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Contributor
Contributor
225 Views
Registered: ‎09-25-2017

Unable to generate square wave on FPGA Pin Output

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Hello Everyone,

I am trying to do a simple square wave generator.

I already test the code with success on a zybo board. The problem is now i changed the FPGA device to a Trenz FPGA (TE0820-3EG-1E), which has a ultrascale in it (the xczu3eg-sfvc784-1-e). I Verilog code for the generator is as follows:

`timescale 1 ns / 1 ps

module laser_control_v1_0
(
input clk_i,
input nrst_i,
//LASER CONTROL
//input laser_en_i,
output laser_o
//END OF LASER CONTROL
);

reg [8:0] laser_pulse_gen_r;
//reg laser_out_r;

always @(posedge clk_i or negedge nrst_i) begin
if(!nrst_i) begin
laser_pulse_gen_r <= 0;
end
else begin
laser_pulse_gen_r <= laser_pulse_gen_r + 1'b1;
end
end

assign laser_o = laser_pulse_gen_r[8];


endmodule

 

The problem is, I get nothing on the output. 

I already try the pin E2 and AF6 mapped to the laser_o output configured as LVCMOS18 but none of these pins work.

The clock signal is being generated by the ARM PLL (100MHz). In the simulation everything is fine and as I already said, the same code runs nice on a ZYBO development kit. 

Any ideas on what might be the problem?

 

Thanks in Advance

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1 Solution

Accepted Solutions
Contributor
Contributor
191 Views
Registered: ‎09-25-2017

Re: Unable to generate square wave on FPGA Pin Output

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Hi,

I figure out the problem. I was not initializing the PS properly and because of that the PLL was not generating the clock for my module.

Because my module only needs the PLL signal from the PS, I was testing it without starting my application program on the arm, and because of that the PS never initializes and thus no clock is generated on the output of the PS PLLs.

I just forgot that I had to run the application to initialize the PS, it was just a stupid mistake, sorry.

 

Best regards.

 

View solution in original post

2 Replies
Teacher drjohnsmith
Teacher
209 Views
Registered: ‎07-09-2009

Re: Unable to generate square wave on FPGA Pin Output

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So what does the simulation look like ?
try the post P&R simulation in particular
<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>
0 Kudos
Contributor
Contributor
192 Views
Registered: ‎09-25-2017

Re: Unable to generate square wave on FPGA Pin Output

Jump to solution

Hi,

I figure out the problem. I was not initializing the PS properly and because of that the PLL was not generating the clock for my module.

Because my module only needs the PLL signal from the PS, I was testing it without starting my application program on the arm, and because of that the PS never initializes and thus no clock is generated on the output of the PS PLLs.

I just forgot that I had to run the application to initialize the PS, it was just a stupid mistake, sorry.

 

Best regards.

 

View solution in original post