About Circuit Cellar Staff

Circuit Cellar's editorial team comprises professional engineers, technical editors, and digital media specialists. You can reach the Editorial Department at editorial@circuitcellar.com, @circuitcellar, and facebook.com/circuitcellar

Wireless Product Regulations (EE Tip #123)

Are you working on a wireless design that you’d like to bring to market? If so, be sure to anticipate regulatory constraints right from the start. Planning upfront will save you a lot of time, money, and hassle.

Electrical engineer Robert Lacoste notes:

Unless you’re working on a prototype that won’t ever leave your lab, there is a high probability that you will need to comply with some regulations. FCC and CE are the most common, but you’ll also find local regulations as well as product-class requirements for a broad range of products, from toys to safety devices to motor-based machines. (Refer to my article “CE Marking in a Nutshell,” Circuit Cellar 257, for more information.CE Mark

Let’s say you design a wireless gizmo for the U.S. market and later find that your customers want to use it in Europe. This means you lose years of work, as well as profits, because you overlooked your customers’ needs and the regulations in place in different locales.

When designing a wireless gizmo that will be used outside the U.S., having adequate information from the start will help you make good decisions. An example would be selecting a worldwide-enabled band like the ubiquitous 2.4 GHz. Similarly, don’t forget that EMC/ESD regulations require that nearly all inputs and outputs should be protected against surge transients. If you forget this, your beautiful, expensive prototype may not survive its first day at the test lab.

Lacoste’s full article appeared in Circuit Cellar’s anniversary issue, CC25.

Internet of Things Challenge: WIZnet Connect the Magic 2014 Launches

Elektor International Media (EIM) and WIZnet Co, Ltd today officially launched the WIZnet Connect the Magic 2014 Design Challenge, which is a five-month-long contest for electrical engineers, students, and DIYers to develop innovative, ’Net-connected electronic systems around a WIZNet WIZ550io Ethernet controller module or W5500 chip.

According to the Challenge’s rules, entrants must use at least one WIZnet WIZ550io or W5500 chip in a project. Entries will be judged on their technical merit, originality, usefulness, cost-effectiveness, and design optimization. Winners will receive a share of $15,000 in prizes and recognition in Elektor and Circuit Cellar magazines. The entry submission deadline is August 3, 2014.

WIZnet's WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

WIZnet’s WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

The WIZ550io is an auto-configurable Ethernet controller module that includes the W5500 (TCP/IP-hard-wired chip and PHY embedded), transformer, and an RJ-45 connector. The module has a unique, embedded real MAC address and auto network configuration capability. The W5500 chip is a Hardwired TCP/IP embedded Ethernet controller that enables Internet connection for embedded systems using Serial Peripheral Interface (SPI).

“The WIZnet Connect the Magic 2014 Design Challenge is an excellent opportunity for engineers, designers, and students to build ’Net-connected systems with WIZnet’s WIZ550io auto-configurable Ethernet controller module and W5500 chip,” said C. J. Abate, Editor in Chief for EIM’s Circuit Cellar magazine.

The challenge is intended to engage more engineers and innovators in the Internet of Things revolution, which has become a major focus for electronics developers worldwide during the past several months.

W5500

WIZnet W5500 chip

“The engineers, students, and academics that read our publications and comprise our community see the Internet of Things as more than a convenience. They see it as an opportunity—that is, an opportunity to create cutting-edged connected devices and bring them to market,” Abate said. “Thus, it’s our job to introduce our community members to the best components and tools to achieve their IoT-related design goals. We’re doing that by managing this challenge for our partner, WIZnet, whose W5500 chip and WIZ550io Ethernet module enable designers to quickly develop ’Net-connected systems.”

WIZnet has made available a limited number of free WIZ550io Ethernet controller modules for use in the WIZnet 2014 Connect the Magic Design Challenge. To submit a request for a free WIZ550io module, eligible participants can fill out an online sample request form at http://circuitcellar.com/wiznet2014/samplerequest/.

