Julian Ferry - EEWeb

Julian 

Ferry 

High Speed Engineering 

Manager, Samtec 

FEATURED PROJECT 

Raspberry Pi - 

Part 2 

TECHNICAL ARTICLE 

Facing the 

Counterfeit 

IC Issue 

EEWeb 

Issue 90 

March 19, 2013 

Electrical Engineering Community eeweb.com

EEWeb PULSE TABLE OF CONTENTS 

Julian Ferry 

HIGH SPEED ENGINEERING MANAGER AT SAMTEC 

A conversation with Samtec’s High Speed Engineering Manager about its differentiated 

connectors as well as some tips for choosing the right connector for your application. 

Featured Products 

Facing the Counterfeit IC Problem 

BY ALAN LOWNE WITH SAELIG 

“Fake” chips in the marketplace is a huge issue for manufacturing companies and distributers 

alike. Here is a solution to that problem. 

Picking Components With Confidence 

BY TAMARA SCHMITZ WITH INTERSIL 

The daunting task of selecting the right components for your project made easy. 

The Raspberry Pi - Part 2: Raspbian Wheezy 

& Arch Linux ARM 

BY KYLE OLIVE 

The second installment of this series outlines two different popular operating systems for the 

Raspberry Pi, Arch Linux ARM and Raspbian Wheezy. 

RTZ - Return to Zero Comic 

Visit www.eeweb.com 

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30 

3

EEWeb PULSE INTERVIEW 

Julian 

Ferry 

Samtec is a service leader in the electronic interconnect 

industry. Its emphasis on customer satisfaction and service 

mixed with quality products solidifies its multinational 

status. We spoke with Julian Ferry, the High Speed Engineering 

Manager at Samtec, about why customer 

service is key, how Samtec differntiates itself from 

other connector companies, and a few tips for 

choosing the right connector for your application. 

4 EEWeb | Electrical Engineering Community 


5


How did you get into Electrical 

Engineering? 

I was always tearing stuff apart when 

I was a kid, and I eventually taught 

myself how to solder. I built antennas 

and fixed radios and amplifiers and 

stuff. When I was 16 or 17, I pulled an 

old oscilloscope out of the trash and 

fixed it up. I just thought it was fun. 

I didn’t think this interest might have 

some value in the real world. 

I went to Penn State in the mid 

1980’s, and started out as a chemical 

engineering major. I had some good 

chemistry and biology teachers 

in high school, and I think that 

influenced me at the time. But I did 

have some people telling me I should 

consider electronics. I switched 

majors to EE after my first Physics 

Electromagnetics class. Something 

just clicked. After that, I focused 

on Microwave and RF Design and 

Communications and took a lot of 

electives in those areas. 

When I graduated, I started to work at 

what was then AMP Inc., which is now 

part of TE Connectivity and the former 

Tyco. They were the world’s largest 

connector company at the time. I 

worked in a product qualification test 

lab in a group that did microwave and 

RF testing of connectors and cables. 

Network Analyzers (VNA’s) had just 

made it into that industry, and we were 

testing to 26 GHz. This was also when 

high-speed computer designers were 

starting to run into microwave-like 

problems in their digital systems. 

Early in my career, I got involved 

in time domain and signal integrity 

work. One of my first projects as a test 

engineer was to build a differential 

TDR system, because they weren’t 

commercially available. 

Later at AMP, I moved into a product 

development group where I focused 

on telecomm and data products, and 

eventually on Cat-5-type cabling 

products. This was a combination 

mechanical and electrical 

engineering role, and I learned a lot 

of new skills there. I participated in 

developing the Cat-5 spec, which 

covers building wiring products for 

both data and telecom, and that was 

very educational. Around 1993, 6 or 

7 years in to my career, I moved into 

a management role, which was way 

ahead of my planned timeline. But it 

worked out OK, and I eventually built 

up a test lab and EE design team 

of 6 engineers. I later moved into a 

pure R&D group in a Technical Staff 

role, where I focused on improving 

connector modeling and simulations. 

At the time we were moving from 2D 

field solvers, which had been the 

standard tool for 10-15 years, to 3D 

solvers. 

From there, I worked a few years 

at Foxconn, where I designed 

high-speed cable assemblies and 

connectors. While I was at Foxconn, 

I got a call from Samtec. I knew 

Samtec didn’t offer many highspeed 

products—they were more 

focused on pin-headers and similar 

connectors. But they were branching 

out into smaller, tighter pitch, SMT 

type connectors. Signal speeds 

were also increasing rapidly, and the 

combination of higher signal density 

and increased data rates was starting 

to make signal integrity problems 

more widespread. They were getting 

customer requests for things like 

SPICE models and insertion loss and 

crosstalk data, and they didn’t know 

how to respond. 

At that point, Samtec was mostly 

mechanical engineering focused. 

They used consultants to help 

them with SI problems, but they 

realized they needed signal integrity 

engineers on staff, not only to help 

design high-speed products, but also 

to help their customers. Best-in-class 

customer support has always been a 

goal for Samtec. At the time (around 

2000), signal integrity support was 

lacking in the connector industry. 

