Hi all, I am a new to programming of VHDL to FPGA. Recently tried experimenting with a code from a book and during simulation, it was functioning perfectly. However after i programmed into Altera Cyclone IV EP4CE chip, the chip is always stuck at the default state regardless of the input. Was suspecting that the clock input is not configured properly thus i assigned the clock to Pin25 and yet it is not helping. Hope anyone can lend a helping hand to help troubleshoot.:(:confused: Thanks alot in advance. The code: LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_ARITH.ALL; USE IEEE.STD_LOGIC_UNSIGNED.ALL; ENTITY Traincollision IS PORT( reset, clock, sensor1, sensor2, sensor3, sensor4 : IN STD_LOGIC; switch1, switch2 : OUT STD_LOGIC; track1, track2, track3 : OUT STD_LOGIC; dirA, dirB : OUT STD_LOGIC_VECTOR( 1 DOWNTO 0 )); END Traincollision; ARCHITECTURE a OF Traincollision IS TYPE STATE_TYPE IS ( ABout, Ain, Bin, Astop, Bstop ); SIGNAL state: STATE_TYPE; SIGNAL sensor12, sensor13, sensor24 : STD_LOGIC_VECTOR(1 DOWNTO 0); BEGIN PROCESS ( reset, clock ) BEGIN IF reset = '1' THEN state <= ABout; ELSIF clock'EVENT AND clock = '1' THEN CASE state IS WHEN ABout => CASE Sensor12 IS WHEN "11" => state <= About; WHEN "10"=> state <= Bin; WHEN "01" => state <= Ain; WHEN "00"=> state <= Ain; WHEN OTHERS => state <= ABout; END CASE; WHEN Ain => CASE Sensor24 IS WHEN "11" => state <= Ain; WHEN "10" => state <= ABout; WHEN "01" => state <= Bstop; WHEN "00" => state <= ABout; WHEN OTHERS => state <= ABout; END CASE; WHEN Bin => CASE Sensor13 IS WHEN "11" => state <= Bin; WHEN "10" => state <= ABout; WHEN "01" => state <= Astop; WHEN "00" => state <= About; WHEN OTHERS => state <= ABout; END CASE; WHEN Astop => IF Sensor3 = '0' THEN state <= Ain; ELSE state <= Astop; END IF; WHEN Bstop => IF Sensor4 = '0' THEN state <= Bin; ELSE state <= Bstop; END IF; END CASE; END IF; END PROCESS; sensor12 <= sensor1 & sensor2; sensor13 <= sensor1 & sensor3; sensor24 <= sensor2 & sensor4; Track1 <='0'; WITH state SELECT Track3 <= '1' WHEN ABout, '1' WHEN Ain, '1' WHEN Bin, '1' WHEN Astop, '1' WHEN Bstop; WITH state SELECT Track2 <= '0' WHEN ABout, '0' WHEN Ain, '1' WHEN Bin, '1' WHEN Astop, '0' WHEN Bstop; WITH state SELECT Switch1 <= '0' WHEN ABout, '0' WHEN Ain, '1' WHEN Bin, '1' WHEN Astop, '0' WHEN Bstop; WITH state SELECT Switch2 <= '0' WHEN ABout, '0' WHEN Ain, '1' WHEN Bin, '1' WHEN Astop, '0' WHEN Bstop; WITH state SELECT DirA <= "01" WHEN ABout, "01" WHEN Ain, "01" WHEN Bin, "00" WHEN Astop, "01" WHEN Bstop; WITH state SELECT DirB <= "01" WHEN ABout, "01" WHEN Ain, "01" WHEN Bin, "01" WHEN Astop, "00" WHEN Bstop; END a;

Have you written a testbench for this code - have you simulated it>?

--- Quote Start --- Have you written a testbench for this code - have you simulated it>? --- Quote End --- Hi Tricky, Thanks for the reply. How do i go about writting a testbench for the code? Read up a few website but still clueless about it.:confused: And website that can help? Greatly appreciate ur help.