WIZnet is a private fabless semiconductor company founded in 1998 in Korea. WIZnet provides IOcP (Internet Offload co-Processors) and HW TCP/IP chips, best fitted for low-end Non-OS devices connecting to the Ethernet for the internet of things. Visit www.wiznet.co.kr/ for more information.

Elektor International Media (EIM) is the world’s leading source of essential technical information and electronics products for pro engineers, electronics designers, and the companies seeking to engage them. Each day, its international team develops and delivers high-quality content—via a variety of media channels (e.g., magazines, video, digital media, and social media) in several languages—relating to embedded systems, electronics design, DIY electronics, and hi-fi audio. EIM’s brands include Elektor, Circuit Cellar, audioXpress, and Voice Coil. Visit www.elektor.com for more information.

Design Challenge Contact
Challenge Administration
EIM/Circuit Cellar
contest@circuitcellar.com
860-289-0800

WIZnet Support
Americas: support_team@wiznettechnology.com
Asia: support@wiznet.hk
China: support-bj@wiznet.hk
EU: support@wiznet.eu
Korea: support@wiznet.co.kr

Circuit Cellar Editorial
Mary Wilson
Managing Editor
mary@circuitcellar.com
860-289-0800

Electrical Engineering Crossword (Issue 284)

The answers to Circuit Cellar’s March electronics engineering crossword puzzle are now available.

284-crossword-key

Across

1.    CROSSEDFIELDAMPLIFIER—This vacuum tube is capable of high output power [three words]
3.    HYPERVISOR—Produces and runs virtual machines
5.    DYNATRON—Uses negative resistance to keep a tuned circuit oscillating
8.    ULTRAVIOLETLIGHT—Gives some substances “a healthy glow” [two words]
13.    ZEROMOMENTPOINT—A moment of respite for robots [three words]
14.    THERMOSONIC—Connects to silicon ICs
17.    CATSWHISKER—An outdated electronic component mainly used in antique radios [two words]
18.    FLEMINGVALVE—Invented in the early 1900s, this was known as the first vacuum tube [two words]
19.    BACKBONE—Makes LANs connect

Down

2.    DEMODULATOR—Recovers information from a regulated waveform
4.    SQUEGGING—This type of circuit oscillates erratically
5.    DOWNMIXING—Audio manipulation process
6.    REYNOLDSNUMBER—Used for flow pattern predictions [two words]
7.    LATENCY—Used with bandwidth to ascertain network connection speed
9.    THICKFILM—This type of chip resistor is commonly used in electronic and electrical devices [two words]
10.    DYNAMIC—Its memory is volatile
11.    CRYOTRON—Operates via superconductivity
12.    NETMASK—Creates neighborhoods of IP addresses
15.    HOROLOGY—E.g., clepsydras, chronometers, and sundials
16.    SEEBECK—An effect that creates electricity

 

 

Client Profile: ImageCraft Creations, Inc.

CorStarter prototyping board

CorStarter prototyping board

2625 Middlefield Road, #685,
Palo Alto, CA 94306

CONTACT: Richard Man,
richard@imagecraft.com
imagecraft.com

EMBEDDED PRODUCTS:ImageCraft Version 8 C compilers with an IDE for Atmel AVR and Cortex M devices are full-featured toolsets backed by strong support.

CorStarter-STM32 is a complete C hardware and software kit for STM32 Cortex-M3 devices. The $99 kit includes a JTAG pod for programming and debugging.

ImageCraft products offer excellent features and support within budget requisitions. ImageCraft compiler toolsets are used by professionals who demand excellent code quality, full features, and diligent support in a timely manner.

The small, fast compilers provide helpful informational messages and include an IDE with an application builder (Atmel AVR) and debugger (Cortex-M), whole-program code compression technology, and MISRA safety checks. ImageCraft offers two editions that cost $249 and $499.

The demo is fully functional for 45 days, so it is easy to test it yourself.

EXCLUSIVE OFFER: For a limited time, ImageCraft is offering Circuit Cellar readers $40 off the Standard and PRO versions of its Atmel AVR and Cortex-M compiler toolsets. To take advantage of this offer, please visit http://imagecraft.com/xyzzy.html.


