FPGA Central

Hello All,

I have been simulating the FIFO code shown below with good success.
I have tested the behaviour under ModelSim waveform, where I send
three fifowren pulses, followed by three fiforden pulses, and a sequence
of numbers at the fifoin port, to determine if the right outputs pop off the
FIFO at the right time. I also test the FIFO in larger projects.

However. After generating Place and Route files, I ran the same
waveform testbed, same vectors, and got 0 outputs. No setup
warnings. What is wrong, or how do I find out what is wrong?

Thanks in Advance,

Brad Smallridge
b r a d @ a i v i s i o n . c o m


library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

library UNISIM;
use UNISIM.VComponents.all;

entity fifo36 is
port(
clk : in std_logic;
reset : in std_logic;
fifowren : in std_logic;
fiforden : in std_logic;
fifooe : in std_logic;
fifoin : in std_logic_vector(35 downto 0);
fifoout: out std_logic_vector(35 downto 0)
);
end fifo36;

architecture Behavioral of fifo36 is

component RAMB16_S36_S36

generic (
WRITE_MODE_A : string := "READ_FIRST";
WRITE_MODE_B : string := "READ_FIRST";
INIT_A : bit_vector := X"000000000";
SRVAL_A : bit_vector := X"000000000";
INIT_B : bit_vector := X"000000000";
SRVAL_B : bit_vector := X"000000000";

INITP_00 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INITP_01 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INITP_02 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INITP_03 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INITP_04 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INITP_05 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INITP_06 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INITP_07 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";

INIT_00 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_01 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_02 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_03 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_04 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_05 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_06 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_07 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_08 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_09 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_0A : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_0B : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_0C : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_0D : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_0E : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_0F : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_10 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_11 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_12 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_13 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_14 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_15 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_16 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_17 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_18 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_19 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_1A : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_1B : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_1C : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_1D : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_1E : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_1F : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_20 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_21 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_22 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_23 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_24 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_25 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_26 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_27 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_28 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_29 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_2A : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_2B : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_2C : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_2D : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_2E : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_2F : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_30 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_31 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_32 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_33 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_34 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_35 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_36 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_37 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_38 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_39 : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_3A : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_3B : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_3C : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_3D : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_3E : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000";
INIT_3F : bit_vector(255 downto 0) :=
X"000000000000000000000000000000000000000000000000 0000000000000000"

);

port (DIA : in STD_LOGIC_VECTOR (31 downto 0);
DIB : in STD_LOGIC_VECTOR (31 downto 0);
DIPA : in STD_LOGIC_VECTOR (3 downto 0);
DIPB : in STD_LOGIC_VECTOR (3 downto 0);
ENA : in STD_logic;
ENB : in STD_logic;
WEA : in STD_logic;
WEB : in STD_logic;
SSRA : in STD_logic;
SSRB : in STD_logic;
CLKA : in STD_logic;
CLKB : in STD_logic;
ADDRA : in STD_LOGIC_VECTOR (8 downto 0);
ADDRB : in STD_LOGIC_VECTOR (8 downto 0);
DOA : out STD_LOGIC_VECTOR (31 downto 0);
DOB : out STD_LOGIC_VECTOR (31 downto 0);
DOPA : out STD_LOGIC_VECTOR (3 downto 0);
DOPB : out STD_LOGIC_VECTOR (3 downto 0)
);
end component;

signal fifowraddr : std_logic_vector(8 downto 0);
signal fifordaddr : std_logic_vector(8 downto 0);

begin

bram00 : RAMB16_S36_S36
port map (
DIA => fifoin(31 downto 0),
DIB => (others=>'0'),
DIPA => fifoin(35 downto 32),
DIPB => (others=>'0'),
ENA => '1',
ENB => fifooe,
WEA => fifowren,
WEB => '0',
SSRA => '0',
SSRB => '0',
CLKA => clk,
CLKB => clk,
ADDRA => fifowraddr,
ADDRB => fifordaddr,
DOA => open,
DOB => fifoout(31 downto 0),
DOPA => open,
DOPB => fifoout(35 downto 32)
);

fifocnt: process(clk)
begin
if(clk'event and clk='1') then
if(reset='1') then
fifowraddr<=(others=>'0');
fifordaddr<=(others=>'0');
else
if(fifowren='1') then
fifowraddr<=fifowraddr+1;
end if;
if(fiforden='1') then
fifordaddr<=fifordaddr+1;
end if;
end if;
end if;
end process;


end Behavioral;

Brad Smallridge wrote:

> However. After generating Place and Route files, I ran the same
> waveform testbed, same vectors, and got 0 outputs. No setup
> warnings. What is wrong, or how do I find out what is wrong?

I don't use unisim, so I don't really know,
but you might start by removing the array initialization
code. There is no reason I know of to init fifo ram,
just the pointer registers.

Also consider inferring a block ram for the array:
http://groups-beta.google.com/groups...+fifo+ptr_type
Good luck

-- Mike Treseler

Yes, in this case there is no reason to initialize the BRAM, however,
I don't think that that is the reason the place and route simulation is
failing. I will try later today to replace the init 0s with init 1s, and
also
without inits.

You say you don't use unisim which seems to be the xilinx primitive
library. What are you using and why?

Brad Smallridge wrote:

> You say you don't use unisim which seems to be the xilinx primitive
> library. What are you using

I use code templates to infer block ram/rom.
My previous posting had an example.

> and why?

Simulation is simpler and faster and I
can target X, A or other devices.


-- Mike Treseler