDLY */
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/* verilator lint_off INFINITELOOP */
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/* verilator lint_off INITIALDLY */
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module i2c_io_output_tb;
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logic clock = 1'b0;
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logic reset = 1'b1;
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/* Master clock 100MHz (10ns period) */
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always #(10ns/2) clock = ~clock;
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parameter SCL_PERIOD = 364793; // ~300ns
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logic scl_async;
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logic sda_async;
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event scl_low_ev;
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event scl_high_ev;
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initial begin
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scl_async = 1'b1;
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forever begin
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#(SCL_PERIOD/4) scl_async = 1'b1;
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#(SCL_PERIOD/4) -> scl_high_ev;
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#(SCL_PERIOD/4) scl_async = 1'b0;
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#(SCL_PERIOD/4) -> scl_low_ev;
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end
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end
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parameter IO_BYTES_COUNT = 2;
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parameter [6:0] I2C_ADDRESS = 7'h5a;
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localparam DATA_WIDTH = IO_BYTES_COUNT * 8;
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logic i_scl;
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logic i_sdi;
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logic o_sdo;
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logic [DATA_WIDTH-1:0] o_data;
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i2c_io_output #(.I2C_ADDR(I2C_ADDRESS),
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.IO_BYTES_COUNT(IO_BYTES_COUNT))
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DUT (.*);
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logic [1:0] scl_sync;
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logic [1:0] sda_sync;
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always_ff @(posedge clock)
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if (reset) begin
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scl_sync <= '1;
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sda_sync <= '1;
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end
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else begin
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scl_sync <= {scl_sync[0], scl_async};
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sda_sync <= {sda_sync[0], sda_async};
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end
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assign i_scl = scl_sync[1];
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assign i_sdi = sda_sync[1];
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task send_start;
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wait(scl_async == 1'b0);
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sda_async = 1'b1;
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@(scl_high_ev);
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sda_async = 1'b0;
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endtask
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task send_stop;
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wait(scl_async == 1'b0);
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sda_async = 1'b0;
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@(scl_high_ev);
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sda_async = 1'b1;
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endtask
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task send_byte(logic [7:0] b);
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for (int n = 7; n >= 0; n -= 1) begin
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@(scl_low_ev);
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sda_async = b[n];
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end
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@(scl_low_ev);
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wait(scl_async == 1'b1);
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endtask
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initial begin
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reset = 1'b1;
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repeat(2) @(posedge clock) #1;
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reset = 1'b0;
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repeat(2) @(posedge clock) #1;
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send_start;
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send_byte(8'hb4);
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send_byte(8'ha5);
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send_byte(8'h38);
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send_byte(8'h42);
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send_stop;
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repeat(1000) @(posedge clock) #1;
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$finish;
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end
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`ifdef DUMP
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initial begin
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$dumpfile("i2c_io_output_tb.fst");
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$dumpvars(0, i2c_io_output_tb);
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end
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`endif
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endmodule // i2c_io_output_tb
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