FPGAWeek12Exercise

• Download the Frequency Counter and Frequency Generator reference designs from http://www.xilinx.com/products/boards/s3estarter/reference_designs.htm
• Download the Picoblaze processor core from http://www.xilinx.com/products/ipcenter/picoblaze-S3-V2-Pro.htm
• Unzip these projects & picoblaze source to your ~/Projects directory (or appropriatlely)
• Implementing the projects directly
  • Each project comes with a .bit file that you can use to program the FPGA starter kit with. Use impact to program the chip.
  • On Windows, you can run the install batch scripts to run impact automatically.
  • Find a buddy with a board, and each of you program your respective boards. Grab an SMA cable and use that to check the output of the generator with the counter.
• Implementing the projects through ISE
  • Implementing the frequency counter
    • In the frequency counter folder, there is a pdf. It is the readme for the project. It will be your friend - it details how to quickly run the project, setup the ISE project, design details for the hardware and picoblaze software, and some more project ideas.
    • In ISE, create a new design called "s3e_ref_freq_count" in your ~/Projects directory.
    • Add the existing .vhd and .ucf sources from the frequency counter reference design folder that you unzipped
    • Add the existing .vhd source for kcpsm3.vhd from the picoblaze VHDL source folder
    • A portion of the design uses a undocumented mode of operation for the S3E DCM. Instructions for enabling this can be found in the dcm_fixed_osc.vhd file. In my experience, this breaks P&R (-will), and this should be removed in order to complete the design. The DCM is simply working in an free-running oscillator mode; this is merely used to provide a frequency source for testing and its removal will not adversely affect the design.
      • You'll need to modify the frequency_counter.vhd file in the project, to remove the instance of 'dcm_fixed_osc.vhd' from the design. We won't be doing anything in-depth with VHDL so don't be intimidated by the different language syntax.
      • You'll want to comment out the component dcm_fixed_osc (approx line 117) . In VHDL, comments are done with double hypens, --.
      • Commented out component

--
-- Fixed frequency oscillator using a DCM
--
--component dcm_fixed_osc 
--  port(    clk_out : out std_logic;
--        kick_start : in std_logic   );
--  end component;  

• • • • The instantiation of the dcm_fixed_osc needs to be commented out (approximately line 223)
      • Commented portion

--  dcm_fixed_oscillator: dcm_fixed_osc
--  port map (    clk_out => dcm_oscillator,
--             kick_start => source_control(7) );

• • • • Now we'll need to change the multiplexer. To keep the design nearly intact, we'll replicate the ring oscillator signal twice (approx line 245).
      • Changed multiplexer

freq_for_measurement <= sma_clk when (source_control(1 downto 0)="00") 
                     else clk_50mhz when (source_control(1 downto 0)="01") 
                     else ring_oscillator when (source_control(1 downto 0)="10") 
                     else ring_oscillator;

• • • Select the top level module, and take it through the implementation process - synthesis, place and route, generate programming file.
    • Use impact to program the .bit file to the FPGA! It should
  • Implementing the frequency generator
    • In the frequency generator folder, there is a pdf. It is the readme for the project. It will be your friend - it details how to quickly run the project, setup the ISE project, design details for the hardware and picoblaze software, and some more project ideas.
    • In ISE, create a new design called "s3e_ref_freq_ref" in your ~/Projects directory.
    • Add the existing .vhd and .ucf sources from the frequency ref reference design folder that you unzipped
    • Add the existing .vhd source for kcpsm3.vhd from the picoblaze VHDL source folder
    • A portion of the design uses a undocumented mode of operation for the S3E DCM. Instructions for enabling this can be found on page 13 of the Frequency generator documentation.
    • Afer this is done, you should be able to implement this design and program the FPGA with impact.
• Things you can do!
  • You can use the .ucf file to move around the pin assignments. For instance, you can have the frequency counter read the clock input off of a stake or one of the pmod headers.3
  • Easy extension - create a second ring oscillator, called ring_osc2. You can extend the ring_osc.vhd for this purpose, adding additional delay stages will decrease the frequency generated. Follow a similar format, to the rest of the VHDL code, to declare the component, instantiation, a second ring_oscillator signal, and modify the multiplexer.
    • Once that is done, synthesis, P&R, and program the design. Select the second ring oscillator and see what its frequency is!
  • Look at the PDF's which come with the reference designs for more ideas!