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Altera_Forum's avatar
Altera_Forum
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9 years ago

Pseudo Random Bit Sequence Verilog

Hi,

I want to send a pseudo random bit sequence down a sfp+ port on my Stratix V fpga. Unfortunately I am unfamiliar with verilog. Can anyone help me with this or point me to the right resources? Thanks!

UPDATE: I managed to compile this code. How can I test to see if it is doing what I want (ex. can I print the bit sequence somewhere?)

module bit_generator(CLOCK_50, SFP);

input CLOCK_50;

output SFP;

reg [6:0]d;

always@(posedge CLOCK_50)

begin

d <= { d[5:0], d[6] ^ d[5] };

end

endmodule

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    9 years ago

    Typically you would simulate the module. So your simulation would have to drive the CLOCK_50 which if you google around you'll find plenty of examples of how to do that. You would add CLOCK_50, SFP, and maybe the d register to the simulator waveform views so that you can watch it behave over time.

  • Altera_Forum's avatar
    Altera_Forum
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    9 years ago

    Thanks for the reply. I prefer to test a physical implementation because I will be reusing the design of this basic implementation for testing an optical device. I've done some research and found that Quartus has megafunctions for instantiating SFP+ ports and the transceiver toolkit that automatically sends PRBS for BER testing. I have been trying to follow this example to get started: http://www.alterawiki.com/wiki/stratix_v_transceiver_phy_basic_design_examples

    But some of the code confuses me. Perhaps you can help me understand how to implement something similar?
  • Altera_Forum's avatar
    Altera_Forum
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    9 years ago

    I suspect there are also examples up on www.altera.com that cover the transceiver toolkit as well. Sorry I don't have any experience with transceivers so I don't know where to point you at. I think the PRBS pattern generation and checking might be implemented in the transceiver block so if you were looking for a code fragment for it you might not find it. If you want to see an example of a PRBS block you can take a look in the /ip directory in any of the zip files on this page: https://www.altera.com/support/support-resources/design-examples/soc/fpga-to-hps-bridges-design-example.html Those blocks might be overkill for what you are trying to do but they are programmable and can be setup by a system master like system console over JTAG, Nios II, HPS, etc...