Bus direction

[john]

Hello,

I have interfaced a USB2.0 chip to a CPLD. The CPLD also has an 19 bit
counter. At the powerup, CPLD sometimes reset 19 bit counter and
sometimes do not reset its 19 bit counter. when I removed the USB bus
then CPLD resets its 19 bit counter perfectly.

Please advice to remove this problem.

Thanks
John

 

[Mike Treseler]

Please advice to remove this problem.

Write a testbench. Run a simulation. Edit code.

-- Mike Treseler

 

[ALuPin]

How do you reset the counter ?
Some code ?

Rgds
André

 

[tatto0_2000]

How do you reset the counter ?

Normally we have a 'Global' reset for all the logic. The reset will
sets all to a 'default' state.

Some code ?

I think it could be easily obtained somewhere ....

 

[vizziee]

Some code ?

here is the sequential code:

process (reset,...other inputs...)
begin
if (reset = '1') then --asynchronous reset
count_out <= (others => '0');
elsif clk'event and clk = '1' then --rising edge
if (sync_reset = '1') then --synchronous reset
count_out <= (others => '0');
else
-- ur counter logic --
end if;
end if;
end process;

 

[john]

Hello,

Thanks for ur reply! The problem is that I do not have "synch_reset"
pin in my design. I posted my code under topic "Initialization" at VHDL
group. would u please take a look at it! would you advice to include
this signal as an external pin or a signal controlled by the state
machine.
My code is given below

Entity DPR is


port (


Data_Bus ut unsigned (13 downto 0 );
Address_bus : inout unsigned (18 downto 0 );
Read_write: out std_logic;
Output_Enable : out std_logic;
DPR_CLK : in std_logic;
CE0: out std_logic;
CE1 ut std_logic;
LBL ut std_logic;
UBL out std_logic;
USB_Data :in unsigned (7 downto 0 );
USB_CLK :in std_logic;
output_signal : out std_logic;
ZZL: out std_logic:='0';
SEML: out std_logic:='1';
OPTL : in std_logic;
Async_RESET: in std_logic
);


End DPR;


Architecture DPR_ARCH of DPR IS


signal State2: unsigned(1 downto 0);
signal nextstate2: unsigned(1 downto 0);


constant G0 : unsigned(1 downto 0):="00";
constant G1 unsigned(1 downto 0):="01";
constant G2 : unsigned(1 downto 0):="10";
constant G3 : unsigned(1 downto 0):="11";


Signal inc: std_logic;
Signal Reset_A: std_logic;
Signal State1,nextstate1: integer := 0;
Signal sec_stop: std_logic;
Signal sec_counter: unsigned ( 18 downto 0);


Begin


output_signal <= sec_stop;
CE0 <= '0';
CE1 <= '1';
Output_Enable <= '1';
Read_write <= '0';
Address_bus <= sec_counter;


Process (State2 )
Begin


Case State2 is


When G0=>
inc <='0';
Data_Bus ( 13 downto 8) <= USB_Data ( 5 downto 0 );
UBL <='0'; --1 old value
LBL <='0'; --0 0ld value


nextstate2 <=G1;


When G1 =>
inc <='0';
Data_Bus ( 7 downto 0) <= USB_Data ( 7 downto 0 );
UBL <='0'; --0 old value
LBL <='0'; --1 old value


nextstate2 <=G2;


When G2 =>
inc <='1';
Data_Bus ( 13 downto 8) <= USB_Data ( 5 downto 0 );
UBL <='0';
LBL <='0';
nextstate2 <=G3;


When G3 =>
inc <='0';
Data_Bus ( 7 downto 0) <= USB_Data ( 7 downto 0 );
UBL <='0';
LBL <='0';


nextstate2 <=G2;
When others =>


nextstate2 <=G0;


End case;
End Process;


Process (USB_CLK ,Async_RESET)
Begin


If ( Async_RESET = '0') Then


sec_counter <= "0000000000000000000";
State2 <= G0;


Else If (USB_CLK 'Event And USB_CLK = '0') Then


State2 <= nextstate2;


If ( sec_counter (18)='0' and sec_counter(17)='0' and
sec_counter(16)='0' and sec_counter(15)='0' and
sec_counter(14)='0' and sec_counter(13)='1' and
sec_counter(12)='0' and sec_counter(11)='0' and
sec_counter(10)='1' and sec_counter(9)= '0' and sec_counter(8)=

'0' and sec_counter(7)='0' and sec_counter (6) ='0' and
sec_counter(5)= '1' and sec_counter(4)='0' and
sec_counter(3)= '0' and sec_counter(2)= '0' and
sec_counter(1)='0' and sec_counter(0)= '0')
Then


sec_stop <= '1';
State2 <= G0;


Else
sec_stop <= '0';


End If;


If (inc = '1' AND sec_stop = '0' ) Then


sec_counter <= sec_counter + 1 ;
Else


End If;


End If;


If ( USB_CLK 'Event And USB_CLK = '0')Then


If ( sec_stop= '1' ) Then


sec_counter <= "0000000000000000000";


Else


End If;


End If;


End If;


End Process;
End DPR_ARCH;

Thanks
Regards
John