Samtec had decided to open an 

office near Harrisburg, PA, because 

of the number of SI connector 

engineers in the area, along with 

other local connector expertise. 

“When we started our 

group, most companies 

were providing good 

support to what we would 

call Tier 1 companies, 

but they would pretty 

much ignore the smaller 

businesses. At Samtec, 

those smaller companies 

are a focus for us.” 

AMP had been headquartered in 

the area since the 1940’s, and many 

support industries had grown in the 

area. There were about 60 different 

connector manufactures located near 

Harrisburg. I was the first EE hired 

by Samtec, and part of my job was to 

build an SI engineering team. We’re 

still here with 18 engineers locally, 

and we’ve also added SI engineering 

groups in Taiwan, China, and Oregon. 

Could you tell us a little 

about the design support that 

Samtec offers? 

We try to differentiate ourselves 

from some of the larger connector 

companies with our level of support. 

When we started our group, most 

companies were providing good 

support to what we would call Tier 

1 companies, but they would pretty 

much ignore the smaller businesses. 

At Samtec, those smaller companies 

are a focus for us—we have around 

20,000 active customers today. Some 

of them don’t have engineers who 

are well versed in SI principles and 

problems. We’ve been willing to do a 

lot of work for them. One of our goals is 

to be “the easiest connector to design 

in.” Part of this requires very detailed 

characterization testing, and making 

this information easily available on the 

web. SI wise, connectors are poorly 

covered by industry standards, so test 

procedures are not well defined and 

data reporting is not standardized. 

We also do what we call “customer 

support R&D,” where we work to 

develop better test procedures. 

The end goal is to characterize our 

products fully so our customers can 

trust our data so they don’t have to do 

the characterization work themselves. 

We take this same approach to 

modeling, where we provide 

connector models in most popular 

formats. This has changed over 

the years; SPICE was king and we 

Samtec’s Avanced Design System (ADS) Interface 

provided as many as eight various 

flavors such as PSPICE and HSPICE. 

We did a lot of post-processing work 

to convert our files so they were pointand-click 

usable by our customers. 

As the industry has moved to more 

microwave-type simulators, we’ve 

changed our modeling processes so 

we can provide S-parameter models. 

We also work with simulation tool 

vendors directly—we buy some tools 

for the sole purpose of making sure 

our models work easily and correctly 

in each tool. 

What tools are the most 

popular? 

In the last four or five years, there’s 

been a trend toward more S-Parameter 

based simulators, where simulation 

times are faster than SPICE at 

higher frequencies. Agilent’s ADS is 

probably the most popular currently, 

but it’s a dynamic situation, with a lot 

of players trying to carve out a niche 

as the industry shifts. Back to our large 

customer base, we were fortunate 

because we could see the industry 

leaders in system design migrating 

towards ADS early on, as they’d ping 

us for certain types of models. That 

allows us to see over time where the 

industry is going as the newer tools 

progress and get cheaper, more user 

friendly ,and propagate through the 

industry. There are still many of our 

customers who use SPICE, so we 

can’t abandon SPICE models. We 

still provide backwards compatible 

and older format models for our less 

bleeding-edge customers. 

What is the process of 

designing your connectors? 

I’ve been designing connectors for 

more than 20 years, and in the past, 

connector design was primarily 

driven by mechanical issues. There 

was a lot of effort put into the physical 

interface design for robustness, 

reliability—those kinds of things. 

Of course, there have always been 



7


power and high current connectors, 

which have their own set of electrical 

issues. Even before SI issues were a 

factor, connectors were a challenging 

engineering problem. As signal 

speeds increased and form factors 

became smaller, the SI electrical side 

became much more important. Even 

as recently as two or three years ago, 

a lot of connectors were designed in 

an electrical vacuum, where there 

wasn’t much input provided by SI 

guys. Those days are ending. 

We SI guys still lose many engineering 

tradeoff battles. We do 3D electrical 

and mechanical simulations of 

every connector we design. The 

design process can be challenging, 

because many of the things we 

want to do from an EE perspective 

add cost and complexity, which 

makes the mechanical engineer’s 

job harder. Another challenge we 

face at Samtec is that, along with 

industry standard connectors, we 

offer many generic, non-standards 

based interfaces. Using PCI Express 

as an example, that interface is well 

defined, with things like signal and 

ground locations, shields, etc. The 

interface is defined, along with things 

like signal and ground locations, 

shields, etc. They also provide firm 

performance numbers that must 

be met. In a situation like that, we 

“A few years 

ago, Samtec 

acquired an 

optical engine 

design and 

fabrication 

company. We’ve 

been working 

on merging 

the two media 

and developing 

a system 

that allows 

customers to use 

fiber or copper, 

depending on 

their current 

and future 

performance 

requirements.“ 

could optimize things electrically to 

ensure we hit those specs. However, 

in generic connector applications, it’s 

more difficult because performance 

goals are often fuzzy. Some 

customers might use a connector in 

differential applications and some 

might use it single-ended. Many 

run differential and single-ended in 

the same connector. If we know it’s 

going to be purely differential, we can 

optimize it one direction, and vice 

versa if we know it’s single-ended 

only. But when we get into the mixed 

applications, it’s harder to optimize 

the electrical performance across all 

potential applications. Back to testing, 

this also requires us to characterize 

our connectors in many different 

configurations. 

