Help me generate PWM in Verilog HDL

[Hafeez Anwar]

Hi,
I have a little problem in generating the PWM in verilog. Will any body help me or even give me a link on this topic

 

[sachingorkhe]

pwm verilog

PWM is the train of pulses with defined duty cycle.
Normally PWM having 10-90% duty cycle.
You can defined output as per required duty cycle and frequency to output with reference to input clock.

Regards,
Sachin

 

[Hafeez Anwar]

pwm verilog code

thankx a lot. but i wanna know that how can i use this wave to transmit my data which is used to be in binary format? and also how can i implement this idea in verilog? just help me in making the algo.

 

[sachingorkhe]

verilog pwm testbench

Here is a prog. which will generate the evenly distributed PWM signal. Use the following

module header
module pwm_even (duty,clk,oe,pwm_sig);
input [0:7] duty;
input clk,oe;
output pwm_sig;
tri pwm_sig;

where duty is the duty cycle, it is set using the 8 dip switches on board and can be varied from 0
to 255, for example, duty would equal 10, say clk is the on board 25MHz.
clock, oe is the tri-state output enable for pwm_sig (use active high enable), connect this to one of
the two pushbutton switches, and pwm_sig is the pulse width modulated signal.

HINT – This can be implemented using one counter, which is incremented in steps of duty at each clk (Trying to do a division, such as 256/10, is not the way to approach this problem).

Might be this will help you.

Sachin

 

[semesu]

fpga verilog pwm

Hi,
I have a project on pwm in verilog programming language. "pwm and one bit dac". The aim of this project is to convert the dıgıtal data to analog. Ihave found codes.
I am usıng xilinx spartan 3E kit

module PWM(clk, PWM_in, PWM_out);
input clk;
input [7:0] PWM_in;
output PWM_out;

reg [8:0] PWM_accumulator;
always @(posedge clk) PWM_accumulator <= PWM_accumulator[7:0] + PWM_in;

assign PWM_out = PWM_accumulator[8];
endmodule



but,in the codes a pwm accumulator is mentıoned and there ıs a command it is"PWM_accumulator <= PWM_accumulator[7:0] + PWM_in;" I don't understand why this command is written in the program and what is the functıon of the pwm accumulator?
my second questıon is how can I give an ınput to pwm ? can I use switches by making them on and off and can I create a dıgıtal data?
ıf there is anyone to help me,I will be glad.
thanks
regards

 

[semesu]

sigma delta pwm verilog

is there anyone help me?

 

[arikp]

verilog code for pwm

Hi ,

You can use an excel to simulate this. Simply this is doing a modulu of the input data (which is the PWM ratio) on an internal counter. The overflow (over 128) is the value of the PWM.

PWM CNTR INPUT VAL
0 0 70
0 70 70
1 140 70
1 210 70
0 24 70
0 94 70
1 164 70
1 234 70
0 48 70
0 118 70

.....

Arik P.

 

[FvM]

pwm in verilog

I think, the correct result is different:

out accu[7:0] in
0 0 70
0 70 70
0 140 70
0 210 70
1 24 70
0 94 70
0 164 70
0 234 70
1 48 70
0 118 70

The average output duty cyle is 70/256 = 0.27. This is basically a first-order sigma-delta modulator. Although the modulator is representing an analog value by a a duty cycle, I wouldn't designate it a PWM.

 

[semesu]

pwm using verilog

I can not understand exactly what you mean,can you explaın more clear?
thanks

 

[FvM]

pwm fpga verilog

Can you ask a clear question?

 

[semesu]

pwm en verilog

25 Dec 2008 15:52 Re: PWM in Verilog HDL


--------------------------------------------------------------------------------

I think, the correct result is different:

out accu[7:0] in // I don't understand the numbers below what are they for?
0 0 70
0 70 70
0 140 70
0 210 70
1 24 70
0 94 70
0 164 70
0 234 70
1 48 70
0 118 70

The average output duty cyle is 70/256 = 0.27. This is basically a first-order sigma-delta modulator. Although the modulator is representing an analog value by a a duty cycle, I wouldn't designate it a PWM.


Also,my project must be done by usıng pwm,so the sıgma-delta modulator is not useful for me I think,but I am not sure because I am not exper at verılog.yhis is my first project.

 

[FvM]

hdl pwm

Yes, I see. The basic difference is, that a sigma-delta modulator is intended to
shift all switching noise to high frequent spectral range, changing the switch output as fast as possible, while a PWM modulator produces a square wave with defined frequency. In my example, the PWM period is 256 clock periods, simply copying the signal resolution from the previous SD example. The PWM_out signal should be registered to avoid glitches.

module PWM(clk, PWM_in, PWM_out); 
input clk; 
input [7:0] PWM_in; 
output PWM_out;
reg PWM_out; 

reg [7:0] PWM_ramp; 
always @(posedge clk) 
begin
  PWM_ramp <= PWM_ramp + 1'b1; 
  PWM_out <= (PWM_in>PWM_ramp);
end
endmodule

 

[semesu]

pwm waveform in vhdl code

I have found new codes. I have sımulated it by moudle sımulator. and I get some results but I can nor understand whether they are rıght or not. can you help me to understand this?


module PWMMain(DC,CLK,Q);

input [7:0] DC;
input CLK;
output Q;
wire CLKO;
// synthesis attribute LOC clk "P9"
// synthesis attribute LOC Q "P1"
// synthesis attribute LOC DC "P11","P10","P7","P6","P5","P4","P3","P2"

//clkdiv div(CLK,CLKO);
PWM sev(DC,CLK,Q);

endmodule

module clkdiv(CLKIN,CLKOUT);
input CLKIN;
output CLKOUT;

wire iclk;
parameter BITS=13;
reg [BITS-1:0] COUNT;
initial COUNT=0;
assign CLKOUT=COUNT[BITS-1];
BUFG clkbuf(iclk,CLKIN);
always @(posedge iclk)
begin

COUNT = COUNT + 1;
end
endmodule



module PWM(DC,CLK,Q);
input [7:0] DC; // duty cycle input
input CLK;

output Q;
reg [8:0] acc; // accumulator has one more bit than the duty cycle
assign Q=acc[8]; // output is the 8th bit

initial acc=0; // for simulation only
always @(posedge CLK)
begin

acc=acc[7:0]+DC; // only add with 8 bits.
end
endmodule

testbench is below


module denemee;


reg [7:0] DC;
reg CLK;

// Outputs
wire Q;

// Instantiate the Unit Under Test (UUT)
PWMMain uut (
.DC(DC),
.CLK(CLK),
.Q(Q)
);


always
begin
CLK = 1;
#0.1;
CLK = 0;
#0.1;
end




the ouıtput of thıs stımulus,does it give the right output?
please help me...
thanks

 

[FvM]

duty cycle of pwm verilog

It's also SD code.