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

1

           b_up       : in STD_LOGIC;

2

           b_down     : in STD_LOGIC;

3

           b_left     : in STD_LOGIC;

4

           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.

1

    type etat is (init, snake_right, snake_left, snake_up, snake_down, snake_pause);

2

:

3

:

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        case etat_present is

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:

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:

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        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.

1

signal sspixcol : unsigned( 6 downto 0 ):="0110000";

2

signal sspixrow : unsigned( 5 downto 0 ):="100000";

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signal noir : STD_LOGIC_VECTOR (15 downto 0) :="0000000000000000";

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signal vert : STD_LOGIC_VECTOR (15 downto 0) :="0000001111100000";

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:

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:

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        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...

1

signal sspixcol : integer range 0 to 127 := 96;

2

signal sspixrow : integer range 0 to 63  := 32;

3

:

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:

5

        sspixrow <= sspixrow - 1;

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