Merge pull request #33 from saurabhb17/master

VHDL codes for PWM

3 files changed, 91 insertions, 0 deletions

diff --git a/Example/PWM/pwmdecrement.vhdl b/Example/PWM/pwmdecrement.vhdl
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+++ b/Example/PWM/pwmdecrement.vhdl
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+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+entity pwmdecrement is
+port(C : in std_logic;
+     D : in std_logic;
+     Q : out std_logic);
+end pwmdecrement;
+
+
+architecture bhv of pwmdecrement is
+        signal count: integer:=0;       
+        signal alpha: integer:=0;  --counts number of clocks
+        signal beta : integer:=1;  --counts number of times 'D' is low w.r.t Clock signal(C)  
+        signal tmp  : integer:=9; --stores the value of beta for which Q will be set HIGH
+        begin
+	process (C,D)
+
+        begin
+        if(C='1' and C'event) then
+        alpha<=alpha+1;  --counts number of rising edges
+                if(count=0) then --initial pulse 
+                Q <= '1';
+                count<=1;
+                end if;
+               if(D='0') then --if D is low, increase beta by 1
+                beta<=beta+1;
+                end if;
+                if(alpha=9) then --when aplha is 9, decrease beta by 1 and store in tmp //--set to 9 on purpose(so that first pwm signal has 90% duty cycle)
+                tmp<=beta-1; --decrease beta and store in tmp, so that we get 10% less duty cycle than previous
+                alpha<=0;
+                beta<=0;
+                count<=0;
+                end if;
+                if(tmp=alpha) then --the moment when number of clocks(alpha) equals previous number of times Q was high(tmp), we turn Q off. 
+                Q<='0';
+                end if;
+        end if;
+        end process;
+end bhv;
diff --git a/Example/PWM/pwmincrement.vhdl b/Example/PWM/pwmincrement.vhdl
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+++ b/Example/PWM/pwmincrement.vhdl
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+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+entity pwmincrement is
+port(C : in std_logic;
+     D : in std_logic;
+     Q : out std_logic);
+end pwmincrement;
+--working code for incrementing duty cycle \ Output of oscillator is fed back using a LPF and Comparator in F/B loop
+architecture bhv of pwmincrement is
+        signal count: integer:=0;       
+        signal alpha: integer:=0;  --counts number of clocks
+        signal beta : integer:=0;  --counts number of times 'D' is low w.r.t Clock signal(C) 
+        signal tmp  : integer:=0;  --stores the value of beta for which Q will be set HIGH
+        begin
+	process (C,D)
+
+        begin
+        if(C='1' and C'event) then
+        alpha<=alpha+1;  --counts number of rising edges
+                if(count=0) then --initial pulse 
+                Q <= '1';
+                count<=1;
+                end if;
+                if(D='0') then --if D is low, increase beta by 1
+                beta<=beta+1;
+                end if;
+                if(alpha=8) then --when aplha is 8, incremement beta by 1 and store in tmp //--set to 8 on purpose(so that first pwm signal has 10% duty cycle)
+                tmp<=beta+1; --increase beta and store in tmp, so that we get 10% more duty cycle than previous
+                alpha<=0; --reset alpha
+                beta<=0; --reset beta  
+                count<=0; --reset count
+                end if;
+                if(tmp=alpha) then --the moment when number of clocks(alpha) equals previous number of times Q was high(tmp), we turn Q off. Effectively incrementing duty cycle by 10%
+                Q<='0';
+                tmp<=0;
+                end if;
+        end if;
+        end process;
+end bhv;
diff --git a/Example/README.md b/Example/README.md
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+++ b/Example/README.md
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+Instructions on how to use the examples provided here:
+1. Go to eSim main window -> Click on NGHDL icon from the left toolbar, click on the 'browse' button, go to ../nghdl/Example/ and locate which example you wish to simulate.
+2. After opening the directory of desired example, locate the vhdl file , click on the "Open" button at the bottom of "Open File" window.
+3. Click on 'upload' button in the NGHDL pop-up window. File will be processed in the backend for few seconds. Now exit the NGHDL window.
+4. Open the desired example in eSim using the Open Project button, double click on it when the project is loaded in the "Projects" window.
+5. Click on the "Simulation" button on eSim Main window.
+
+NGHDL feature is still under development. More examples will be added by eSim team along the way.
+If you have a good command on VHDL and electronics, please feel free to contribute.