Hi
I am trying to develop a snake game using a Nexys 4 board and oled rgb 
screen.
I can't generate automaticaly an other point on the screen when the 
snake's head meets the food and while the head is moving . My random 
generator(control_pomme) seems to work .  I didn't base my project on 
the use of a RAM , do you think it is necessary because  almost all the 
snake-like  vga projects on the web seem to use this approach .

Thanks for your reply

Ya Y. wrote:
> Thanks for your reply

           b_up       : in STD_LOGIC;
           b_down     : in STD_LOGIC;
           b_left     : in STD_LOGIC;
           b_right    : in STD_LOGIC;

If those are asynchronous real world buttons, then you must sync them 
to your clock. Otherwise you will encouter curious problems.

    type etat is (init, snake_right, snake_left, snake_up, snake_down, snake_pause);
:
:
        case etat_present is
:
:
        when others => go_up <= '0';     --others = snake_down

Instead of "others" you better should have written "snake_down", because 
then there would remain no "others" and the obfuscating "others" clause 
would be not needed.

signal sspixcol : unsigned( 6 downto 0 ):="0110000";
signal sspixrow : unsigned( 5 downto 0 ):="100000";
signal noir : STD_LOGIC_VECTOR (15 downto 0) :="0000000000000000";
signal vert : STD_LOGIC_VECTOR (15 downto 0) :="0000001111100000";
:
:
        sspixrow <= sspixrow - "000001";

Why don't you work with integers throughout? Then you could use "real 
world numbers" instead of unreadable binary codes. And the arithmetic 
operations would be much easier to understand...

signal sspixcol : integer range 0 to 127 := 96;
signal sspixrow : integer range 0 to 63  := 32;
:
:
        sspixrow <= sspixrow - 1;

I use a debouncer for the buttons , all project files are in the second 
post.
Thanks for  the other  remarks