There are plenty of tutorial websites. A testbench is some VHDL code that stimulates your design under test. It doesnt have to be synthesisable and you can do plenty of "programming" like things. For example, to generate a clock, you can write: signal clk : std_logic := '0'; .... clk <= not clk after 5 ns; -- 100 Mhz clock

--- Quote Start --- There are plenty of tutorial websites. A testbench is some VHDL code that stimulates your design under test. It doesnt have to be synthesisable and you can do plenty of "programming" like things. For example, to generate a clock, you can write: signal clk : std_logic := '0'; .... clk <= not clk after 5 ns; -- 100 Mhz clock --- Quote End --- Geezz..Thanks! Having problem understanding the testbench thing. What is the difference between a testbench and simulation with waveform?

Assuming you're creating a waveform to drive a DUT (design under test), then your waveform IS your testbench. You run your testbench and DUT in a simulator and you can veiw the waveform in the wave window in the normal way. You need to use a proper simulator (like modelsim) to do HDL simulation. The quartus simulator is not very powerful and only simulates the compiled netlist via waveforms which is very slow compared to simulating the HDL directly. Another advantage of using HDL as the testbench is you can generate far more complex input stimulus, and output practically anything to text files.

Forum Discussion

Altera_Forum

Honored Contributor

10 years ago

Request for help in VHDL troubleshooting

Hi all,

I am a new to programming of VHDL to FPGA.

Recently tried experimenting with a code from a book and during simulation, it was functioning perfectly.

However after i programmed into Altera Cyclone IV EP4CE chip, the chip is always stuck at the default state regardless of the input.

Was suspecting that the clock input is not configured properly thus i assigned the clock to Pin25 and yet it is not helping.

Hope anyone can lend a helping hand to help troubleshoot.:(:confused:

Thanks alot in advance.

The code:

LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

USE IEEE.STD_LOGIC_ARITH.ALL;

USE IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY Traincollision IS

PORT( reset, clock, sensor1, sensor2,

sensor3, sensor4 : IN STD_LOGIC;

switch1, switch2 : OUT STD_LOGIC;

track1, track2, track3 : OUT STD_LOGIC;

dirA, dirB : OUT STD_LOGIC_VECTOR( 1 DOWNTO 0 ));

END Traincollision;

ARCHITECTURE a OF Traincollision IS

TYPE STATE_TYPE IS ( ABout, Ain, Bin, Astop, Bstop );

SIGNAL state: STATE_TYPE;

SIGNAL sensor12, sensor13, sensor24 : STD_LOGIC_VECTOR(1 DOWNTO 0);

BEGIN

PROCESS ( reset, clock )

BEGIN

IF reset = '1' THEN

state <= ABout;

ELSIF clock'EVENT AND clock = '1' THEN

CASE state IS

WHEN ABout =>

CASE Sensor12 IS

WHEN "11" => state <= About;

WHEN "10"=> state <= Bin;

WHEN "01" => state <= Ain;

WHEN "00"=> state <= Ain;

WHEN OTHERS => state <= ABout;

END CASE;

WHEN Ain =>

CASE Sensor24 IS

WHEN "11" => state <= Ain;

WHEN "10" => state <= ABout;

WHEN "01" => state <= Bstop;

WHEN "00" => state <= ABout;

WHEN OTHERS => state <= ABout;

END CASE;

WHEN Bin =>

CASE Sensor13 IS

WHEN "11" => state <= Bin;

WHEN "10" => state <= ABout;

WHEN "01" => state <= Astop;

WHEN "00" => state <= About;

WHEN OTHERS => state <= ABout;

END CASE;

WHEN Astop =>

IF Sensor3 = '0' THEN

state <= Ain;

ELSE

state <= Astop;

END IF;

WHEN Bstop =>

IF Sensor4 = '0' THEN

state <= Bin;

ELSE

state <= Bstop;

END IF;

END CASE;

END IF;