What are some tips for finding 

the best connectors for a 

particular application? 

I’d say the biggest constraints are 

how much board space you have to 

work with, and how many signals you 

have to run. That drives everything. 

Once you have the general size 

nailed down and the configuration 

of the connector (whether it’s top 

entry, right angle, etc.), then you 

can start looking at which electrical 

parameter is most important in your 

particular application. In some 

cases, impedance performance 

might be important and in other 

cases, impedance might not matter 

much. The engineer needs to focus 

on which performance aspects are 

most critical in their application. Of 

course, if there is a spec in place, 

then it can be relatively easy to flip 

through a test report to see if the 

connector hits the specs. We also 

do quite a few system simulations 

on the front end, and publish those 

results in what we call an Application 

Note. For example, let’s take PCI 

express. A customer might have 

certain space requirement or a form 

factor in mind where a standard PCI 

express connector just won’t work, so 

they want to use one of our generic 

high speed connectors. What we do 

is take a system from the transceiver 

on one end to the transceiver on the 

other end, and then we add a certain 

amount of PCB trace in between. 

Then we add a connector pair in the 

middle and simulate that, and see if it 

meets the PCI spec requirements. We 

examine the eye patterns, and things 

like crosstalk and insertion loss. We 

might conclude something like, “With 

this pin out on this connector, you 

can operate PCI express at 4 Gb/sec 

with up to 12 inches of trace on each 

side”. We’ll typically publish multiple 

scenarios like this in an App Note, and 

many customers have come to rely on 

this type of information. If they have 

a situation that’s just a bit different 

than a case covered in an App Note, 

we’ll often perform a simulation 

for them based on their particular 

requirements. Probably 20% of 

our current SI engineering effort at 

Samtec is spent doing system-type 

simulations like this. 

What are some of Samtec’s 

new products? 

One of our newest products is 

a combination of fiber optic and 

copper cables, called “FireFly.” A 

few years ago, Samtec acquired 

an optical engine design and 

fabrication company. We’ve been 

working on merging the two media 

and developing a system that allows 

customers to use fiber or copper, 

depending on their current and future 

performance requirements. Typically 

this is inside the box, so it’s somewhat 

like a high speed back plane 

replacement. The module mounts 

on the motherboard and operates 

with a copper cable assembly for 

short distances and lower speeds. If 

the speed, distance, or possibly EMI 

requirements, go up in the future, the 

copper can be replaced with a plug-in 

fiber optic assembly. 

What other services does 

Samtec provide? 

We provide what we call a “Final Inch,” 

where we step outside the connector 

and look at the PCB area around the 

connector. We develop an optimized 

a PCB design for the breakout 

region in the area underneath the 

connector, including trace and via 

design and placement. We provide 

these designs in Gerber format along 

with SPICE models of the breakout 

region and traces. It makes sense 

for connector companies to do this 

because it’s basically the same for 

many applications. It doesn’t make 

sense to have to reinvent the wheel 

every time someone uses a connector. 

Similarly, we provide what we call 

intelligent PCB design libraries, 

which are libraries that a PCB 

designer can pull into his tool, which 

brings information on the footprint, 

pin numbering, schematic symbols, 

and sometimes information such as 

such as height and weight. 

We’re also seeing some system 

design tools evolving to where one bill 

of materials contains models that are 

used for several different design tools. 

The BOM is basically a collection 

or database of models. There will 

be footprint info and symbols for use 

in layout; height, width, and window 

information for thermal/airflow 

simulations; SPICE or s-parameter 

models for SI simulations; weight and 

height information for pick and place 

optimization, etc. So this mega model 

is a one stop shop that contains all 

the information about the connector 

that’s needed from start to finish in the 

system design process. We work to 

stay abreast of such developments, 

and we often participate in industry 

efforts to develop standards for things 

like this. It’s all part of our goal of 

making our customer’s job easier. ■ 



9

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11

EEWeb PULSE TECH ARTICLE 

Facing the 

Counterfeit 

Alan Lowne 

CEO, Saelig Co. 

IC 

THE PROBLEM 

Issue 

Alan Lowne 

CEO, Saelig Co. 

ICs are not like hard-to-copy banknotes, and making fake “lookalike” 

parts which resemble real ones takes very little skill. Counterfeiting 

simply requires finding cheap parts in the same package and painting 

new marks on them. The problem of counterfeiting has arisen due to the 

high value of electronics parts, and the whole manufacturing chain, from 

assembly house to end-user, is vulnerable. The number of companies 

that have been duped by batches of fake devices is incalculable. 

Counterfeiting semiconductors has been rapidly increasing, impacting 

a wide variety of electronics systems used by a wide gamut of involved 

parties – consumers, businesses, and military customers. The detection 

of counterfeit components has become an increasingly important priority, 

especially for electronics manufacturers and component suppliers 

worldwide. 



