PWM signal via sine-triangle comparison

Hi, thanks you two for your replies and your time !!

Hey FvM, the idea was to use natural sampling, how could i loose those pwm edges?

i checked my sine vector in modelsim and it really seems that i just have half a sine, buthow does this happen.

I thought when the variable x gets calculated its range is from 1 to -1 and this value is casted and stored in the vector?

I have the period of 20 ms in which i put 500 sine values. The triangular impulse has a period of 8µs.

So after 5 triangle impulses i need a new sine value.

So i have the countSine value run to 2000 and update the sinetabe

The compare function gets a new sine value every 5

Right now i dont know why i just didnt divide the sine in 5000 intervals seems much more

intuitive...

I post the complete code with some comments below:

Cheers

Tim

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
--use IEEE.STD_LOGIC_ARITH.ALL; --bad	
--use IEEE.STD_LOGIC_UNSIGNED.ALL;
use IEEE.STD_LOGIC_SIGNED.ALL;
use IEEE.NUMERIC_STD.all; --good  --to_unsigned to_signed  <- integer to ..
use ieee.math_real.all;
entity PWM is
    Port ( 
		CLOCK             : in  STD_LOGIC; 
		RESET             : in  STD_LOGIC;
		PWM_OUTPUT        : out STD_LOGIC
	     );
end PWM;  
architecture pwm_process of PWM is
	
SIGNAL Timer          	: integer range -2048 to 2047 := 0; 
SIGNAL countSine    		: integer range 0 to 4095 := 4095;
SIGNAL incSineTable		: integer range 0 to 500 := 500;
SIGNAL TimerDir        	: STD_LOGIC :='1'; 
SIGNAL SinValue			: std_logic_vector(8 downto 0) := (others =>'0'); 
type table is array (0 to 499) of std_logic_vector(8 downto 0);
function init_table return table is
	variable x: real;
	variable var: table;
	begin
		for i in 0 to 499 loop	
			x:= SIN(real(i)*MATH_PI/real(499));				
			var(i):=std_logic_vector(to_signed(INTEGER(x*real(100)),9));		
		end loop;	
	return var; 	 		 	 
end;
constant sinTable : table := init_table;
begin
---------------------------------------------------------------------------------
-------------------------Timer Direction Function--------------------------------
---------------------------------------------------------------------------------
--input clokc 50 MHz Timer counts to 200 -> 8µs period time 
TimerDirection:process (CLOCK,RESET,TimerDir,Timer)
begin     
	if  RESET = '0' then
		TimerDir <= '1';
	elsif CLOCK'event and CLOCK ='1' then     
		if (Timer =99) then 
			TimerDir <= '0'; 		
		end if;
		if	(Timer =-99) then               --1           
			TimerDir <= '1';
		end if;
	end if;
	--end if;
end process TimerDirection;
----------------------------------------------------------------------------------
--------------------------------Timer  counting-----------------------------------
----------------------------------------------------------------------------------           
CountingTimer: process (CLOCK,RESET,TimerDir,Timer)            
begin 
	if  RESET = '0' then
		--Timer<= (others => '0');
		Timer <= 0;
		
	elsif CLOCK'event and CLOCK ='1' then
		if (TimerDir ='1') then                       
			Timer <=Timer + 1;	
		end if;
		if (TimerDir ='0') then                          
			Timer <=Timer - 1; 
		end if;
		
	end if;
end process CountingTimer; 
---------------------------------------------------------------------------------
-------------------------------Update Sine Value --------------------------------
---------------------------------------------------------------------------------
-- Timer 2500 cycles in 20ms 500 sine values
-- every 5 cycles new sine value -> countSine to 2000
UpdateSineValue : process (CLOCK, RESET)
begin
	if RESET = '0' then
		incSineTable <= 0;
		countSine <= 0;
	elsif CLOCK'event and CLOCK ='1' then				
		SinValue <= sintable(incSineTable);
		if incSineTable = 500 then 
			incSineTable <= 0;
		end if; 
		countSine <= countSine +1;
			if	(countSine = 2000) then   
				incSineTable <= incSineTable +1;								
			end if;
	end if;
end process UpdateSineValue;
-------------------------------------------------------------------------------------
---------------------------- TimerCompare Function----------------------------
-------------------------------------------------------------------------------------             
TimerCompare: process (CLOCK,RESET,TimerDir,Timer)            
begin 
	if RESET = '0' then
		PWM_OUTPUT <= '1';				 
	elsif CLOCK'event and CLOCK ='1' then		
		--if (SinValue = to_signed(Timer,8))  and  (Timerdir<='1')then
		if SinValue = std_logic_vector(to_signed(Timer,9))  and  (Timerdir<='1')then		
			PWM_OUTPUT <= '0';
		end if;
		if SinValue = std_logic_vector(to_signed(Timer,9))  and  (Timerdir<='0')then 
			PWM_OUTPUT <= '1';
		end if;                                                                                  
	end if;                       
end process TimerCompare; 
 
end pwm_process;