0-15 counter

Here's a guide.

1. Use synchronous design techniques, eg., use the 50MHz clock on your board.

2. Design a synchronizer component, eg., dual DFF for converting an asynchronous external signal to a synchronous signal

3. Synchronize the external push button signals and then debounce them, i.e., check that the button transition from high to low or low to high is clean. You might need to use a counter to decide that button transitions are only recognized if the button state changes and is held for say 10 clocks. The button change can be converted to a single clock period wide pulse, and this can be the enable for your counter that drives the hex display.

4. Design a hex to 7-segment display driver

5. Wire it all together

Don't go searching too far for source code, try and write it yourself, I'll show you examples if you cannot figure it out.

Are you writing VHDL or SystemVerilog code?

What board are you using?

Cheers,

Dave

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I am writing a vhdl code and i cant figure it out

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Which step are you stuck on?

Pick something simple. For example, start with the 7-segment decoder. That circuit can be combinatorial. The component input is 4-bits and the output is the 7-segment 7-bit value. Draw images of the digits 0 through F displayed on a 7-segment display and create a table of which bits need to be on or off. See if you can figure out how to implement that in VHDL. Don't worry if you cannot, just post the table (photo of paper is fine) to show you understand and tried.

Cheers,

Dave

7-segment diaplay 0-F

ABCDEFG

0= 0000001 8= 0000000

1= 1001111 9= 0001100

2= 0010010 A= 0001000

3= 0000110 b= 1100000

4= 1001100 C= 0110001

5= 0100100 d= 1000010

6= 0100000 E= 0110000

7= 0001111 F= 0111000

a '0' means that the segment is on and a '1' means its off that is the table that i created

thanks

Yep, you got it :)

Now look at the VHDL implementation

https://github.com/d-hawkins/hdl/blob/master/lib/hex_display/src/hex_display.vhd

The std_logic_vector(6 downto 0) output is just (G,F,E,D,C,B,A), so the binary values in the table are in bit-reversed order to what you wrote above. That is just an implementation detail :)

Cheers,

Dave

So what step would you like next? How about generating a count on your hex display?

Create a counter that divides your 50MHz clock by "enough bits" that the MSBs change slow enough that you can read them when connected to the hex display.

If you dig around the github repo you'll see examples for some Xilinx boards.

If you tell me what Altera board you are using, I probably have it too, and will post code to that repo.

Cheers,

Dave

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EPM7064SLC84-7 that's the device i am using

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Ah, so not an evaluation board then? Or if it is, it is an ancient one. The Altera UP2 had a EPM7128SLC84-7 device.

An evaluation board is a good investment if you can afford one, since it makes it easier for others with the same hardware to share their designs. It also helps beginners like yourself learn good coding habits.

That being said, your device can be programmed to contain a counter that can blink the LED, and do the other tasks you're interested in learning, so keep going!

Cheers,

Dave

can you help me start of guide me on how to start it this is what i got so far

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity up_down_counter2 is

Port ( CLK : in STD_LOGIC;

DIR : in STD_LOGIC;

LED : out STD_LOGIC_VECTOR (7 downto 0));

end up_down_counter2;

architecture Behavioral of up_down_counter2 is

signal clk_div : STD_LOGIC_VECTOR (5 downto 0);

signal count : STD_LOGIC_VECTOR (7 downto 0);

begin

-- clock divider

process (CLK)

begin

if (CLK'Event and CLK = '1') then

clk_div <= clk_div + '1';

end if;

end process;

-- up/down counter

process (clk_div(5))

begin

if (clk_div(5)'Event and clk_div(5) = '1') then

if (DIR = '1') then

-- count up to 15 then stop

while (count < 15) loop

count <= count + '1'; -- count up

end loop;

else

-- count down to 0 then stop

while (count > 0) loop

count <= count - '1'; -- count down

end loop;

end if;

end if;

end process;

LED <= not count;

end Behavioral;

but this does not use pushbuttons how do i implement pushbuttons and without a timer