Embedded Microcontroller – delabs

Analog devices like transistors and diodes lead to opamps and analog computing. This takes more parts but with fast devices can be real time. Then came Logic and Digital Circuits, here also big systems will take too many parts. A very Old hp Logic Analyzer instrument, could be HP1607A, had more than five large PCBs, Toggle Switches and numerous 74Fxx TTL Chips. I tried to revive it, it could not be fully restored.

Embedded Microcontroller – delabs

Then came the solution the Microprocessor. Here the entire system goes into the firmware and a Hardware Tool Set in the Microprocessor made up of Logic and Math is sequentially used to perform the same operation that would require innumerable Gates in a plain hardware digital circuit. But as it performs the operations one after another, it takes time and is defined by the CPU Clock Speed.

Embedded Microcontroller - delabs

When the External RAM and EPROM and other peripheral devices moved into the main package, MicroController were born. When more external devices merged with the MicroController. It formed a nearly complete computer, this is known as the SOC.

gEDA Project – Open Source EDA

The gEDA project is working on producing a full GPL’d suite of Electronic Design Automation tools. These tools are used for electrical circuit design, schematic capture, simulation, prototyping, and production.

gEDA – Electronic Design Automation

Currently, the gEDA project offers a mature suite of free software applications for electronics design, including schematic capture, attribute management, bill of materials (BOM) generation, netlisting into over 20 netlist formats, analog and digital simulation, and printed circuit board (PCB) layout.

gEDA Project’s Homepage

gEDA - Electronic Design Automation

gschem is the schematic capture program/tool which is part of gEDA. Its sole purpose is to facilitate the graphical input of components/circuits.

PCB is an interactive printed circuit board editor. PCB offers high end features such as an autorouter and trace optimizer which can tremendously reduce layout time. For custom requirements,


Icarus Verilog is a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code written in Verilog (IEEE-1364) into some target format. For batch simulation, the compiler can generate an intermediate form called vvp assembly.

GTKWave is a fully featured GTK+ based waveform viewer. GTKWave is designed to handle many signals at once, it has three signal searching modes (Regular Expressions, Hierarchy, and Tree) as well as the ability to display data in many different formats.

Resistors and How they Work

Resistors start from Wires to Wirewound Types. Carbon Film Resistors are most Common, Metal Film Resistors are more stable and accurate. We have now SMD types with lower power some are Laser Trimmed Types for accurate values. Resistors Arrays are used in Digital Circuits.

Types of Resistors – Color code and Other Resources

1/4 W Resistors have a Voltage rating of around 200-250V. Even when using a High value like 1 Meg use two in series when it is across Mains 230 V AC. 470K + 470K – you get around a Meg at 500V Rating.

Resistors and How they Work

Resistor 1/4W Metal Film
A standard range of 1/4W Metal Film Resistors suitable for most applications. High stability and solid construction ensure a long and stable life. 1% tolerance for the full range from 1R to 10M.

Riedon Resistors – Wirewound, Thick & Thin Film, and also Foil resistive elements.current sense, high pulse, high surge, surface mount, power and precision wirewound resistors.

High Performance Resistor Networks from Caddock – precision resistors, high voltage resistors, current sense resistors, chip resistors, high frequency resistors, and load resistors.

Ohmite’s Audio Gold resistors have been carefully engineered with non-magnetic materials to eliminate the effects of these stray magnetic fields on circuit performance. Ohmite’s LVC Series low value chip resistors are ideal for today’s current sense applications requiring low profile, low cost solutions

Control system design Notes

Proportional Controllers not only save energy, they can give a controlled finish or treatment to a job. An on-off controller or thermostat limit protection has to be used in series, this is to to stop a Runaway Process.

control system design

There was a real life instance when a Temperature cycling oven maker (environment chamber), faced large liabilities as an 8086 based profile controller and chart recorder just locked up and all the electronic equipment were roasted. Here even a bimetallic thermostat would have saved the day. Nowadays we have a watchdog timer to prevent such uP mishaps, but still use an analog controller in series as an over temperature trip.

Other Reading

The basics of control system design: Part 1 – Moving beyond PID

“This series of six articles will explore the use of six variations of P, I, and D gains: Proportional Control, Proportional-Integral Control, Psueodo-derivative feedback with feed-forwared (PDFF), PID control, PID+ control, and Proportional Derivative Control.”