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max_uart_vhdl
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UART TX module works.

master
Maximilian Stiefel 5 years ago
parent
41d09c015e
commit
885e45b3c2
6 changed files with 163 additions and 87 deletions
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  1. 14
      adder.vhdl
  2. 56
      adder_tb.vhdl
  3. 17
      hello.vhdl
  4. 30
      uart_tx.gtkw
  5. 55
      uart_tx.vhdl
  6. 78
      uart_tx_tb.vhdl

14
adder.vhdl
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@ -1,14 +0,0 @@
entity adder is
-- i0, i1 and the carry-in ci are inputs of the adder.
-- s is the sum output, co is the carry-out.
port (i0, i1 : in bit; ci : in bit; s : out bit; co : out bit);
end adder;
architecture rtl of adder is
begin
-- This full-adder architecture contains two concurrent assignment.
-- Compute the sum.
s <= i0 xor i1 xor ci;
-- Compute the carry.
co <= (i0 and i1) or (i0 and ci) or (i1 and ci);
end rtl;

56
adder_tb.vhdl
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@ -1,56 +0,0 @@
-- A testbench has no ports.
entity adder_tb is
end adder_tb;
architecture behav of adder_tb is
-- Declaration of the component that will be instantiated.
component adder
port (i0, i1 : in bit; ci : in bit; s : out bit; co : out bit);
end component;
-- Specifies which entity is bound with the component.
for adder_0: adder use entity work.adder;
signal i0, i1, ci, s, co : bit;
begin
-- Component instantiation.
adder_0: adder port map (i0 => i0, i1 => i1, ci => ci,
s => s, co => co);
-- This process does the real job.
process
type pattern_type is record
-- The inputs of the adder.
i0, i1, ci : bit;
-- The expected outputs of the adder.
s, co : bit;
end record;
-- The patterns to apply.
type pattern_array is array (natural range <>) of pattern_type;
constant patterns : pattern_array :=
(('0', '0', '0', '0', '0'),
('0', '0', '1', '1', '0'),
('0', '1', '0', '1', '0'),
('0', '1', '1', '0', '1'),
('1', '0', '0', '1', '0'),
('1', '0', '1', '0', '1'),
('1', '1', '0', '0', '1'),
('1', '1', '1', '1', '1'));
begin
-- Check each pattern.
for i in patterns'range loop
-- Set the inputs.
i0 <= patterns(i).i0;
i1 <= patterns(i).i1;
ci <= patterns(i).ci;
-- Wait for the results.
wait for 1 ns;
-- Check the outputs.
assert s = patterns(i).s
report "bad sum value" severity error;
assert co = patterns(i).co
report "bad carray out value" severity error;
end loop;
assert false report "end of test" severity note;
-- Wait forever; this will finish the simulation.
wait;
end process;
end behav;

17
hello.vhdl
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@ -1,17 +0,0 @@
-- Hello world program.
use std.textio.all; -- Imports the standard textio package.
-- Defines a design entity, without any ports.
entity hello_world is
end hello_world;
architecture behaviour of hello_world is
begin
process
variable l : line;
begin
write (l, String'("Hello world!"));
writeline (output, l);
wait;
end process;
end behaviour;

30
uart_tx.gtkw
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@ -0,0 +1,30 @@
[*]
[*] GTKWave Analyzer v3.3.98 (w)1999-2019 BSI
[*] Mon Jul 6 17:13:37 2020
[*]
[dumpfile] "/home/maximilian/vga_uart_grabber_vhdl/uart_tx.vcd"
[dumpfile_mtime] "Mon Jul 6 17:13:29 2020"
[dumpfile_size] 4538783
[savefile] "/home/maximilian/vga_uart_grabber_vhdl/uart_tx.gtkw"
[timestart] 0
[size] 1920 1051
[pos] 3 0
*-33.258671 3810000000000 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
[treeopen] uart_tx_tb.
[sst_width] 212
[signals_width] 182
[sst_expanded] 1
[sst_vpaned_height] 300
@28
uart_tx_tb.uart_tx_0.i_clk_baudrate
uart_tx_tb.uart_tx_0.i_reset_n
@22
uart_tx_tb.uart_tx_0.i_tx_data_vec[7:0]
@28
uart_tx_tb.uart_tx_0.i_tx_send
uart_tx_tb.uart_tx_0.o_tx_pin
uart_tx_tb.uart_tx_0.o_tx_sent
@23
uart_tx_tb.uart_tx_0.s_tx_buf_vec[7:0]
[pattern_trace] 1
[pattern_trace] 0

