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Honored ContributorUltrasonic sensor hc-sr04 vhdl code
Hi guys, i found ultrasonic sensor HC-SR04 code implemented in Altera DE2-115 board here https://github.com/rutgers-fpga-projects/ngc-sonar
My project aims to use the Altera DE2 board with ultrasonic sensor HC-SR04 and I modified the declaration of GPIO expansion header to be suited to Altera DE2. Here's the modified codeLIBRARY ieee;USE ieee.std_logic_1164.ALL;
use ieee.numeric_std.ALL;
ENTITY final IS
PORT(
CLOCK_50 : IN STD_LOGIC; -- 50MHz
SW : IN STD_LOGIC_VECTOR(17 DOWNTO 0);
KEY : IN STD_LOGIC_VECTOR(3 DOWNTO 0);
LEDG : OUT STD_LOGIC_VECTOR(7 DOWNTO 0);
LEDR : OUT STD_LOGIC_VECTOR(17 DOWNTO 0);
GPIO_0 : INOUT STD_LOGIC_VECTOR(40 DOWNTO 1);
-- LCD controller stuff
LCD_RS, LCD_EN : OUT STD_LOGIC;
LCD_RW : OUT STD_LOGIC;
LCD_ON : OUT STD_LOGIC;
LCD_DATA : INOUT STD_LOGIC_VECTOR(7 DOWNTO 0)
);
END final;
ARCHITECTURE arch OF final IS
-- convert our 2 digits of hex to 3 digits of BCD
FUNCTION to_bcd ( bin : STD_LOGIC_VECTOR(7 DOWNTO 0) ) RETURN STD_LOGIC_VECTOR IS
VARIABLE i : integer:=0;
VARIABLE bcd : STD_LOGIC_VECTOR(11 DOWNTO 0) := (OTHERS => '0');
VARIABLE bint : STD_LOGIC_VECTOR(7 DOWNTO 0) := bin;
BEGIN
FOR i IN 0 TO 7 LOOP -- repeating 8 times.
bcd(11 DOWNTO 1) := bcd(10 DOWNTO 0); --shifting the bits.
bcd(0) := bint(7);
bint(7 DOWNTO 1) := bint(6 DOWNTO 0);
bint(0) :='0';
IF(i < 7 and bcd(3 DOWNTO 0) > "0100") THEN --add 3 if BCD digit is greater than 4.
bcd(3 DOWNTO 0) := STD_LOGIC_VECTOR(UNSIGNED(bcd(3 DOWNTO 0)) + 3);
END IF;
IF(i < 7 and bcd(7 DOWNTO 4) > "0100") THEN --add 3 if BCD digit is greater than 4.
bcd(7 DOWNTO 4) := STD_LOGIC_VECTOR(UNSIGNED(bcd(7 DOWNTO 4)) + 3);
END IF;
IF(i < 7 and bcd(11 DOWNTO 8) > "0100") THEN --add 3 if BCD digit is greater than 4.
bcd(11 DOWNTO 8) := STD_LOGIC_VECTOR(UNSIGNED(bcd(11 DOWNTO 8)) + 3);
END IF;
END LOOP;
RETURN bcd;
END to_bcd;
-- LCD display controller
COMPONENT LCD_Display IS
PORT(
KEY : IN STD_LOGIC_VECTOR(0 downto 0);
CLOCK_50 : IN STD_LOGIC;
Hex_Display_Data : IN STD_LOGIC_VECTOR(11 DOWNTO 0); --STD_LOGIC_VECTOR((Num_Hex_Digits*4)-1 DOWNTO 0);
LCD_RS, LCD_EN : OUT STD_LOGIC;
LCD_RW : OUT STD_LOGIC;
LCD_ON : OUT STD_LOGIC;
LCD_DATA : INOUT STD_LOGIC_VECTOR(7 DOWNTO 0);
inch_cent_switch : IN STD_LOGIC;
lds : IN STD_LOGIC_VECTOR(15 DOWNTO 0));
END COMPONENT;
SIGNAL graphical_length_display : STD_LOGIC_VECTOR(15 DOWNTO 0);
SIGNAL reset: STD_LOGIC;
SIGNAL trigger : INTEGER:= 500; -- 10us
SIGNAL counter : INTEGER;
SIGNAL MAX_CYCLES : INTEGER; -- number of cycles per sample cycle
SIGNAL count_dist: INTEGER; -- number of in/cm
SIGNAL hex: STD_LOGIC_VECTOR (7 DOWNTO 0);
SIGNAL decimal : STD_LOGIC_VECTOR(11 DOWNTO 0);
SIGNAL inch_conversion_factor : INTEGER := 7231;
SIGNAL cent_conversion_factor : INTEGER := 2847;
SIGNAL inch_cent_switch : STD_LOGIC;
SIGNAL sample_speed_switch : STD_LOGIC;
SIGNAL max_inches : INTEGER := 120;
SIGNAL max_centimeters : INTEGER := 300;
SIGNAL startcount, elapsed : INTEGER;
BEGIN
reset <= NOT KEY(1);
inch_cent_switch <= SW(0); -- 0 = centimeter, 1 = inch
sample_speed_switch <= SW(1);
-- set sample rate
WITH sample_speed_switch SELECT
MAX_CYCLES <= 50000000 WHEN '0', -- 1 sample per second
12500000 WHEN '1'; -- 4 samples per second
-- sampling cycle loop
-- increments counter variable and resets when sampling cycle is over
PROCESS(RESET, CLOCK_50)
BEGIN
IF reset='1' THEN
counter<= 0;
ELSIF RISING_EDGE(CLOCK_50) THEN
counter <= counter +1;
IF(counter > MAX_CYCLES) THEN
counter <= 0;
END IF;
END IF;
END PROCESS;
-- trigger signal
PROCESS(counter)
BEGIN
IF(counter < trigger) THEN -- 0 to 10us
GPIO_0(3) <= '1'; -- trigger
ELSE
GPIO_0(3) <= '0';
END IF;
END PROCESS;
-- echo signal listener
PROCESS(GPIO_0(1))
BEGIN
IF(RISING_EDGE(GPIO_0(1))) THEN
startcount <= counter;
ELSIF(FALLING_EDGE(GPIO_0(1))) THEN