13


Reports 

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Counterfeiting accounts for more than 

8% of global merchandise trade, trade which and is 

equivalent is equivalent to to lost lost sales of of as up much to as 

$600B and will grow to to $1.2T by by 2009 

US Dept Dept. of Commerce 

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WHAT ARE COUNTERFEIT COMPONENTS? 

The most prevalent counterfeiting technique is a rebadged 

product. It is a simple matter to remove the 

existing mark from a chip package and put on a new 

logo and part number, a different brand, or a different 

speed, and sell the semiconductor to an unsuspecting 

buyer who has no way of making sure that the product is 

“real”. Sometimes the purchased chip is only an empty 

package with no die inside. It is true that the finished 

system would fail before it left the factory – but this failure 

still requires expensive investigation and rework. With 

no part available to replace the bad one, such a failure 

can cause the dreaded exclamation “Line Down!” Worse, 

sometimes the failure of borderline ICs may not occur 

until the system is in the field, and field repairs can cost 

ten times as much to fix as those caught before they 

leave the factory. 

Counterfeiting can also be from chips which are gleaned 

from discarded scrap boards. After being remarked with 

a different manufacturer’s logo, they are inserted into the 

supply chain and sold to innocent buyers – who naturally 

who assume that the products are genuine. 

Usually, it is impossible to identify counterfeit components 

until they are fitted on a PCB and the first tests are made 

on the final product. Failure requires the costly identification 

of the components at fault and which then must be 

lifted from all boards in the production line. Complete 

Year 

batches of finished products may need to be recalled to 

the factory – directly hurting a company’s bottom line. 

There have been several technical measures to solve 

this problem in the past, including visual inspection of 

devices for marking errors – which needs a trained eye 

for all possible variations in marking. Electronically testing 

or x-raying every incoming batch is another technique. 

One more method, which is rather destructive, is to use 

a complex decapsulation system in order to visually 

inspect IC die sample. This method causes an immediate 

loss of revenue due to the component’s destruction. 

Not only is this method expensive and time consuming, 

it requires complex training, skilled operators, and expensive 

equipment. 

SCREENING 

Some distributors have advertised their screening services 

for verifying components, with a turnaround time 

of “as little as two days,” which is still unacceptable in 

many cases. These companies offer techniques such as: 

x-ray, x-ray fluorescence analysis (XRF), decapsulation, 

heated solvent testing, visual inspection, and solderability 

testing. These tests result in detailed reports when all 

that was really required was the simple question, “is it 

a good part?” In reality, this approach is only viable for 

military or large volume production runs. 

What the electronics manufacturing industry really needs 

Figure 2: Chip package markings can be made to look almost identical 

to the uncritical observer. 



Can you 

tell which is 

the genuine 

IC? 

The outside package marking in this case 

does not match the die inside when the top 

cover is destructively removed. 

15


is a tool that can verify the identity of received ICs quickly 

and economically, using a statistically significant procedure. 

This tool would have to be suitable for all devices 

and packages, simple to use by any operator, and would 

need to give fast “good/suspect/fail” results. 

In fact, there is such a commercially-available device 

– the ABI SENTRY Counterfeit IC Detector. SENTRY is 

a PC-driven product that 

uses a complex PinPrint 

Test Algorithm to check 

the validity of parts in seconds. 

The product is very 

simple to use and enables 

any receiving department 

to operate the equipment 

with minimal training. The 

analysis takes place in the 

background and the operator 

only sees a simple 

“Good Device”, “Blank 

Device” or “Fail Device” 

message, with the option to 

produce a detailed report 

to send to the supplier. 

SENTRY contains a set 

of ZIF sockets accepting 

adapters for DIP, SOIC, 

BGA, SSOP, as well as discrete components. The system 

uses a comparative technique to rapidly analyze and 

learn new components, and then test the unknown parts. 

A known good component is locked into the ZIF socket 

while a test pattern is applied across all its pins. The 

component’s response to this test pattern, or PinPrint, 

SENTRY is a 

practical and 

affordable solution 

for solving the 

counterfeit IC 

issue, using its 

rapidly-built 

dedicated library 

of component data 

to cross-check 

each part tested. 

is automatically measured and stored as a benchmark. 

SENTRY uses a combination of electronic parameter 

settings (voltage, frequency, source resistance, and waveform) 

to generate the “signature” for each pin of the IC 

being checked. It then compares the unique electrical 

characteristics of known components and with suspect 

components. Testing between every possible pin combination 

is included, maximizing the chances of capturing 

internal fault conditions. 

SENTRY can quickly detect 

missing or incorrect dies, 

lack of bond wires, inaccurate 

pin outs, and pin 

impedance variations. 

Simple pass or fail results 

are returned after testing, 

offering a high level of confidence 

in the authenticity of 

components. 

As parts become increasingly 

complex, 100% testing 

becomes burdensome, but 

testing one or two pieces 

for, say, 200 pieces is manageable. 

Experience has 

shown that variations arising 

from a suspect shipment 

will reveal themselves 

well before such a test is complete. Nevertheless, if 100% 

non-destructive testing is required, using a SENTRY 

Counterfeit IC Detector is the ideal solution! 

