FPGA Intro Guide

The Pin Planner on Quartus Prime

This is a relatively straightforward guide to designing, building and programming an FPGA using the Quartus Prime Development Suite. This guide also includes an example Quartus Project, called Braindrop, that will be referred to throughout the guide.

Tools Used

Quartus Prime Standard Edition
ModelSim Simulation Tool
Qsys Systems Integration Tool
Intel Arria 10 GX Development Kit (Optional)

Preface

Think of a Field-Programmable Gate Array (FPGAs) as a processor whose physical logic you can code and design. Quite literally, what FPGA design tools like Quartus Prime do is to take a Hardware Description Language (HDL), such as Verilog or VHDL, and map it to physical digital logic onto a processor. This means, that given the time and resources, it is viable to program the logic of an x64 computer processor, such as the Intel i7, onto an FPGA. In fact, due to their versatility, FPGAs are largely used as test beds to prototype custom PCBs or chipsets.

Design Process

The design process for FPGA programming is straightforward:

Analysis & Synthesis
- This step compiles your HDL code, checking for syntax errors similar to a compiler.
Simulation
- Tools such as ModelSim can use waveforms as inputs to simulate and verify your logic
- If you do not have an FPGA, the following steps are unnecessary
Fitter (place & route)
- This step takes your HDL and physically maps it to the surface of the FPGA, using a series of digital logic gates
Assembler
- This step generates a programming file; in the case of Quartus, it generates a file with a .sof extension (SRAM object file)
- This programming file is what is interpreted by the hardware and is used primarily for hardware verification
Timing/Power Analysis
- These steps are optional; however, they give you insight into the efficiency & power consumption of your FPGA under different conditions

Quartus Prime Layout

The general layout for Quartus Prime is like any IDE. It includes a files tab on the left, displaying HDL files present in the directory. Additionally, it has a console on the bottom which continually displays log information relevant to the task at hand. As mentioned before, Quartus neatly encapsulates the FPGA design process into a list of todo items. During the compilation process, successfully completed tasks such as Analysis or Fitting get check-marked and logged into the console below.

For device specific design, it is essential to specify the product number of the FPGA that you are using. To change or setup your device, navigate to Assignments → Device.

Intel FPGA Naming Convention

Recall that the naming convention for Intel Arria 10 FPGAs is as follows:

Sample Project

The included sample project is called braindrop, it includes an HDL file called braindrop.v, which is a very simple Verilog program that activates a series of LEDs on the Intel Arria 10 GX based on user input. Even though this program is fairly low level, it does demonstrate the usage of fundamental CS principles in relation to FPGA Development

The important piece of braindrop.v involves its input and output parameters:

module braindrop (clk, IN0, IN1, LEDG, LEDR);
  input clk, IN0, IN1;     // clock typically from 10MHz to 50MHz
  output reg [7:0] LEDG, LEDR;

Pin Planning

Once the analysis & synthesis command has been executed, the pin planner in Quartus Prime automatically detects the variable names used and their respective functions.

In this screenshot, various pins have already been assigned. However, it is important for you to look through the documentation to determine which pins are available for use. In this case of the Intel Arria 10 GX, its documentation give the location of User defined I/O pins available for usage. Once these locations have been identifed, use the Pin Planner (Assignments → Pin Planner) to specifically define where on the FPGA certain pins will reside.

Quartus Prime Pin Planner

Running Waveform simulations

Waveform simulations are important tests to verify your verilog code in a setting where you either do not have an FPGA or need to verify your design in software.

Navigate to Tools → Run Simulation Tool → RTL Simulation

If you specified your RTL Simulation tool as ModelSim, then it should open. Expand the work directory and double click on your project name. Then, drag the objects you see into the "Wave" screen of ModelSim. Once there, you can right click on any of your inputs to simulate any waveform. In the following example, I have decided to simulate clock waveforms with a 50% and 25% duty cycle for IN0 and IN1 respectively

ModelSim Waveform Result

Hardware Verification

Once you have fully compiled your Quartus project and have a compatible FPGA, you are ready to run a hardware Verification

Plug your FPGA Development Kit into a power supply
Follow device specific instructions to enable user programming (in some cases, certain DIP switches need to be actuated)
Setup Interface with Dev Kit (JTAG, PCIe, or USB)
Open the Quartus Prime Programmer
- Click Hardware Setup to detect device configuration
- Next, detect your interface configuration on the programmer: Auto Detect → Finish
Add your .sof file to the top level device and enable Program/Configure
Click start to begin the programming process

arnav-gudibande/fpga-intro-guide