Circuit Cellar Ink 265
August 2012

Table of Contents

4


CJ Abate

HTML Task Manager

Embedded Systems Abound

10


CJ Abate

HTML New Product News

14

Member Profile: Mark Csele

15


David Tweed

HTML Test Your EQ - Answers for Issue 264

16


Mark Pedley

eCompass

Build and Calibrate a Tilt-Compensating Electronic Compass

A modern smartphone contains a built-in electronic compass (eCompass). How does the tilt compensation work, and how is the eCompass calibrated for the magnetic interference from the circuit board? This article describes how you can use the high-performance consumer accelerometers and magnetometers developed for the smartphone market to add a tilt-compensated eCompass to your own microcontroller project for less than $5.

Questions & Answers

24


Nan Price

The Man Behind the dsNavCon Design

An Interview with Guido Ottaviani

Guido Ottaviani worked as an analog and digital developer for several years for an Italian communications company. Today, he is a technical manager for a large Italian editorial group. In his spare time, Guido designs autonomous robots, shares his experiences with other self-professed "electronics addicts," and evangelizes robot design. In June, Guido and I discussed his fascination with robotics, his favorite microcontrollers, and some of his innovative projects, such as the dsNavCon system.

32


Scott Weber

MCU-Based Light Control

Longer Serial Communication on Differential Wires

You don't have to purchase expensive off-the-shelf home control equipment. For instance, you can use a microcontroller and a few other components to build a custom system to control lights on a predetermined schedule. This design is intended to replace a wall switch.

Download: 265-Weber.zip

40


Shlomo Engelberg

Examining an I/O Port

The Internal Structure of an I/O Pin with a Pull-Up Resistor

Understanding the internal workings of your microcontroller is essential. This article details how a simple experiment enables you to clearly "see" the structure of pins with internal pull-up resistors. The experiment also enables you to see the effect of each of the PMOS transistors that comprise the pull-up resistor.

Embedded in Thin Slices

44


Bob Japenga

Concurrency in Embedded Systems

Part 2: Atomicity and TOCTTOU

The first part of this article series introduced the topic of concurrency in embedded systems. This article discusses two common problems associated with embedded system designs containing concurrency: using nonatomic operation in concurrent threads and time of check to time of use (TOCTTOU).

The Consummate Engineer

48


George Novacek

Project Development

Part 2: Development Process, Milestones, and Design Reviews

A competent electronics engineer must conceptualize and then follow a proper project development plan. To do so, the engineer must understand the essential topics of development milestones, design reviews, and configuration control.

Above the Ground Plane

52


Ed Nisley

MOSFET Channel Resistance

Tester Hardware

Measuring MOSFET characteristics helps verify that the datasheet values will apply in an actual circuit. This Arduino-based tester applies known currents and voltages, and it sends the results to a PC for data logging and analysis. This article details the hardware design and verifies the overall calibration.

Download: 265-Nisley.zip

The Darker Side

58


Robert Lacoste

System-Level RF Design

Designing a radio frequency system -- even using precharacterized modules or components -- can be a daunting task without the proper methodology and tools. This article illustrates how system-level simulation tools can ease the process.

Download: 265-Lacoste.zip

From the Bench

68


Jeff Bachiochi

Charging with PV Cells

Energy harvesting is becoming more and more ubiquitous, but batteries -- including rechargeable batteries -- still play an important role in our day-to-day lives. This article discusses using photovoltaic (PV) cells, which are electrical devices that convert light's energy into electricity, as a means of keeping batteries charged.

76

Crossword Puzzle

79

Crossword Puzzle - Answers for Issue 264

80


Steve Ciarcia

HTML Priority Interrupt

What Were They Thinking?

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