SENTRY is a unique solution for the quick and easy 

detection of counterfeit ICs and components. It is able 

to identify parts that have a different internal structure, 

or no structure at all, and even components originating 

from a different manufacturer. SENTRY is an easy to use 

instrument, capable of checking all types of components, 

ranging from simple two pin devices to more complex 

packages such as QFP and BGA. 

Controlled via USB using the provided PC software, SEN- 

TRY’s device library can be built up by adding specific 

known good devices. Each device can have documents 

associated with it, such as photos of device markings, 

data sheets, and other documents, to further help in confirming 

the integrity of a device. SENTRY contains all the 

hardware required to analyze the electrical characteristics 

of ICs with up to 256 pins. 256 pins+ devices can also be 

tested by rotating the device (BGA, QFP) to allow all pins 

Figure 3: SENTRY software screenshots. 

to be learned and compared. SENTRY is supplied with 

four 48 pin dual in line (DIL) zero insertion force (ZIF) 

sockets; these sockets can be used directly for older DIP 

components but can also be used to accommodate a 

variety of additional socket adapters available for different 

package types. The socket adapter can contain multiple 

IC sockets if required, to allow testing several ICs at the 

same time, or allow one IC to be compared to another. 

An expansion connector allows custom socket adapters 

with up to 256 pins to be attached. 

Designed in Europe by ABI Electronics Ltd., a leading 

manufacturer of PCB testing equipment, SENTRY 

has been conceived with component distributors and 

manufacturer Receiving Departments in mind for sample 

testing. Other application areas include electronics components 

suppliers using SENTRY to improve their quality 

assurance programs. Detailed reports can be saved 

to provide quality control traceability. SENTRY guards 

production facilities from the infiltration of counterfeit 

devices, identifying bad parts before they are mounted 

on PCBs; this protection saves time, money and frustration, 

and SENTRY does not require any knowledge of 

electronics to use efficiently. After testing, the operator 

can just be presented with a simple “Good Device”, 

“Blank Device” or “Fail Device” message, but for in-depth 

analysis, PinPrints can be reviewed and full reports can 

be generated. In order to ensure consistency throughout 

the whole supply chain, SENTRY is designed to support 

data sharing – the PinPrints of a given component can 

be shared between users, from the OEM through to the 

distributor and end user. 

ABI Sentry is housed in a sturdy metal box (10.6” x 10” 

x 3.6”) and weighs 8lbs, and can receive separate interchangeable 

adapters for accepting various IC packages 

under test. With its large range of optional adapters, 

SENTRY can accommodate most types of IC packages, 

including DIP, SOIC, PLCC, QFP and even BGA. For 

simplicity of operation, SENTRY has no display or keypad, 

but is entirely controlled by a PC via USB using ABI’s 

custom designed free software. 

SENTRY is a practical and affordable solution for solving 

the counterfeit IC issue, using its rapidly-built dedicated 

library of component data to cross-check each part tested. 

With lead-time issues making ICs harder to acquire to 

meet aggressive manufacturing schedules, identifying any 

parts that are not “real” before they enter production can 

potentially save every manufacturer a great deal of time 

and money – as well as that intangible but irretrievable 

quality – brand reputation. 

For more information, visit: 

www.saelig.com 



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Picking 

Components 

Tamara Schmitz 

Intersil Applications 

Manager for Optical Sensors 

With 

Confidence 

So So you you have a a circuit schematic you you want to to build. That 

seems simple enough. If If you you have a a well-equipped lab lab at at 

your disposal (possibly with a a lab lab manager to to guide you), 

then this this article is is not not for for you. However, if if you you will will need to to 

order electronic components for for your project, this this will will offer 

some insight and and advice. 



21


The two most popular places to order a wide range of 

electronic components are mouser.com and digikey.com. 

I’m going to reference Digikey since I’ve been to their 

headquarters in Thief River Falls, Minnesota and can 

vouch for the extent of their inventory and the efficiency 

of their factory. 

To simplify our discussion, let’s choose one component 

to discuss: a resistor. If I ask Digikey’s search engine for 

a resistor, it returns a list with seven subheadings under 

“Resistor.” None of them are an obvious choice, such as 

“general purpose resistor.” Instead, they are categorized 

by the way they are mounted: surface mount, through 

hole, chassis mount, array, precision or accessories. 

Brute force dictates that you just start clicking and hope 

for pictures that can be deciphered. (Mouser categorizes 

the resistors by their composition material, by the way.) 

Before choosing any component, you need to know 

about its function in the circuit. How much current travels 

through it? Is it in the power path? Is it in the signal path? 

How fast are the frequencies that must travel through it? 

If a component is in the power path, you might want to 

optimize its current carrying capability, heat dissipation, 

and charge storage (for capacitors). If a component is in 

the signal path, you have to consider the frequencies of 

the signals in the system. If it is a low frequency system, 

then there really aren’t any special requirements. Any 

component will work. If it is a high frequency system 

(hundreds of megahertz or higher), then you have to 

be more careful with your selection. The parasitics of a 

component can cause unwanted disturbances in your 

circuit. To first order, the smallest components are used 

in high frequency paths (like sports cars) and the largest 

components are needed in power systems (like tractor 

trailers or dump trucks). 

