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Summer of FPGAs - Building an Embedded System on FPGA

yesha98

Introduction:

Back then in February when I roadtested the USB104-A7, I had learned to create block designs using MicroBlaze. I found it very interesting but the available online resources were limited, the tutorials were based on the older versions of Vivado (Uploaded 6 years back or so). So I thought of making a course on using MicroBlaze in block designs and programming it with Xilinx SDK. Finally, after my semester exams were over, I got some free time to record the tutorials and the course material.

 

The course is designed in such a way that basic knowledge on FPGA programming using Vivado would be sufficient to take up this course. Also, the learner will understand the design of hardware while making the custom Pmod (Pmod Character LCD) and the working of Rotary Encoder.

 

Also, in this course, the design will be modified as new modules are added according to the requirements. The quadrature decoder module described in Verilog will also be added to the design at a later stage in the course. Thus, the learner will be able to feel the essence of the term "Reconfigurable Hardware".

 

Course Contents:

Video 1 - Introduction to MicroBlaze and AXI

Video 2 -- Lab 1 - Creating a block design with MicroBlaze and AXI GPIOs

Video 3 -- Lab 2 - Writing code in Xilinx SDK to interface with user LED and Pushbutton

Video 4 - Working of Character LCD and making of the Pmod LCD

Video 5 -- Lab 3 - Modifying the block design to interface Pmod LCD

Video 6 -- Lab 4 - LCD Driver Code to display elapsed seconds in LCD

Video 7 - Working of Rotary Encoder and Quadrature Decoder

VIdeo 8 -- Lab 5 - Adding the Quadrature Decoder Module to the Design

Video 9 -- Lab 6 - Writing code in SDK to display count and direction to the LCD

VIdeo 10 - Final Assessment

 

 

About the Course:

All videos are available on YouTube, here's the link to Playlist: https://www.youtube.com/playlist?list=PL6jYIySXv7VhUjg95oP88ubxRrr9MQMfH

Complete the final assessment to earn a certificate!

 

Course Overview:

 

Thanks for reading!

Anonymous
  • in reply to navadeepganeshu

    That's great! Yeah, it truly fascinates me when we can actually change the hardware which is not possible in the case of microcontrollers.

     

    The LCD is a bit problematic in the beginning because it's a bit hard to debug where the loose contact is, but eventually, you'll figure it out!

  • in reply to yesha98

    Works in charm! After this, I made the sw_in pin external and mapped the same to PIN2 of the Pmod by uncommenting and adding sw_in on the .xdc file.

    True. The real beauty is that now the hardware has got configured(quadrature decoder) with additional input switch parameter by what it seems like a software tweak(verilog file). Btw, Vivado is hiding a lot of stuff


    The LCD is showing up like this. Seems like a familiar loose contact issue in these type of parallel display interfaces. I'll check back the hardware wiring -- had rushed with the soldering process.

  • in reply to navadeepganeshu

    Oh yes. We need to modify the Quadrature Decoder hardware.

     

    module Quad_Decode (clk, rot_en_A, rot_en_B, direction, count, sw_in);

     

    input clk, rot_en_A, rot_en_B, sw_in;

    output reg direction;

    output [7:0] count;

     

    reg [2:0] rot_en_A_delayed, rot_en_B_delayed;

     

    always @(posedge clk)

    begin

    rot_en_A_delayed <= {rot_en_A_delayed[1:0], rot_en_A};

    end

     

    always @(posedge clk)

    begin

    rot_en_B_delayed <= {rot_en_B_delayed[1:0], rot_en_B};

    end

     

    wire count_enable = rot_en_A_delayed[1] ^ rot_en_A_delayed[2] ^ rot_en_B_delayed[1] ^ rot_en_B_delayed[2];

    wire count_direction = rot_en_A_delayed[1] ^ rot_en_B_delayed[2];

     

    reg [7:0] count;

     

    always @(posedge clk)

    begin

      if(count_enable)

      begin

        if(count_direction)

        begin

          direction <= 1;

          count <= count + 1;

        end

        else

        begin

          direction <= 0;

          count <= count - 1;

        end

      end

      else

       begin

         if (!sw_in)

         count <= 0;

      end

    end

     

    endmodule

     

    Connect the switch directly to the Quad_Decode module in block design.

    I guess this should do.

  • Again on Arty-S7, the rotary thing works fine the same way.

    I tried to add another parameter "Status" which would detect if the user presses the rotary encoder's central switch so as to set the value back to 0 at any point. So, added a new AXI_GPIO 1 bit wide to read SW pin of rotary encoder and took that parameter into the same while loop with if(status == 0). It was just a lame idea of trying to make it, I realized after running the program.

    The status does flip to 0 and so does the count. But when the switch is released, Status turns back to 1 as expected and counter resumes from the same point where it was before pressing that switch. Rather it was expected to start back from 0. So for this, would tweaking the quad_decode.v and adding in a new parameter to reset the full counter help? Any clues?

     

  • in reply to navadeepganeshu

    That's great ! I hope you'll enjoy the upcoming modules in the series too!