|
Posted on:
|
I wanted to make a vco to get 8 different values of frequencies dependent on controlfreq input and I made it successfully but for now I want to add another single bit input so when its value is '1' I divide each frequency of those by 1000 or in other words to get frequency by hertz instead of kilo hertz .. here's my code
library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_unsigned.ALL; entity VCO is port ( controlfreq: in std_logic_vector(2 downto 0); clock_out: out std_logic); end VCO; architecture bhv of VCO is signal clk : std_logic; signal div : std_logic_vector(7 downto 0):=(others=>'0'); begin process(clk) begin if(clk'event and clk='1') then div <= div + '1'; end if; end process; process(clk) begin if (controlfreq <= "000") then clock_out <= div(0); elsif (controlfreq <= "001") then clock_out <= div(1); elsif (controlfreq <= "010") then clock_out <= div(2); elsif (controlfreq <= "011") then clock_out <= div(3); elsif (controlfreq <= "100") then clock_out <= div(4); elsif (controlfreq <= "101") then clock_out <= div(5); elsif (controlfreq <= "110") then clock_out <= div(6); elsif (controlfreq <= "111") then clock_out <= div(7); end if; end process; end bhv; |
:
Edited by Moderator
|
Posted on:
|
Mohamed H. wrote: > want to add another single bit input so when its value is '1' I divide > each frequency of those by 1000 or in other words to get frequency by > hertz instead of kilo hertz .. here's my code I don't see a real question (mark) here. If you need other frequencies than you need another prescaler. > use IEEE.STD_LOGIC_unsigned.ALL; Don't use this, use ieee.numeric_std.all instead with all proper type definitions. > if(clk'event and clk='1') then rising_edge(clk) is more reader friendly (and has some small advantages in simulation). > if (controlfreq <= "000") then > clock_out <= div(0); > elsif (controlfreq <= "001") then > clock_out <= div(1); > elsif (controlfreq <= "010") then > clock_out <= div(2); > elsif (controlfreq <= "011") then > clock_out <= div(3); > elsif (controlfreq <= "100") then > clock_out <= div(4); > elsif (controlfreq <= "101") then > clock_out <= div(5); > elsif (controlfreq <= "110") then > clock_out <= div(6); > elsif (controlfreq <= "111") then > clock_out <= div(7); I suggest to use the case-construct here. See: https://en.wikibooks.org/wiki/Programmable_Logic/VHDL_Sequential_Statement https://en.wikibooks.org/wiki/VHDL_for_FPGA_Design/Multiplexer Duke
|
Posted on:
|
Mohamed H. wrote: > for now I want to add another single bit input so when its value is '1' > I divide each frequency of those by 1000 You will need an additional prescaler here:
signal prescaler : integer range 0 to 999 := 0; : : if(clk'event and clk='1') then if slowdown = '1' then -- slowdown mode if prescaler = 999 then prescaler <= 0; div <= div + '1'; else prescaler <= prescaler+1; end if; else -- traditional mode div <= div + '1'; end if; end if; : : |
Mohamed H. wrote: > here's my code Pls use the [vhdl] tags as described above every text input box.
Watch this topic
Disable multi-page view