elapsed <= counter - startcount; -- gets length of echo pulse
IF(inch_cent_switch = '0') THEN
count_dist <= elapsed / cent_conversion_factor; -- convert length in clocks to length in centimeters
-- determine bar length for display
IF(count_dist > (max_centimeters * 15) / 16) THEN
graphical_length_display <= "1111111111111111";
ELSIF(count_dist > (max_centimeters * 14) / 16) THEN
graphical_length_display <= "1111111111111110";
ELSIF(count_dist > (max_centimeters * 13) / 16) THEN
graphical_length_display <= "1111111111111100";
ELSIF(count_dist > (max_centimeters * 12) / 16) THEN
graphical_length_display <= "1111111111111000";
ELSIF(count_dist > (max_centimeters * 11) / 16) THEN
graphical_length_display <= "1111111111110000";
ELSIF(count_dist > (max_centimeters * 10) / 16) THEN
graphical_length_display <= "1111111111100000";
ELSIF(count_dist > (max_centimeters * 9) / 16) THEN
graphical_length_display <= "1111111111000000";
ELSIF(count_dist > (max_centimeters * 8) / 16) THEN
graphical_length_display <= "1111111110000000";
ELSIF(count_dist > (max_centimeters * 7) / 16) THEN
graphical_length_display <= "1111111100000000";
ELSIF(count_dist > (max_centimeters * 6) / 16) THEN
graphical_length_display <= "1111111000000000";
ELSIF(count_dist > (max_centimeters * 5) / 16) THEN
graphical_length_display <= "1111110000000000";
ELSIF(count_dist > (max_centimeters * 4) / 16) THEN
graphical_length_display <= "1111100000000000";
ELSIF(count_dist > (max_centimeters * 3) / 16) THEN
graphical_length_display <= "1111000000000000";
ELSIF(count_dist > (max_centimeters * 2) / 16) THEN
graphical_length_display <= "1110000000000000";
ELSIF(count_dist > (max_centimeters * 1) / 16) THEN
graphical_length_display <= "1100000000000000";
ELSIF(count_dist > (max_centimeters * 0) / 16) THEN
graphical_length_display <= "1000000000000000";
END IF;
ELSIF(inch_cent_switch = '1') THEN
count_dist <= elapsed / inch_conversion_factor; -- convert length in clocks to length in inches
-- determine bar length for display
IF(count_dist > (max_inches * 15) / 16) THEN
graphical_length_display <= "1111111111111111";
ELSIF(count_dist > (max_inches * 14) / 16) THEN
graphical_length_display <= "1111111111111110";
ELSIF(count_dist > (max_inches * 13) / 16) THEN
graphical_length_display <= "1111111111111100";
ELSIF(count_dist > (max_inches * 12) / 16) THEN
graphical_length_display <= "1111111111111000";
ELSIF(count_dist > (max_inches * 11) / 16) THEN
graphical_length_display <= "1111111111110000";
ELSIF(count_dist > (max_inches * 10) / 16) THEN
graphical_length_display <= "1111111111100000";
ELSIF(count_dist > (max_inches * 9) / 16) THEN
graphical_length_display <= "1111111111000000";
ELSIF(count_dist > (max_inches * 8) / 16) THEN
graphical_length_display <= "1111111110000000";
ELSIF(count_dist > (max_inches * 7) / 16) THEN
graphical_length_display <= "1111111100000000";
ELSIF(count_dist > (max_inches * 6) / 16) THEN
graphical_length_display <= "1111111000000000";
ELSIF(count_dist > (max_inches * 5) / 16) THEN
graphical_length_display <= "1111110000000000";
ELSIF(count_dist > (max_inches * 4) / 16) THEN
graphical_length_display <= "1111100000000000";
ELSIF(count_dist > (max_inches * 3) / 16) THEN
graphical_length_display <= "1111000000000000";
ELSIF(count_dist > (max_inches * 2) / 16) THEN
graphical_length_display <= "1110000000000000";
ELSIF(count_dist > (max_inches * 1) / 16) THEN
graphical_length_display <= "1100000000000000";
ELSIF(count_dist > (max_inches * 0) / 16) THEN
graphical_length_display <= "1000000000000000";
END IF;
END IF;
END IF;
END PROCESS;
-- get hex out of integer
hex <= STD_LOGIC_VECTOR(TO_UNSIGNED(count_dist, 8));
-- get BCD out of hex
decimal <= to_bcd(hex);
-- instantiate LCD controller
lcd : LCD_Display PORT MAP(KEY(0 DOWNTO 0),CLOCK_50, decimal,LCD_RS, LCD_EN,LCD_RW ,LCD_ON,LCD_DATA, inch_cent_switch, graphical_length_display);
END arch;