END PROCESS;

sensor12 <= sensor1 & sensor2;

sensor13 <= sensor1 & sensor3;

sensor24 <= sensor2 & sensor4;

Track1 <='0';

WITH state SELECT

Track3 <= '1' WHEN ABout,

'1' WHEN Ain,

'1' WHEN Bin,

'1' WHEN Astop,

'1' WHEN Bstop;

WITH state SELECT

Track2 <= '0' WHEN ABout,

'0' WHEN Ain,

'1' WHEN Bin,

'1' WHEN Astop,

'0' WHEN Bstop;

WITH state SELECT

Switch1 <= '0' WHEN ABout,

'0' WHEN Ain,

'1' WHEN Bin,

'1' WHEN Astop,

'0' WHEN Bstop;

WITH state SELECT

Switch2 <= '0' WHEN ABout,

'0' WHEN Ain,

'1' WHEN Bin,

'1' WHEN Astop,

'0' WHEN Bstop;

WITH state SELECT

DirA <= "01" WHEN ABout,

"01" WHEN Ain,

"01" WHEN Bin,

"00" WHEN Astop,

"01" WHEN Bstop;

WITH state SELECT

DirB <= "01" WHEN ABout,

"01" WHEN Ain,

"01" WHEN Bin,

"01" WHEN Astop,

"00" WHEN Bstop;

END a;

20 Replies

Altera_Forum
Honored Contributor
10 years ago
--- Quote Start ---
Your diagram shows that the reset signal is constant '1' - why?
--- Quote End ---

Hi tricky, good observation..
I have set it to active '0' instead..
Altera_Forum
Honored Contributor
10 years ago
Could you show us your new code? (put it between
and
tags to preserve formatting)
There seems to be some inconsistencies between the code and the signaltap screenshot.
Also you should start with a proper reset pulse before putting some signals on the sensors, to be sure you start in a correct state.

Altera_Forum

Honored Contributor

10 years ago

Hi there, sorry for the late reply.

Was tied up with work.

Below is the code for the program.

I tried signaltap on it and upon toggling the sensor 1/2, i was expecting it to enter into Ain/Bin state. But yet it seem to only trigger at the first try after reset. The subsequent tries has no response. Can help advise?

Thanks alot!

