====== Nexys 4 DDR Keyboard Demo ======

{{:nexys4-ddr:n4k.png?nolink&600|}}

===== Overview =====
<WRAP center round tip 80%>
The Nexys 4 DDR was rebranded as the Nexys A7 starting with Revision D starting in 2018. Updated releases of this particular demo project, usable by all versions of both the Nexys 4 DDR and the Nexys A7 can be found in the [[/programmable-logic/nexys-a7/start#example_projects|Nexys A7 Resource center]].
</WRAP>

==== Description ====

The Keyboard Demo project demonstrates a simple usage of the Nexys 4 DDR's 
USB-HID port and 7 segment display. The behavior is as follows:
 
 * The user presses a key on the keyboard, which sends a keyboard scan code to the Nexys 4 DDR. This scan code is read and output onto the 7 segment display. When a new scan code is read, it is shifted onto the 7 segment display from the right. A scan code of F0xx indicates that key xx has been released.

==== Features Used ====

| ^ Not Used ^ Used ^
^ 16 user switches                   |  X  |     |
^ 16 user LEDs                       |  X  |     |
^ Two tri-color LEDs                 |  X  |     |
^ 5 User Push Buttons                |  X  |     |
^ Two 4-digit 7-segment displays     |     |  X  |
^ 4 Pmod ports                       |  X  |     |
^ Pmod for XADC signals              |  X  |     |
^ 16-bit VGA output                  |  X  |     |
^ USB-UART Bridge                    |  X  |     |
^ Serial Flash for Application Data  |  X  |     |
^ USB HID Host With Mouse            |  X  |     |
^ USB HID Host With Keyboard         |     |  X  |
^ Micro SD card connector            |  X  |     |
^ PWM audio output                   |  X  |     |
^ PDM microphone                     |  X  |     |
^ 3-axis accelerometer               |  X  |     |
^ 128MiB DDR2                        |  X  |     |
^ Temperature sensor                 |  X  |     |
^ 10/100 Ethernet PHY                |  X  |     |
      
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===== Prerequisites =====

===Hardware===
  * **Nexys 4 DDR FPGA board**
  * **Micro-USB cable**
  * **USB Keyboard** 

===Software===
  * **Vivado Design Suite 2016.4** 
    * //Newer versions can be used, but the procedure may vary slightly//
  * **Nexys 4 DDR Support Files** 
    * These files will describe GPIO interfaces on your board and make it easier to select your FPGA board and add GPIO IP blocks. 
    * Follow the Wiki guide: [[vivado:boardfiles|Vivado Board Files for Digilent 7-Series FPGA Boards]] on how to install Board Support Files for 
-----

===== Downloads =====
Nexys 4 DDR Keyboard Project Repository -- [[https://github.com/Digilent/Nexys-4-DDR-Keyboard/releases/download/v2016.4-1/Nexys-4-DDR-Keyboard-2016.4-1.zip|ZIP Archive]] [[https://github.com/Digilent/Nexys-4-DDR-Keyboard|GIT Repo]]

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===== Download and Launch the Nexys 4 DDR Keyboard Demo =====

>1) Follow the [[:learn:programmable-logic:tutorials:github-demos:start|Using Digilent Github Demo Projects]] Tutorial. This is an HDL design project, and as such does not support Vivado SDK, select the tutorial options appropriate for a Vivado-only design. Return to this guide when prompted to check for extra hardware requirements and setup.

>2) Plug your USB Keyboard into the USB HOST port on your Nexys 4 DDR, then return to the Github Projects Tutorial to finish programming and running the demo.

===== Using the Nexys 4 DDR Keyboard Demo =====


==== 1. Initial State ====

>Initially, the 7 segment display will show all 0's
>
>{{:nexys4-ddr:img_20150310_192348.jpg?nolink&300|}}

==== 2. Key Press ====

>When a button is pressed, the value of the scan code will shift onto the 7 segment display. In the picture, 'a' is pressed, so a scan code of "1C" is displayed.
>
>{{:nexys4-ddr:img_20150310_192449.jpg?nolink&500|}}

==== 3. Key Release ====
  
>When the 'a' key is released, a scan code of "F01C" is shifted onto the 7 segment display. The initial scan code of "1C" is shifted to the left display.
>
>{{:nexys4-ddr:img_20150310_192501.jpg?nolink&500|}}

==== 4. Multiple Key Presses ====

>When multiple keys are pressed their scan codes are shifted in order. In this case, Q ("15") was pressed, followed by W ("1D").
>
>{{:nexys4-ddr:img_20150310_192533.jpg?nolink&500|}}

{{tag>learn programmable-logic project nexys-4-ddr}}