Circuit Cellar Ink 267
October 2012

Table of Contents

2


CJ Abate

HTML Task Manager

Continuity of Content

10


CJ Abate

HTML New Product News

15


David Tweed

HTML Test Your EQ - Answers for Issue 266

16


Stuart Oliver

Math Routines Using dsPIC Features

Small embedded systems frequently require real-number math routines. Good performance and accuracy can be achieved at a low cost using small math routines and the dsPIC hardware features. This article describes some routines that use the accumulators and barrel shifter.

Download: 267-Oliver.zip

20


Richard Lord

Digital Camera Controller

Part 1: Hardware & Construction

The Photo-Pal is a microcontroller-based electronic flash-trigger camera controller that features four modes of operation: triggered shutter, triggered flash, multiple flash, and time lapse. Now you too can take sound-triggered photos.

Download: 267-Lord.zip

30


Kerry Imming

FAT Cache

Using File Allocation Table (FAT) Cache for Fast and Efficient SD Card Access

The FAT file system provides a convenient standard for data storage on SD flash memory cards. But that convenience comes with a performance penalty, since file system information must be accessed in addition to the file data. This article describes an algorithm that maximizes file data bandwidth by prefetching and compressing the file system information, virtually eliminating the file system overhead.

Download: 267-Imming.zip

The Consummate Engineer

34


George Novacek

Managing Project Risk

Risk is an integral, unavoidable part of project development. This article describes the process of defining and evaluating risk factors that could negatively impact project cost and delivery.

Embedded in Thin Slices

38


Bob Japenga

Concurrency in Embedded Systems

Part 3: Avoiding Concurrency Problems

The first two parts of this article series introduced concurrency in embedded systems and discussed two common concurrency design problems. The third part of this series examines generic ways to avoid some of these problems.

Above the Ground Plane

42


Ed Nisley

MOSFET Tester

Peltier Temperature Control and Results

Because semiconductor properties vary with temperature, a MOSFET tester must control the transistor's temperature. Ed's Arduino-based tester maintains a constant temperature using a linearized thermistor and a Peltier thermoelectric module. This column describes the temperature controller and presents some MOSFET characteristics over a 0C to 50C range.

Download: 267-Nisley.zip

The Darker Side

58


Robert Lacoste

Introduction to IIR Filters

Infinite impulse response (IIR) filters are feedback systems that use their outputs as inputs. It's easy to design a simple IIR filter and program it in your application if you know what tools to use. This article uses some simple math to provide the basics on IIR filters and explains the difference and similarities between IIR filters, finite impulse response (FIR) filters, and analog filters.

Download: 267-Lacoste.zip

From the Bench

68


Jeff Bachiochi

Mechanical Gyroscope Replacement

Part 1: A Microelectromechanical Systems (MEMS) Solution

A gyro uses internal circuitry to drive its masses into resonance, sample capacitive-coupled displacement sensors, and filter out unwanted artifacts. This article describes how a MEMS solution provides stability to a mechanical gyro. One sensor helps make up for the other's weaknesses when using a gyro, an accelerometer, and a magnetometer together.

76

Crossword Puzzle

79

Crossword Puzzle - Answers for Issue 266

80


Steve Ciarcia

HTML Priority Interrupt

Go Team!

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