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.NUMERIC_STD.all;
ENTITY Tcontrol1 IS
PORT( reset, clock, sensor1, sensor2,
sensor3, sensor4 : IN STD_LOGIC;
switch1, switch2, switch1a, switch2a : OUT STD_LOGIC;
track1, track2, track3 : OUT STD_LOGIC;
dirA, dirB : OUT STD_LOGIC_VECTOR( 1 DOWNTO 0 ));
END Tcontrol1;
ARCHITECTURE a OF Tcontrol1 IS
TYPE STATE_TYPE IS ( ABout, Ain, Bin, Astop, Bstop );
SIGNAL state: STATE_TYPE;
SIGNAL sensor12, sensor13, sensor24 : STD_LOGIC_VECTOR(1 DOWNTO 0);
BEGIN
PROCESS ( reset, clock )
BEGIN
IF reset = '0' THEN
state <= ABout;
ELSIF clock'EVENT AND clock = '1' THEN
CASE state IS
WHEN ABout =>
CASE Sensor12 IS
WHEN "11" => state <= About;
WHEN "10"=> state <= Bin;
WHEN "01" => state <= Ain;
WHEN "00"=> state <= Ain;
WHEN OTHERS => state <= ABout;
END CASE;
WHEN Ain =>
CASE Sensor24 IS
WHEN "11" => state <= Ain;
WHEN "10" => state <= ABout;
WHEN "01" => state <= Bstop;
WHEN "00" => state <= ABout;
WHEN OTHERS => state <= ABout;
END CASE;
WHEN Bin =>
CASE Sensor13 IS
WHEN "11" => state <= Bin;
WHEN "10" => state <= ABout;
WHEN "01" => state <= Astop;
WHEN "00" => state <= About;
WHEN OTHERS => state <= ABout;
END CASE;
WHEN Astop =>
IF Sensor3 = '0' THEN
state <= Ain;
ELSE
state <= Astop;
END IF;
WHEN Bstop =>
IF Sensor4 = '0' THEN
state <= Bin;
ELSE
state <= Bstop;
END IF;
END CASE;
END IF;
END PROCESS;
sensor12 <= sensor1 & sensor2;
sensor13 <= sensor1 & sensor3;
sensor24 <= sensor2 & sensor4;
Track2 <='0';
WITH state SELECT
Track3 <= '0' WHEN ABout,
'0' WHEN Ain,
'0' WHEN Bin,
'0' WHEN Astop,
'1' WHEN Bstop;
WITH state SELECT
Track1 <= '0' WHEN ABout,
'0' WHEN Ain,
'0' WHEN Bin,
'1' WHEN Astop,
'0' WHEN Bstop;
WITH state SELECT
Switch1 <= '0' WHEN ABout,
'0' WHEN Ain,
'1' WHEN Bin,
'1' WHEN Astop,
'0' WHEN Bstop;
WITH state SELECT
Switch2 <= '0' WHEN ABout,
'0' WHEN Ain,
'1' WHEN Bin,
'1' WHEN Astop,
'0' WHEN Bstop;
WITH state SELECT
Switch1a <= '1' WHEN ABout,
'1' WHEN Ain,
'0' WHEN Bin,
'0' WHEN Astop,
'1' WHEN Bstop;
WITH state SELECT
Switch2a <= '1' WHEN ABout,
'1' WHEN Ain,
'0' WHEN Bin,
'0' WHEN Astop,
'1' WHEN Bstop;
WITH state SELECT
DirA <= "01" WHEN ABout,
"01" WHEN Ain,
"01" WHEN Bin,
"00" WHEN Astop,
"01" WHEN Bstop;
WITH state SELECT
DirB <= "01" WHEN ABout,
"01" WHEN Ain,
"01" WHEN Bin,
"01" WHEN Astop,
"00" WHEN Bstop;
END a;

Altera_Forum
Honored Contributor
10 years ago
have you got a testbench for this code, rather than trying to debug it on hardware (which takes much much longer)
Altera_Forum
Honored Contributor
10 years ago
--- Quote Start ---
have you got a testbench for this code, rather than trying to debug it on hardware (which takes much much longer)
--- Quote End ---

Hi Tricky,
Is this considered testbench?

Altera_Forum

Honored Contributor

10 years ago

it seems You should check sensor4 )

sensor24 <= sensor2 & sensor4

and

WHEN Ain =>
CASE Sensor24 IS
WHEN "11" => state <= Ain;
WHEN "10" => state <= ABout;
WHEN "01" => state <= Bstop;
WHEN "00" => state <= ABout;
WHEN OTHERS => state <= ABout;
END CASE;

Altera_Forum

Honored Contributor

10 years ago

--- Quote Start ---

it seems You should check sensor4 )

sensor24 <= sensor2 & sensor4

and

WHEN Ain =>
CASE Sensor24 IS
WHEN "11" => state <= Ain;
WHEN "10" => state <= ABout;
WHEN "01" => state <= Bstop;
WHEN "00" => state <= ABout;
WHEN OTHERS => state <= ABout;
END CASE;

--- Quote End ---

Hi Alex96,

Thanks for the pointers.

Mind sharing the concerns with sensor4?

Altera_Forum
Honored Contributor
10 years ago
--- Quote Start ---
Hi Tricky,
Is this considered testbench?
--- Quote End ---

No - this is a waveform from a simulator. How are you producing the waveform?

Altera_Forum

Honored Contributor

10 years ago

--- Quote Start ---

Hi there, sorry for the late reply.

Was tied up with work.

Below is the code for the program.

Thanks alot!

