bcd counter with mode control & parallel load capability

Prepared by:Rathod Gaurang

ME1212, EC

BCD counter with mode control & parallel load capability

09 August 2012 rathodgaurang@hotmail.com

BASIC BLOCK DIAGRAM

BCD COUNTER USING MODE CONTROL

LOAD

MODE

CLOCK

RESET

INPUTS

OUTPUT

USING BEHAVIORAL METHOD

VHDL CODE

• entity hb is• Port ( in1 : in STD_LOGIC_vector(3 downto 0); -- load inputs• out1 : out STD_LOGIC_vector(3 downto 0); -- counter output • clk : in STD_LOGIC; -- clock input• ld1 : in STD_LOGIC; -- load control input• mode : in STD_LOGIC; -- mode control input : '1' for up and '0' for down count• clr : in std_logic); -- reset (clear) input : active high• end hb;

•  architecture Behavioral of hb is• begin•  process(in1,mode,ld1,clr,clk)• variable t: std_logic_vector(3 downto 0) :="0000"; --temperary variable that store count• begin• if ( clk' event and clk = '1') then -- for rising clock edge trigger•• if(clr)='1' then t:="0000"; -- reset the count to zero•  • elsif (ld1 and not clr) = '1' then t := in1; --load the count•  • elsif (mode and not ld1 and not clr) = '1' then t:=t+1; --for up count• if (t="1010") then t:="0000"; end if;•  • elsif (not mode and not ld1 and not clr) = '1' then t:=t-1; --for down count• if(t="1111") then t:="1001"; end if;•   end if; • end if; • out1 <= t; -- data store in temperary variable is given to outputs• end process;• end Behavioral;

SIMULATION

WAVEFORM

RTL SCHEMATIC

USING

DATA FLOW

METHOD

VHDL CODE

entity ctr_df is Port ( mode : in STD_LOGIC; -- mode control input: 1 for up & 0 for down counter in1 : in STD_LOGIC_VECTOR (03 downto 0); -- parallel load input out1 : out STD_LOGIC_VECTOR (03 downto 0); -- counter output ld1 : in STD_LOGIC; --parallel load control bit clr : in STD_LOGIC; -- reset bit clk : in STD_LOGIC); --clock inputend ctr_df;architecture Behavioral of ctr_df issignal temp : std_logic_vector(3 downto 0) := "0000"; begintemp <= "0000" when ( clr = '1') else – reset

in1 when (clr = '0' and ld1 = '1' and clk = '1') else -- load input-- up count"0001" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0000") else "0010" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0001") else "0011" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0010") else "0100" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0011") else "0101" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0100") else "0110" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0101") else "0111" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0110") else "1000" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "0111") else "1001" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "1000") else "0000" after 200 ns when (clr = '0' and ld1 = '0' and mode = '1' and temp = "1001") else

-- down counter

"1001" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0000") else

"1000" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "1001") else

"0111" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "1000") else

"0110" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0111") else

"0101" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0110") else

"0100" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0101") else

"0011" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0100") else

"0010" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0011") else

"0001" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0010") else

"0000" after 200 ns when (clr = '0' and ld1 = '0' and mode = '0' and temp = "0001") else

temp after 200 ms;out1 <= temp; --give outputend Behavioral;

SIMULATION

WAVEFORM

1

CLK

RTL SCHEMATIC

1

CLK

BASIC BLOCK DIAGRAM

1

CLK

VHDL CODE

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.STD_LOGIC_ARITH.ALL;use IEEE.STD_LOGIC_UNSIGNED.ALL;

---- Uncomment the following library declaration if instantiating---- any Xilinx primitives in this code.--library UNISIM;--use UNISIM.VComponents.all;

entity countstruct is Port ( clock : in STD_LOGIC; reset : in STD_LOGIC; M : in STD_LOGIC;

count: out STD_LOGIC_VECTOR (3 downto 0)); end countstruct;

architecture Structural of countstruct iscomponent or_3

port ( a : in std_logic; b : in std_logic;

c : in std_logic; q : out std_logic);

end component;

component or_4port ( a : in std_logic; b : in std_logic;

c : in std_logic; d : in std_logic;

q : out std_logic);end component;

component tffport ( clk : in std_logic; rst : in std_logic; data : in std_logic;

q : out std_logic);end component;

signal o1,o2,o3,Iinv0,Iinv1,Iinv2,Iinv3,Minv,n1,n2,n3,n4,m1,m2,m3,v1,v2,v3: std_logic;signal Q : STD_LOGIC_VECTOR (3 downto 0):="0000";

beginIinv0 <= not Q(0);Iinv1 <= not Q(1);Iinv2 <= not Q(2);Iinv3 <= not Q(3);Minv <= not M;

n1 <=Q(3) and Iinv0 and Minv;n2 <=Iinv3 and Q(0) and M;n3 <=Q(1) and Iinv0 and Minv;n4 <=(Q(2) and Iinv0 and Minv);m1 <=(Q(2) and Iinv1 and Iinv0 and Minv);m2 <=(Q(3) and Iinv0 and Minv);m3 <=(Q(1) and Q(0) and M);v1 <=(Iinv2 and Iinv1 and Iinv0 and Minv);v2 <=(Q(3) and Q(0) and M);v3 <=(Q(2) and Q(1) and Q(0) and M);

U1 : or_4 port map (n1,n2,n3,n4,o1);U2 : or_3 port map (m1,m2,m3,o2);U3 : or_3 port map (v1,v2,v3,o3);U4 : tff port map (clock,reset,'1',Q(0));U5 : tff port map (clock,reset,o1,Q(1));U6 : tff port map (clock,reset,o2,Q(2));U7 : tff port map (clock,reset,o3,Q(3));

count <= Q ;

end Structural;

RTL SCHEMATIC

APPLICATIONS OF COUNTER

Many applications use counters

Digital Clocks Automobile Parking Control Parallel-to-Serial Data Conversion A/D Converters Frequency Meters/Counters Signal Generators Microprocessors

UP-DOWN COUNTER APPLICATION AS A SEMI-AUTOMATED PARKING LOT

GATE

WHEN A CAR APPROACHES THE ENTER GATE ON THE RIGHT, THE DRIVER PUSHES A BUTTON TO

DISCHARGE THE TICKET, AND THE GATE OPENS UNTIL THE CAR PASSES

WHEN THE ENTER GATE COMES FULLY DOWN, IT CLOSES A LIMIT SWITCH THAT CAUSES THE PLC

COUNTERS TO INCREMENT

TO EXIT THE PARKING AREA,DRIVER PRESENTS A TICKET TO THE CASHIER AT THE WINDOW. AFTER

PAYMENT,THE EXIT GATE IS OPENED UNTIL THE CAR PASSES.

WHEN THE EXIT GATE COMES FULLY DOWN,IT CLOSES THE LIMIT SWITCH THAT CAUSES THE PLC

COUNTERS TO DECREMENT

CAPACITY OF PARKING LOT IS 100 CARS

WHEN THE COUNT IS BETWEEN 0 AND 99, THE VACANCY LIGHT TURNS ON

WHEN THE 100TH CAR ENTERS,PLC COUNTERS INCREMENT,TURNING OFF THE VACANCY LIGHT AND

ILLUMINATING THE FULL LIGHT

THANK YOU