Back to that list of choices under “Resistor.” “Through 

Hole” is the type of resistor that has been around for years, 

as shown in the figure to the right. This resistor is called 

“through hole” because the wires attached to each end 

go through plated holes in a printed circuit board (PCB). 

The value of the resistor is given in a color code of the first 

three bands. The fourth band designates the tolerance. 

The second most typical choice is “Surface Mount.” 

Like the name suggests, these resistors do not penetrate 

through a PCB, they are soldered to pads on either side 

of it. Given the compact structure, this type of device is 

perfect for high frequency circuits. (They are also perfect 

for portable equipment.) Surface Mount Devices (SMDs) 

come in a variety of sizes. The largest size I’ve used is 

1206 (about 0.12” x 0.06”). The next size to come along 

was 0805 (about 0.08” x 0.05”). There is also 0603, 0402, 

0201, and 01005. If you are going to solder these by hand, 

then I suggest sticking to the two largest values. When I 

was in graduate school and at the peak of my soldering 

skills, I could solder a 0402 component reliably and an 

0201 component with about a 65% success rate. Fifteen 

years later, my clumsier fingers are much more comfortable 

with 0805 and I groan when forced to deal with 0603. 

The choices for resistors are less common. “Chassis 

mount” commonly refers to a type of resistor with a tab 

that allows you to mount it with a screw or bolt to a case. 

“Array” refers to a set of resistors in a chain like steps in a 

ladder. These are commonly used in simple conversion 

circuits. “Precision” refers to specially-trimmed components 

with values more exact than typical component 

values. (This type of precision costs, of course.) 

Let’s assume you will choose a surface mount resistor 

and proceed to the selection page. Since there are more 

than 276,000 available, let’s narrow it down with the filters. 

I don’t usually limit myself to a particular manufacturer 

or series, since the component characteristics are far 

more important to me. Instead, let’s look at temperature 

coefficient. Temperature coefficient is the amount a component’s 

value will change as temperature changes. A 

smaller number is better. Next is tolerance. Tolerance is 

the allowed deviation from the predicted value. Tolerance 

is always plus or minus, so it is also the variability of the 

component. Again, a smaller number is better and will 

be more expensive. 

For package and size, refer to the earlier discussion on 

attempting to solder different sizes of components. You 

can also specify a certain height for a package. (I assume 

there might be reasons why you would need to ensure the 

height does not exceed a certain value.) The packaging 

category refers to bulk orders and what type of automated 

machinery is being used to assemble electronic circuitry. 

The filters I have skipped are the most important ones. 

Resistance value must guide your selection. Also, please 

pay attention to power dissipation. Once 

you know the DC and AC current through 

your component, you can calculate the 

power dissipation. For safety, order a component 

with more power capacity than is 

needed. (There could be shorts or surges 

and you don’t want the component to be 

destroyed.) 



P = I 2 R. 

A detailed discussion of resistor composition 

is beyond the scope of this discussion. 

I don’t tend to limit this field when searching 

for a resistor, but I still like to have an 

idea of the options. Carbon resistors tend 

to be low wattage. Wire wound resistors, 

on the other hand, tend to have high wattage 

capability. 

The features add yet another flavor to this 

discussion. Military (and Automotive) qualified components 

have a wider temperature range and tougher 

qualifications. (Only pay for this if you need it.) Current 

sense resistors typically are small value resistors placed 

in series with the power supply to monitor it. Most of the 

other options are self-explanatory. 

Most of the circuits I see on a daily basis are composed of 

surface mount components. For sensors, surface mount 

components are used exclusively. For an example, with 

a resistor, take a look at the ambient light and proximity 

sensor, the ISL29038, in the figure above. It is used in 

handheld devices, like smartphones. The ambient light 

sensor monitors the surrounding brightness to allow the 

backlight of the screen to dim and save power when 

appropriate. The proximity sensor senses when you are 

bringing the phone to your ear to talk on the phone and 

disables the screen. 

In this case, surface mount components make sense 

because of their small size. (Smart phone makers, in fact, 

do prefer to use 0201 components around this part when 

possible.) For the eval board, which is hand assembled 

and most likely hand tested by the customer, 0805 components 

are friendlier. Compare the size of the R_EXT 

resistor to the standard paperclip in the figure. R_EXT 

sets the bias current for the device. It is not in a signal 

path. It has no high frequency signals through it. Still, 

it is good practice to keep it close to the sensor. Surface 

mount devices can be packed closely together. 

As a matter of fact, in most situations, surface mount 

An example circuit with surface mount components. R_EXT 

is an 0805 surface mount resistor with a value of 499k ohms. 

The standard paperclip is for size reference. 

components are my go-to package of choice. I would 

only choose through hole components if there was a high 

current supply, like 10 amps or more. This could still be 

handled with surface mount components, but would need 

good board layout with proper layers. 

If you happen to be working on a board where you push 

connections together (no solder), then you’ll be happy to 

know that there are conversion boards available so that 

you can still prototype with surface mount components. 

