Engg Technical notes

1. Introduction to Sequential Logic Before we dive into memories and FSMs, we need to understand sequential logic . Combinational logic : output depends only on current inputs . Examples: adders, multiplexers, logic gates. Sequential logic : output depends on current inputs and previous state . Examples: flip-flops, registers, counters. Key Building Blocks: Flip-flops : Store a single bit of data. Types include D, T, JK flip-flops . Registers : Group of flip-flops storing multiple bits. Clock signal : Controls when sequential elements update their state. Why Sequential Logic Matters: Memories and FSMs are sequential circuits. Without understanding how data flows over time (clock cycles), modeling these components becomes impossible. 2. Memory Modeling in Verilog Memory in digital systems is simply a collection of registers or arrays of storage elements . 2.1. Memory Basics Memory Address : Unique location index (like 0, 1, 2, …). Memory Word : Data s...

1. Introduction In Verilog HDL (Hardware Description Language), designers frequently need to reuse code blocks, perform computations, or model specific behaviors. To achieve modularity and reduce repetitive coding, Verilog provides two procedural constructs: tasks and functions . While both tasks and functions encapsulate reusable code, they serve different purposes : Functions return a single value and execute in zero simulation time . They are ideal for combinational computations . Tasks can handle multiple outputs, include timing control statements (like # , @ , and wait ), and are used in sequential or complex behavioral modeling . This tutorial provides a detailed exploration of tasks and functions, their syntax, usage, examples, and best practices — equipping hardware designers and students to model and simulate Verilog designs effectively. 2. Understanding Tasks in Verilog A task is a procedural block in Verilog that encapsulates code which can be executed mu...

When we think of Verilog , most engineers picture RTL (Register Transfer Level) coding – writing always blocks, designing with if-else or case statements, and abstracting digital logic into behavioral or dataflow descriptions. However, Verilog also provides a lower-level way of modeling hardware, called Gate-Level Modeling . This is where you describe your circuits directly in terms of logic gates , switches , and transistor-level primitives . Even though gate-level coding is rarely used in RTL design , it plays a vital role after synthesis in ASIC and FPGA design flows . Let’s break it down. 🔑 Why Gate-Level Modeling Matters RTL Coding → Synthesis → Gate-Level Netlist In real chip design, RTL code is synthesized into logic gates . The synthesis tool generates a Verilog netlist made of gate primitives and standard cells . Gate-Level Simulation (GLS) This netlist is then simulated (often with back-annotated timing from an SDF file ) to check how the design behaves w...