 

Circuit Cellar prides itself on presenting readers with information about innovative companies, organizations, products, and services relating to embedded technologies. This space is where Circuit Cellar enables clients to present readers useful information, special deals, and more.

DDS Basics (EE Tip #122)

The simplest form of a digital waveform synthesizer is a table look-up generator (see Figure 1). Just program a period of the desired waveform in a digital memory (Why not an EPROM for old timers?), connect a binary counter to the address lines of the memory, connect a DAC to the memory data lines, keep the memory in Read mode, clock the counter with a fixed-frequency oscillator FCLOCK, and voilà, you’ve got a waveform on the DAC output. Don’t forget to add a low-pass filter to clean the output signal, with, as you know, a cut-off frequency a little less than FCLOCK/2 to please Mr. Nyquist.

Figure 1: The most basic digital signal generator is built with a simple binary counter. Its output sequentially addresses the rows of a memory, which holds the successive points of the output signal. It is then converted to an analog signal and filtered.

Figure 1: The most basic digital signal generator is built with a simple binary counter. Its output sequentially addresses the rows of a memory, which holds the successive points of the output signal. It is then converted to an analog signal and filtered.

This design works, but it is not too flexible. If you want to change the output frequency, you need to change the clock frequency, which is not easy to do, especially if you need a fine resolution.

The direct digital synthesizer (DDS) architecture is an improvement on this original design (see Figure 2). Rather than add one to the table look-up address counter at each clock pulse like the counter did in the previous example, a DDS uses an N-bit long-phase register and adds a fixed-phase increment (W) at each clock pulse to this register.

Figure 2: The basic architecture of a DDS is a variant of the counter-based digital generator, but it allows a fine frequency resolution thanks to a phase register and a binary adder. The key point is that the increment is not necessarily a divider of the phase register maximum value.

Figure 2: The basic architecture of a DDS is a variant of the counter-based digital generator, but it allows a fine frequency resolution thanks to a phase register and a binary adder. The key point is that the increment is not necessarily a divider of the phase register maximum value.

N can be quite high (e.g., 32 or 48 bits), so only the most significant bits of the phase register are used to select a value from the phase-to-amplitude look-up table, which is usually nothing more than a ROM preprogrammed with a sine waveform. Assume that you are using the P most significant bits as an address. Then the output of the lookup table is routed to a DAC. And, of course, the analog signal finally goes through a low-pass filter, which is called a “reconstruction filter.” You will understand why in a minute.

How does it work? If the phase increment W is set to one, you will need 2N clock pulses to go through all of the values of the look-up table. One sine period will be generated on the FOUT output each 2N clock pulses, exactly like the aforementioned counter-based architecture. If W is 2, it will be twice as fast and the output frequency will be doubled. As you know, you need a little more than two samples per period to be able to reconstruct a sine signal, so the maximum value of W is 2N–1 – 1. The formula giving the output frequency based on the phase increment is then:DDS-EEtip-122-eq1

Don’t be confused. It is not a simple programmable divider because the phase register doesn’t loop back to the same value after each generated period. The table in Figure 3 may help you understand it.

Figure 3: his spreadsheet simulation shows the “phase wheel” concept. A fixed angle is added to the phase register at each clock pulse. Note that each period of the output signal is not identical to the previous ones because the phase doesn’t go back to the same value after a full turn.

Figure 3: This spreadsheet simulation shows the “phase wheel” concept. A fixed angle is added to the phase register at each clock pulse. Note that each period of the output signal is not identical to the previous ones because the phase doesn’t go back to the same value after a full turn.

What make a DDS a fantastic building block are the numeric examples. Just take a standard, low-performance DDS with a phase register of N = 32 bits and a reference clock FCLOCK = 20 MHz. Your DDS can then generate any frequency from DC to nearly 10 MHz with a resolution of the following:DDS-EEtip-122-eq2

Not bad. In fact, the maximum frequency will be a little lower due to constraints on the low-pass filter.—Robert Lacoste, “Direct Digital Synthesis 101,” Circuit Cellar 217, 2008. The issue is available in the CC Webshop.