However, the conversion board will add parasitics that 

may affect the performance of your prototype. 

All in all, prototyping is a lot of fun. Don’t let the daunting 

task of ordering a component stop you from building that 

new idea or fun circuit you’ve wanted to try! 

About the Author 

Tamara Schmitz is a Senior Principal Applications Engineer 

and Global Technical Training Coordinator at 

Intersil Corporation, where she has been employed since 

mid 2007. Tamara holds a BSEE and MSEE in electrical 

engineering and Ph.D. in RF CMOS Circuit Design from 

Stanford University. From August 1997 until August 2002 

she was a lecturer in electrical engineering at Stanford; 

from August 2002 until August 2007, she served as assistant 

professor of electrical engineering at San Jose State 

University. Her interests include traveling, woodworking, 

dog training, playing guitar and accordion, and following 

major league baseball/college football. 

To read more from this author, visit her EEWeb profile. 

23

EEWeb PULSE PROJECT 

The 

Raspberry 

Pi PART 2: 

Kyle Olive 

Computer Engineering Student & 

IEEE Student Branch Chair 

Raspberry Pi is a trademark of the Raspberry Pi Foundation 

Raspbian Wheezy 

(with Setup Guide), 

Arch Linux ARM 

This is the second installment 

in my series on Raspberry 

Pi. If you haven’t worked with 

Raspberry Pi before, please read 

my article “The Raspberry Pi: Introduction 

and Required Hardware“ to 

begin the series. 

If you’re reading this article you’ve 

got your hands on a Raspberry Pi, 

and you’ve got all the hardware you’ll 

need to get yourself up and running. 

Unfortunately, until you’ve set up an 

operating system, you’re not going 

to get a whole lot of use out of it! 

This article will outline two different 

popular operating systems for the 

Raspberry Pi, Arch Linux ARM and 

Raspbian “Wheezy,” as well as go 

through a set-up guide for Raspbian. 



25


Operating System Comparison: Arch Linux ARM 

and Raspbian “Wheezy” 

So, does it even make a difference as to which operating 

system you choose? In short, it depends. Depending on 

your skills and on your knowledge of Linux operating 

systems, the choice of operating system may not be an 

important one, but if you’re 

new to this realm of development, 

then there are some 

things to consider. 

If you are new to Raspberry 

Pi, you might want to choose 

the recommended Raspbian 

“Wheezy” (http://www.raspbian.org/) 

operating system, 

which is based off of the 

popular Debian linux distribution, 

and is much friendlier 

to users who may not be too 

experienced with using Linux. 

Wheezy comes pre-packed 

with the LXDE (http://lxde. 

org/) desktop environment, a 

bunch of sample applications 

developed for the Raspberry 

Pi, and applications like Midori (a web browser) and 

Scratch (a graphical educational programming language). 

On top of that, it also has many of the standard requirements 

for development (gcc, python, and more) prepackaged 

and ready to go. If you want to be able to get 

started using your Raspberry Pi as quickly as possible 

and with minimal hassle, or if you wanted to be able to 

start using your Pi in an educational setting, your best 

bet is to go with this distribution. 

On the other hand, you 

might want to choose Arch 

Linux ARM if you are a bit 

more experienced. Those 

familiar with the desktopbased 

Arch Linux will know 

that setting it up is a more 

involved process than other 

distributions, and Arch 

Linux ARM is no different. 

The base image for Arch 

Linux ARM is very lightweight, 

containing only the 

necessary software packages 

to get your Pi running. 

Raspbian 

“Wheezy” is 

easier to set up, 

has a higher 

number of available 

software 

packages, and has 

a higher number 

of active users. 

While this means a much longer, more involved setup 

process however, it also means that developers will be 

able to cut out a good portion of the software that they 

don’t need, resulting in a faster, more lightweight, operating 

system. 

Though there are more differences between the distributions 

than discussed above, 

most users will probably want 

to use Raspbian “Wheezy”. It’s 

easier to set up, has a higher 

number of available software 

packages, and has a higher 

number of active users (in 

other words, you will have 

more people to ask for help 

from when something goes 

wrong). Raspbian “Wheezy” 

will generally be a better 

choice for random tinkering, 

while Arch Linux may be a 

better choice for an experienced 

developer with a well 

defined project. 

This article will explain setting 

up Raspbian “Wheezy,” but 

keep an eye out on EEWeb.com for a more in-depth 

discussion of Arch Linux ARM and a guide for how to 

set it up on a Raspberry Pi. 

Setting up Raspbian “Wheezy” 

To install Raspbian “Wheezy” on your Raspberry Pi, you’ll 

need the Rhaspbian image (available here) and an SD 

Card with at least 2GB of memory. If you plan on doing 

Figure 1: Win32 Disk Imager Tool being used to write the Rhaspbian image to SD Card 

Figure 2: Use “df” to get the correct drive path. 

something with your Pi that involves multimedia (videos, 

music, games, etc.) then you probably want to have a 

bigger SD Card (I’m currently running with an 8GB). 

First we’ll have to transfer the image to the SD Card. 

