Introduction to FPGA Programming with Python Using MyHDL

Field-Programmable Gate Arrays (FPGAs) are powerful, reconfigurable hardware devices that can be programmed to perform specific tasks, offering immense flexibility and parallel processing capabilities. Traditionally, FPGA development is done using Hardware Description Languages (HDL) like Verilog or VHDL. However, as programming paradigms evolve, Python, a popular high-level programming language, has found its place in FPGA development through tools like MyHDL.

In this article, we will explore how to use Python and MyHDL to design FPGA systems, making it easier for developers familiar with Python to engage in hardware programming.
What is MyHDL?

MyHDL is an open-source Python package that allows developers to design and simulate digital hardware systems. It bridges the gap between traditional HDL and software programming by enabling users to write hardware designs in Python. Once the design is verified, MyHDL can convert it into Verilog or VHDL for synthesis onto an FPGA.

Key benefits of using MyHDL include:

High-level abstraction through Python.
Easier integration with other Python libraries and tools.
Faster iteration and testing cycles.
Seamless conversion to traditional HDL for FPGA deployment.

Why Use Python and MyHDL for FPGA Programming?

Familiar Syntax: Python is known for its clean and readable syntax, making it easier for software engineers to transition to hardware development.
Simulation and Testing: Python’s powerful libraries like NumPy, SciPy, and Matplotlib can be used alongside MyHDL for testing and simulation, greatly enhancing productivity.
Flexibility: MyHDL allows you to express your designs in Python, which can be more intuitive and flexible than traditional HDL.
HDL Conversion: After designing and simulating in Python, MyHDL allows conversion to Verilog or VHDL for synthesis, making it practical for real-world FPGA applications.

Setting Up the Environment

To get started with FPGA programming using Python and MyHDL, you need to set up your environment. Follow these steps:

Install Python: MyHDL works with Python, so ensure you have Python installed on your machine.

bash

sudo apt-get install python3

Install MyHDL: MyHDL can be installed using pip.

bash

pip install myhdl

Install FPGA Tools: Depending on your FPGA board, you will need the appropriate development software (e.g., Xilinx Vivado or Intel Quartus).

Example: Blinking LED Design

A common introductory example for FPGA design is creating a simple blinking LED. We will demonstrate how to implement this using Python and MyHDL.

python

from myhdl import block, always_seq, Signal, intbv

@block
def BlinkingLED(clk, led, reset, period):
count = Signal(intbv(0, min=0, max=period))

@always_seq(clk.posedge, reset=reset)
def logic():
    if count == period - 1:
        count.next = 0
        led.next = not led
    else:
        count.next = count + 1

return logic

Explanation:

clk: The clock signal.
led: The output signal to drive the LED.
reset: A signal to reset the design.
period: The time period for the LED blink cycle.

This Python code describes a simple digital circuit where the LED toggles its state every period clock cycles. After verifying the design through simulation, it can be converted into Verilog or VHDL for synthesis.
Simulating the Design

MyHDL allows you to simulate your design before converting it to hardware. Here’s how you can simulate the blinking LED design.

python

from myhdl import Simulation, delay, instance

def test_blinking_led():
clk = Signal(0)
led = Signal(0)
reset = Signal(0)
period = 10

led_blink = BlinkingLED(clk, led, reset, period)

@instance
def clk_gen():
    while True:
        clk.next = not clk
        yield delay(10)

sim = Simulation(led_blink, clk_gen)
sim.run(100)

test_blinking_led()

This testbench runs the simulation for 100 clock cycles, giving you insights into how the LED toggles based on the clock signal.
Converting to Verilog or VHDL

Once you are satisfied with your design and simulation, you can convert the Python code into a hardware description language. MyHDL provides built-in conversion functions for this.

python

from myhdl import toVerilog

toVerilog(BlinkingLED, clk, led, reset, period)

This generates a Verilog file that you can use with FPGA synthesis tools like Vivado or Quartus.
Conclusion

"If you need to purchase FPGAs, you can check out places like Bostock, but I won’t make any recommendations here.

Using Python and MyHDL for FPGA programming offers a unique combination of flexibility and accessibility, particularly for software developers who want to venture into hardware design. The ability to simulate, test, and convert designs into Verilog or VHDL makes MyHDL a powerful tool for FPGA development.

With this introduction, you are now equipped to explore the exciting world of FPGA programming using Python. Start experimenting with your own designs and take advantage of Python's simplicity to create complex digital systems!