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.NUMERIC_STD.all;
ENTITY Tcontrol1 IS
PORT( reset, clock, sensor1, sensor2,
sensor3, sensor4 : IN STD_LOGIC;
switch1, switch2, switch1a, switch2a : OUT STD_LOGIC;
track1, track2, track3 : OUT STD_LOGIC;
dirA, dirB : OUT STD_LOGIC_VECTOR( 1 DOWNTO 0 ));
END Tcontrol1;
ARCHITECTURE a OF Tcontrol1 IS
TYPE STATE_TYPE IS ( ABout, Ain, Bin, Astop, Bstop );
SIGNAL state: STATE_TYPE;
SIGNAL sensor12, sensor13, sensor24 : STD_LOGIC_VECTOR(1 DOWNTO 0);
BEGIN
PROCESS ( reset, clock )
BEGIN
IF reset = '0' THEN
state <= ABout;
ELSIF clock'EVENT AND clock = '1' THEN
CASE state IS
WHEN ABout =>
CASE Sensor12 IS
WHEN "11" => state <= About;
WHEN "10"=> state <= Bin;
WHEN "01" => state <= Ain;
WHEN "00"=> state <= Ain;
WHEN OTHERS => state <= ABout;
END CASE;
WHEN Ain =>
CASE Sensor24 IS
WHEN "11" => state <= Ain;
WHEN "10" => state <= ABout;
WHEN "01" => state <= Bstop;
WHEN "00" => state <= ABout;
WHEN OTHERS => state <= ABout;
END CASE;
WHEN Bin =>
CASE Sensor13 IS
WHEN "11" => state <= Bin;
WHEN "10" => state <= ABout;
WHEN "01" => state <= Astop;
WHEN "00" => state <= About;
WHEN OTHERS => state <= ABout;
END CASE;
WHEN Astop =>
IF Sensor3 = '0' THEN
state <= Ain;
ELSE
state <= Astop;
END IF;
WHEN Bstop =>
IF Sensor4 = '0' THEN
state <= Bin;
ELSE
state <= Bstop;
END IF;
END CASE;
END IF;
END PROCESS;
sensor12 <= sensor1 & sensor2;
sensor13 <= sensor1 & sensor3;
sensor24 <= sensor2 & sensor4;
Track2 <='0';
WITH state SELECT
Track3 <= '0' WHEN ABout,
'0' WHEN Ain,
'0' WHEN Bin,
'0' WHEN Astop,
'1' WHEN Bstop;
WITH state SELECT
Track1 <= '0' WHEN ABout,
'0' WHEN Ain,
'0' WHEN Bin,
'1' WHEN Astop,
'0' WHEN Bstop;
WITH state SELECT
Switch1 <= '0' WHEN ABout,
'0' WHEN Ain,
'1' WHEN Bin,
'1' WHEN Astop,
'0' WHEN Bstop;
WITH state SELECT
Switch2 <= '0' WHEN ABout,
'0' WHEN Ain,
'1' WHEN Bin,
'1' WHEN Astop,
'0' WHEN Bstop;
WITH state SELECT
Switch1a <= '1' WHEN ABout,
'1' WHEN Ain,
'0' WHEN Bin,
'0' WHEN Astop,
'1' WHEN Bstop;
WITH state SELECT
Switch2a <= '1' WHEN ABout,
'1' WHEN Ain,
'0' WHEN Bin,
'0' WHEN Astop,
'1' WHEN Bstop;
WITH state SELECT
DirA <= "01" WHEN ABout,
"01" WHEN Ain,
"01" WHEN Bin,
"00" WHEN Astop,
"01" WHEN Bstop;
WITH state SELECT
DirB <= "01" WHEN ABout,
"01" WHEN Ain,
"01" WHEN Bin,
"01" WHEN Astop,
"00" WHEN Bstop;
END a;

--- Quote End ---

Forgot to add on that the sensor circuitry are active low.

When they are triggered, they goes low.

Altera_Forum
Honored Contributor
10 years ago
my Advice: after source will be compiled You should open RTLViewer and StateMachineViewer. Try to make analysis step-by-step. Then compare to your waveforms.

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Request for help in VHDL troubleshooting

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