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198 lines
6.1 KiB
198 lines
6.1 KiB
-- ======================================================================
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-- UART testbench
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-- Copyright (C) 2020 Torsten Meissner
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-------------------------------------------------------------------------
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-- This program is free software; you can redistribute it and/or
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-- modify it under the terms of the GNU Lesser General Public
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-- License as published by the Free Software Foundation; either
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-- version 3 of the License, or (at your option) any later version.
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--
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-- This program is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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-- Lesser General Public License for more details.
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--
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-- You should have received a copy of the GNU Lesser General Public License
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-- along with this program; if not, write to the Free Software Foundation,
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-- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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-- ======================================================================
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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library osvvm;
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use osvvm.RandomPkg.all;
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use osvvm.CoveragePkg.all;
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use std.env.all;
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entity UartT is
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end entity UartT;
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architecture sim of UartT is
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constant c_data_length : positive range 5 to 9 := 8;
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constant c_parity : boolean := true;
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constant c_clk_div : natural := 10;
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signal s_reset_n : std_logic := '0';
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signal s_clk : std_logic := '1';
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signal s_tx_data : std_logic_vector(c_data_length-1 downto 0);
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signal s_tx_valid : std_logic;
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signal s_tx_accept : std_logic;
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signal s_rx_data : std_logic_vector(c_data_length-1 downto 0);
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signal s_rx_error : std_logic;
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signal s_rx_valid : std_logic;
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signal s_rx_accept : std_logic;
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signal s_tx_uart : std_logic := '1';
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signal s_rx_uart : std_logic := '1';
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type t_error is (NONE, DATA, STOP);
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signal s_error_inject : t_error := NONE;
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signal s_error_injected : t_error := NONE;
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shared variable sv_uart_err_coverage : CovPType;
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procedure injectError (signal inject : out t_error) is
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variable v_injected : boolean;
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variable v_random : RandomPType;
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begin
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v_random.InitSeed(v_random'instance_name & to_string(now));
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loop
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-- Wait for new UART transmission
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v_injected := false;
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wait until s_tx_valid = '1' and s_tx_accept = '1';
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wait until falling_edge(s_tx_uart);
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-- Skip start bit
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for i in 0 to c_clk_div-1 loop
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wait until rising_edge(s_clk);
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end loop;
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-- Possibly distort one of the data bits
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-- and update coverage object
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for i in 0 to c_data_length loop
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if (not v_injected and v_random.DistValInt(((0, 9), (1, 1))) = 1) then
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v_injected := true;
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sv_uart_err_coverage.ICover(i);
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if (i = c_data_length) then
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inject <= STOP;
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report "Injected transmit error on stop bit";
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else
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inject <= DATA;
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report "Injected transmit error on data bit #" & to_string(i);
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end if;
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end if;
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for y in 0 to c_clk_div-1 loop
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wait until rising_edge(s_clk);
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end loop;
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inject <= NONE;
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end loop;
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end loop;
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wait;
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end procedure injectError;
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begin
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Dut_UartTx : entity work.UartTx
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generic map (
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DATA_LENGTH => c_data_length,
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PARITY => c_parity,
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CLK_DIV => c_clk_div
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)
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port map (
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reset_n_i => s_reset_n,
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clk_i => s_clk,
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data_i => s_tx_data,
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valid_i => s_tx_valid,
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accept_o => s_tx_accept,
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tx_o => s_tx_uart
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);
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-- Error injection based on random
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sv_uart_err_coverage.AddBins("DATA_ERROR", GenBin(0, c_data_length-1));
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sv_uart_err_coverage.AddBins("STOP_ERROR", GenBin(c_data_length));
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injectError(s_error_inject);
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s_rx_uart <= s_tx_uart when s_error_inject = NONE else not(s_tx_uart);
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Dut_UartRx : entity work.UartRx
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generic map (
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DATA_LENGTH => c_data_length,
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PARITY => c_parity,
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CLK_DIV => c_clk_div
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)
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port map (
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reset_n_i => s_reset_n,
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clk_i => s_clk,
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data_o => s_rx_data,
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error_o => s_rx_error,
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valid_o => s_rx_valid,
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accept_i => s_rx_accept,
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rx_i => s_rx_uart
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);
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s_clk <= not s_clk after 5 ns;
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s_reset_n <= '1' after 20 ns;
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-- Store if an error was injected in the current frame
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s_error_injected <= s_error_inject when rising_edge(s_clk) and s_error_inject /= NONE else
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NONE when s_tx_valid = '1';
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TestP : process is
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variable v_data : std_logic_vector(c_data_length-1 downto 0);
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variable v_random : RandomPType;
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begin
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v_random.InitSeed(v_random'instance_name);
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s_tx_valid <= '0';
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s_rx_accept <= '0';
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s_tx_data <= (others => '0');
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wait until s_reset_n = '1';
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for i in 0 to 2**c_data_length-1 loop
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wait until rising_edge(s_clk);
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s_tx_valid <= '1';
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s_rx_accept <= '1';
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v_data := v_random.RandSlv(8);
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s_tx_data <= v_data;
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report "Testcase #" & to_string(i) & ": Transmit 0x" & to_hstring(v_data);
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wait until rising_edge(s_clk) and s_tx_accept = '1';
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s_tx_valid <= '0';
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wait until rising_edge(s_clk) and s_rx_valid = '1';
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if s_error_injected /= NONE then
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if s_error_injected = DATA then
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assert s_rx_data /= v_data
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report "Received data 0x" & to_hstring(s_rx_data) & ", expected 0x" & to_hstring(v_data)
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severity failure;
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end if;
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assert s_rx_error = '1'
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report "Received error 0b" & to_string(s_rx_error) & ", expected 0b1"
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severity failure;
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else
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assert s_rx_data = v_data
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report "Received data 0x" & to_hstring(s_rx_data) & ", expected 0x" & to_hstring(v_data)
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severity failure;
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assert s_rx_error = '0'
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report "Received error 0b" & to_string(s_rx_error) & ", expected 0b0"
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severity failure;
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end if;
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end loop;
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wait for 10 us;
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sv_uart_err_coverage.SetMessage("UART bit error coverage");
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sv_uart_err_coverage.WriteBin;
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finish(0);
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end process TestP;
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end architecture sim;
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