Mount your SD card on your computer, and extract the 

.img file from the archive you downloaded into a folder 

on your computer. It’s important that you don’t just copy 

the image you downloaded to the SD Card, as that won’t 

actually format it in a way the Pi can read. The following 

steps will delete all data on the SD Card, so if you already 

have stuff on there you will want to back it up. 

In Windows you’ll want to use a tool like Win32-Image- 

Writer. Extract the binary archive to a folder on your 

computer, and run Win32DiskImager.exe. Select the 

wheezy image you extracted as the image file, and the 

drive letter for your mounted SD card. Then press “write” 

and let the program do its thing. In a few minutes you 

should get a notice that the write was successful. 

In Linux you’ll want to use the “dd” command. You first 

need to mount your sd card and then find its device name 

by running the “df -h” command. The device name will 

be something like /dev/sdb/ (note: if your SD card has 

multiple partitions (sdb1, sdb2, etc) you want to use all 

the partitions (sdb)). You then have to unmount the card 

in order to format it. You can do so using a graphical 

context menu in the file explorer of most Linux distros, 

or use the “umount” command. 

Run df-h once before inserting your SD Card to see the current drives 

Run df-h again after inserting your SD 

Card to see its filesystem path and mount 

location. 

The SD Card will be the new addition. In 

this case, we will want to write our image 

to /dev/sdb. 

Run df-h once before inserting your SD Card 

to see the current drives 

Figure 3: The dd command output. It can take a few minutes for the image to be written to the SD Card. 

Once you’ve gotten the device name of your SD card 

and you’re ready to setup the SD card use the command: 

sudo dd bs=1M if=[WHEEZY IMG DIRECTORY] 

of=[SDCARD DEVICE PATH] 

IMPORTANT: 

Ensure your SD Card 

is correctly pointing 

to your SD Card, otherwise 

you can wipe 

your drive of all data. 

This will format your SD card (output file) with your 

Wheezy image (input file) using 1MB blocks. 

The command will take a few minutes to run, when it’s 

finished you can eject your newly imaged SD card and 

put it into your Raspberry Pi. 

Start up your Raspberry Pi and in a minute or so you’ll 

be greeted with a blue screen and the Raspbi-config 

menu. This menu will help you go through the process 

of setting up your operating system. We’ll walk through 

the settings here in this article. Accepting the defaults 

will usually work fine, though you may want to fine tune 

some of the following settings. 



27


Making Wireless 

Truly Wireless: 

Need For Universal 

Wireless Power 

Solution 

Dave Baarman 

Director Of 

Advanced Technologies 

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minima veniam, quis nostrum exercitationem ullam corporis suscipit 

laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem 

vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil 

ARTICLES 

JOBS 

COMMUNITY 

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TODAY 

expand_rootfs – This setting will let you expand the root 

partition of Raspian Wheezy to fill the entire SD card. If 

you’re planning on using your SD card to store other data 

or want to manage partitions yourself, then don’t use this 

option. Otherwise, select it and it it expand the filesystem 

to use the entire SD card. After selecting it, you should 

be greeted with a message stating that the filesystem will 

expand on reboot. 

overscan – This lets you enable or disable overscan. If 

you notice that your display isn’t filling your entire monitor, 

disabling overscan will usually fix that issue. 

configure_keyboard – If you’re using an international 

keyboard, you can use this option to change keyboard 

settings. 

change_pass – The default login and password for Raspbian 

Wheezy is pi : raspberry. If you would like to change 

this, you can do it here. 

change_locale – This lets you change your locale, and 

sets languages and character sets appropriately. This 

defaults to British English. 

change_timezone – Lets you set your timezone. 

memory_split – This lets you set how much of the memory 

is dedicated to the graphics processing unit of your 

Raspberry Pi. The more graphically intensive applications 

you’ll be working with, the higher this value should be. 

The default of 64 should be fine for most applications. 

overclock – This lets you change the clock rate and 

voltage levels of your Raspberry Pi to some pre-set defaults. 

Note that overclocking can potentially lower the 

lifespan of your Pi and may lead to other issues. Only 

play with clock speeds if you know what you’re doing. 

ssh – If you want to be able to ssh into your Raspberry Pi 

and use it remotely, enable this setting. 

boot_behaviour – Lets you set up the Pi so the desktop 

environment starts automatically (otherwise you’ll have 

to use the command startx to start it) 

update – Finally, update will check for updates to the 

config tool. 

Once you’ve selected the settings you want, select “finish” 

and restart your Raspberry Pi (when prompted to login 

the default username is “pi” and the default password 

is “raspberry”). If everything went smoothly you should 

now be greeted by the desktop (if you have enabled it 

to start by default – you can run startx to have it launch 

otherwise). Hopefully you didn’t run into any issues. If 

you did, you can always try again by re-formatting the 

SD card with the original Wheezy image, or head over 

to the Raspberry Pi forums and FAQs to look for more 

pointers and tips. 

Once you’ve got your Raspberry Pi set up with Rhaspbian, 

you’re ready to start developing. 

To read Part 1 of this series, click the image below: 

To find out more information about Raspberry Pi or to purchase 

Raspberry Pi products, visit their website at: 

www.raspberrypi.org 



29

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