55
uart_tx.vhdl
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@ -0,0 +1,55 @@
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity uart_tx is
port(
i_clk_baudrate : in std_logic;
i_reset_n : in std_logic;
i_tx_send : in std_logic;
i_tx_data_vec : in std_logic_vector(7 downto 0);
o_tx_pin : out std_logic;
o_tx_sent : out std_logic
);
end;
architecture uart_tx_rtl of uart_tx is
type z_uart_t is (idle, sending);
constant c_START_BIT : std_logic := '0';
constant c_STOP_BIT : std_logic := '1';
signal s_tx_buf_vec : std_logic_vector(7 downto 0) := x"00";
begin
uart_tx_main_proc: process(i_clk_baudrate)
variable z_uart : z_uart_t := idle;
variable v_trans_cnt : integer range 0 to 10 := 0;
begin
if rising_edge(i_clk_baudrate) then
-- Syncrhonous reset only.
if (i_reset_n = '0') then
o_tx_pin <= '1';
o_tx_sent <= '1';
z_uart := idle;
else
case z_uart is
when idle =>
if (i_tx_send = '1') then
s_tx_buf_vec <= i_tx_data_vec;
o_tx_sent <= '0';
o_tx_pin <= c_START_BIT;
z_uart := sending;
end if;
when sending =>
if (v_trans_cnt >= 8) then
v_trans_cnt := 0;
o_tx_sent <= '1';
o_tx_pin <= c_STOP_BIT;
z_uart := idle;
else
o_tx_pin <= s_tx_buf_vec(7-v_trans_cnt);
v_trans_cnt := v_trans_cnt + 1;
end if;
end case;
end if; -- reset
end if; -- clk
end process uart_tx_main_proc; -- main
end;

78
uart_tx_tb.vhdl
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@ -0,0 +1,78 @@
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
-- Testbenches do not have ports.
entity uart_tx_tb is
end uart_tx_tb;
architecture uart_tx_tb_rtl of uart_tx_tb is
-- 10 MHz clock
constant c_CLK_PERIOD : time := 100 ns;
--Declaration of component we will instantiate.
component uart_tx
port (
i_clk_baudrate : in std_logic;
i_reset_n : in std_logic;
i_tx_send : in std_logic;
i_tx_data_vec : in std_logic_vector(7 downto 0);
o_tx_pin : out std_logic;
o_tx_sent : out std_logic
);
end component;
-- Which entity is bound with the component.
for uart_tx_0: uart_tx use entity work.uart_tx;
-- Signals for test stimuli.
signal tb_i_clk_baudrate : std_logic := '0';
signal tb_i_reset_n : std_logic := '0';
signal tb_i_tx_send : std_logic := '0';
signal tb_i_tx_data_vec : std_logic_vector(7 downto 0) := x"00";
signal tb_o_tx_pin : std_logic := '0';
signal tb_o_tx_sent : std_logic := '0';
signal tb_done : std_logic := '0';
begin
-- Instatiating component.
uart_tx_0: uart_tx port map (
i_clk_baudrate => tb_i_clk_baudrate,
i_reset_n => tb_i_reset_n,
i_tx_send => tb_i_tx_send,
i_tx_data_vec => tb_i_tx_data_vec,
o_tx_pin => tb_o_tx_pin,
o_tx_sent => tb_o_tx_sent
);
-- Generate clock.
p_clock : process is
begin
if (tb_done = '0') then
tb_i_clk_baudrate <= '0';
wait for c_CLK_PERIOD/2;
tb_i_clk_baudrate <= '1';
wait for c_CLK_PERIOD/2;
elsif tb_done = '1' then
wait;
end if;
end process p_clock;
-- Generate further testing stimuli in addition.
p_stimuli : process is
type vector_array_t is array (0 to 3) of std_logic_vector(7 downto 0);
constant nice_words : vector_array_t := (x"BE", x"EF", x"BA", x"BE");
begin
-- Reset transmitter.
tb_i_reset_n <= '0';
wait for c_CLK_PERIOD;
tb_i_reset_n <= '1';
for sanny in nice_words'range loop
-- Feed with data and tell transmitter to send.
tb_i_tx_data_vec <= nice_words(sanny);
tb_i_tx_send <= '1';
-- Wait until transmitted then finish simulation.
wait until tb_o_tx_sent = '1';
tb_i_tx_send <= '0';
wait for c_CLK_PERIOD*1.5;
end loop;
tb_done <= '1';
assert false report "end of test" severity note;
wait;
-- Wait forever, which will finish the simulation.
end process p_stimuli;
end uart_tx_tb_rtl;
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