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Altera_Forum
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Honored ContributorVHDL robot design not working
Hello everybody I'm new in VHDL and I'm doing a project with DE2 board
In the project I need to build a robot. My first step was to design a ASM and from that to take out the FSM which i did (hopefully I did it good enough) The second step is to check one of my ASM and I choose my engine control ASM I wrote a program in VHDL using quartus and burn it into my board Instead of using the motors from the beginnig the idea was to used the board's led using a PWM generator that will create a "running led" effect for a curtain direction and in change it in a push of a button but it didn't work. Can anybody tell me what I did wrong? I think it's in the pin assignment34 Replies
Altera_Forumwow thanks,
That should be very helpful I have tests coming up this week I'll let you know who I managed to fix the code later on- Altera_Forum
To make LED connect to RD_LED, just assign it outside of a process. Or if you want to make it a variable, just assign LED above if counter = 50000 then.., and asign RD_led (as a variable) where it is now. Variables can store values between clocks if you put things in the right order.
For DC, because it is set a value and nothing else, Quartus will probably just assume it is a constant. But making it a generic might be a good idea. Generics are created like ports, in the generic section:
Then when you do the instantiation, you give it a value.entity my_ent is generic ( DC : integer; ); port ( ); end entity my_ent;
Inside your entity, you just treat generics like constants.my_inst : entity work.my_ent generic map ( DC => 32678, ) port map ( ... ); - Altera_Forum
your right I should have know that...
that kind of relate to a another problem I notice, if I have a lag and I want to get ride of it I need to change Rd_Led to a variable but then his value want be save after he loop right? so what can I do?. second problem is about DC it's a lacth and can't work in a real board. I need to change it to a constant, but I want it to be more general code so I'll change it to a generic , were and who do I create a generic (entity, architecture ..)? - Altera_Forum--- Quote Start --- I don't know what you mean when you say that the Led lag the rd_led they update together they are in the same IF Statement suppose to be any way that who I see it . --- Quote End --- Because you assign LED to rd_LED, LED takes the old value of rd_LED. Signals are not updated immediatly like variables, they are updated when a process suspends. so whith this code in a clocked process: b <= a; c <= b; this is what happens:
clk _|-|_|-|_|-|_|-|_|-|_| a 0 1 2 3 4 5 b U 0 1 2 3 4 c U U 0 1 2 3 - Altera_Forum
I wanted that the led will light in 1khz so I could see them.
so if DE2 board have 50Mhz clock I need to count to 50000. taking that into account if every cycle I raise the output Led only once it means that the led change once per 0.5ms that means twice in 1khz cycle just like you said and what I wanted it to do. once and let say I want it to run at least 50 times so I need 50ms delay so far I hope I got it right. I don't know what you mean when you say that the Led lag the rd_led they update together they are in the same IF Statement suppose to be any way that who I see it . if the code is good at least reasonable enough to work maybe I just dont know who to run the sim and a guide will help? - Altera_Forum
Plus also the LED output lags the rd counter by 50000 clocks.
- Altera_Forum
Maybe you do mean ms. The rd_led counter only increments once every 50000 clock cycles (thats once every 500 us) so 1ms increments the counter twice
- Altera_Forum
I see the Rst problem now and it was supposeto be ns and ms... but still no waves?
library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_arith.all; use ieee.std_logic_unsigned.all; --use std.textio.all; --use ieee.std_logic_textio.all; ------------------------------------------------------------------------------ entity tb_pwm is end entity tb_pwm; ------------------------------------------------------------------------------ architecture arc_tb_pwm of tb_pwm is signal Clk : std_logic := '0'; -- signal Rst : std_logic := '0'; -- signal Sw : std_logic_vector (2 downto 0):= "000"; -- signal Enable : std_logic := '0'; -- signal Pwm : std_logic; -- signal Led : std_logic_vector(7 downto 0); -- begin test : entity work.pwm port map ( Clk => Clk, Rst => Rst, Enable => Enable, Sw => Sw, Pwm => Pwm, Led => Led ); Clk <= not Clk after 10 ns; process begin wait until rising_edge(Clk); Enable <= '1'; wait until rising_edge(clk); Sw(0) <= '1'; Sw(1) <= '0'; Sw(2) <= '0'; wait until rising_edge(clk); Sw(0) <= '0'; Sw(1) <= '1'; Sw(2) <= '0'; wait for 0.1us; wait until rising_edge(clk); Sw(0) <= '0'; Sw(1) <= '0'; Sw(2) <= '1'; wait for 0.1us; wait until rising_edge(clk); Enable <= '0'; wait for 0.1us; wait until rising_edge(clk); wait for 0.1us; Rst<= '0'; end process; end architecture arc_tb_pwm; - Altera_Forum
The problem is your reset it driven outside and inside the process, leading to rst beign 'X', and none of the internal counters get initialised to 0. Either remove the rst <= after 20ns; line or Rst <= '0' inside the process.
Signals can only be driven from one place. Secondly - are you sure you meant wait for 100ms? that is 10 million clocks with the clock period you have chosen. thirdly, you are holding the design in reset for the whole simulation. numeric_std is the official IEEE standard library. std_logic_arith/unsigned are not a real standard, but they allow you to do maths on std_logic_vectors. std_logic_vectors were NOT meant to represent an integer, just a collection of bits. numeric_std contains an unsigned and signed type that do represent numbers. you cannot use numeric_std and std_logic_arith in the same file as they contain clashes. - Altera_Forum
Your right I changed the code a little.
I am don't know what numeric std library does can you clarify please, and why is it better to use rather then std_logic in general and specific in this codelibrary IEEE; use IEEE.std_logic_1164.all; use ieee.std_logic_arith.all; use ieee.std_logic_unsigned.all; use ieee.numeric_std.all; Entity Pwm is Port ( Rst : In std_logic; Clk : In std_logic; Sw : In std_logic_vector (2 downto 0); Enable : in std_logic; Led : out std_logic_vector (7 downto 0); Pwm : Out std_logic); attribute altera_chip_pin_lc: string; attribute altera_chip_pin_lc of Clk : signal is "@N2"; attribute altera_chip_pin_lc of Rst : signal is "@G26"; attribute altera_chip_pin_lc of Led : signal is "@AE23, @AF23, @AB21, @AC22, @AD22, @AD23, @AD21, @AC21"; attribute altera_chip_pin_lc of Sw : signal is "@N25,@N26, @P25"; attribute altera_chip_pin_lc of Enable: signal is "@AE14"; end entity Pwm; Architecture arc_Pwm of Pwm is signal Counter : std_logic_vector (16 downto 0); signal DC : std_logic_vector (16 downto 0); signal Rd_led : std_logic_vector (7 downto 0); begin PwmReg: process (Clk,Rst,Sw) begin if (Rst='1') then Counter <= (others=>'0'); Pwm <='0'; Led <= (others=>'0'); Rd_led <= (others=>'0'); DC <= conv_std_logic_vector(32678,17); --duty cycle 50% elsif rising_edge(Clk) then if (Enable='1') then if (Counter = 50000) then Counter <= (others => '0'); if (Sw(0) = '1') and (Sw(1) = '0') and (Sw(2) = '0') then Rd_led <= Rd_led + 1; elsif (Sw(0) = '0') and (Sw(1) = '1') and (Sw(2) = '0') then Rd_led <= Rd_led - 1; end if; Led <= Rd_led; elsif (Counter < DC) then Counter <= Counter + 1; Pwm <= '1'; else Counter <= Counter + 1; Pwm <= '0'; end if; else Pwm <= '0'; end if; end if; end process PwmReg; end architecture arc_Pwm;
