QModMaster — The Complete Guide: Free Testing of Modbus RTU and TCP Devices
QModMaster is a free graphical Modbus RTU and TCP master: read and write registers and coils on PLCs, meters, drives and sensors, with a bus monitor.
Guides and Articles
FidoCadJ — The Complete Guide: Quick Electrical and Electronic Drawings for Documentation
FidoCadJ is a very simple editor for electrical and electronic drawings that saves each sketch as compact text, easy to paste into forums, emails or docs.
VeroRoute — The Complete Guide: Stripboard and Perfboard Layout Without Short Circuits
VeroRoute lays out parts and tracks on stripboard, perfboard and simple PCBs, preventing shorts and catching open circuits as you work. Free, for prototypes.
TinyCAD — The Complete Guide: Simple Electrical and Electronic Schematics on Windows
TinyCAD is free Windows software for electrical and electronic schematics: symbol libraries, netlists for PCB tools and SPICE export. Light and stable.
Freerouting — The Complete Guide: Free Automatic PCB Routing for KiCad and Others
Freerouting is a free PCB autorouter: it takes a DSN file from KiCad or another tool, routes it and returns an SES file. How to use it, and when not to.
Horizon EDA — The Complete Guide: PCB Design With Disciplined Part Management
Horizon EDA treats board design as data management: a part is defined once with symbol, footprint and manufacturer number in one shared library.
gEDA — The Complete Guide: An Open Tool Suite for Schematics and Printed Circuit Boards
gEDA is a long-standing open-source electronics suite: schematic editor, netlister, symbol libraries and PCB layout. What it offers, and when to pick KiCad.
Electric VLSI — The Complete Guide: Open-Source Chip Layout and Schematic Design
Electric VLSI combines custom IC layout, schematic capture and DRC and LVS checks in one package, linked to external simulators. Free, for VLSI courses.
Digital — The Complete Guide: A Logic Simulator With Export to VHDL and Verilog
Digital lets you build a logic circuit on screen and run it: gates, flip-flops, memories, even a CPU, with truth tables, tests and VHDL/Verilog export.
GTKWave — The Complete Guide: Free Viewing and Analysis of Digital Simulation Waveforms
GTKWave opens VCD, FST and GHW files from simulators such as Icarus Verilog, Verilator and GHDL, and shows signals, buses and timing. Free and open source.
Icarus Verilog — The Complete Guide: A Small, Simple Verilog Simulator for Courses and Projects
Icarus Verilog compiles Verilog into a simulation you run from the command line, dumping waveforms for GTKWave. Small, quick to install, ideal for coursework.
Verilator — The Complete Guide: The Fastest Free Verilog and SystemVerilog Simulation
Verilator compiles synthesisable Verilog and SystemVerilog into a cycle-accurate C++ model that runs far faster than event-driven simulators. For CI and co-sim.