I want to use clock oscillator...

[Altera_Forum]

Hi. I have DE0 board and it has 50MHz clock oscillator. 

I want to make a digital clock, and I know How to change 50MHZ to 1Hz, But I don't know how to make the 50MHz oscillator start. When i push the button or swich, I want to make the 50MHz oscillator start to work. How can I do that? I have user manual , but it doesn't tell me how to do that.

[Altera_Forum]

to slow down your clock: 

 process(n_clr, clk) begin  if(n_clr='0') then  cont_reg <= ( others => '0' );  elsif(clk'event and clk='1') then  cont_reg <= cont_prox;  end if; end process;  cont_prox <= cont_reg + 1 when ( cont_reg < 50000000 and cont_on='1' ) else  ( others => '0' ) when ( cont_reg = 50000000 and cont_on='1' ) else  cont_reg;  tick_1s = '1' when ( cont_reg = 50000000 ) else  '0';   to start your clock with a button make a state machine:  process...  if(n_clr='0') then  est_reg = ini;  elsif(clk....  est_reg <= est_prox;  end....  process(...    est_prox <= est_reg;  cont_on <= '0';   case est_reg is  when ini =>  if (button ='0' ) then  est_prox <= contando;  end if;  when contando =>  cont_on <='1';  ...

[Altera_Forum]

Try to use your clock to create a ramp... that's how you can slow down the clock.

[Altera_Forum]

Thanks buddy! but.. what is the est_prox, est_reg, contando?

[Altera_Forum]

est_reg, est_prox are current and next value of the state register of the state machine. You can declare this way: 

 architecture blablabla of...  type estado is ( ini, contando,.. ); -- only 2 states. I don't know if your design need more.  signal est_reg, est_prox : estado; begin ..... -- here starts the code, process, etc.  As you see, contando is a state of the state machine.