The October issue of Circuit Cellar is coming next week! What’s coming up in October Circuit Cellar? Technology for Smart Cities, LoRa, stub filters, Raspberry Pi, embedded PCs, fun MCU-based projects, color temperature and more!!—this 84-page magazine invites you into our busting virtual downtown of quality-built embedded technology articles for your reading delight.
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Here’s a sneak preview of October 2020 Circuit Cellar:
TECHNOLOGIES FOR A CONNECTED WORLD

Technologies for Smart Cities
By Jeff Child
Huge opportunities exist today for implementing systems that build today’s Smart Cities. From controlling energy waste to Smart Lighting and traffic control, IoT technologies including sensors, microcontrollers, analog ICs and wireless connectivity products all have roles to play in Smart Cities. Circuit Cellar Chief Editor Jeff Child looks at these technology trends.
LoRa (Part 7): Building a Prototype LoRa Device
By Bob Japenga
Bob wraps up his article series on LoRa. In the previous two articles, Bob examined MachineQ resources for LoRa development. Here, in Part 7, Bob explores creating a prototype sensor for the MachineQ network.
Design a Wireless Tracking Device
By Geoff Schulteis
Portable trackers offer a very particular set of problems for designers. In this article, Antenova’s Geoff Schulteis takes a quick look at the design requirements of a portable tracking device, the choice of embedded antennas and some of the points to consider when designing a product where the performance of the antenna in situ could determine the commercial success of the product.
Intro to Stub Filters: A Wire to Nowhere
By Robert Lacoste
Wires—either as cabling or PCB traces—connecting components are fundamental to any electronic system. But wires that go to nowhere, called stub filters, can have a useful role as well. In this article, Robert tells you helps you understand and build stub filters, but also explains the dangers of accidentally including a stub filter in your PCB design.
RESOURCES FOR EMBEDDED ENGINEERS
Datasheet: Embedded PCs
By Jeff Child
Gone are the days when box-level embedded computers, also known as Embedded PCs, were strictly custom-built offerings. Today, several vendors offer extensive product lines of embedded PC of all sizes and configurations, and for diverse applications from vehicle computing to digital signage. This Datasheet section updates readers on these trends and provides a product album of representative of embedded PC systems.
A Review: V5 Plus Drone Flight Controller
By Raul Alvarez-Torrico
Over the past year, Raul has written several articles about drone design. Here, he offers a product review of CUAV Tech’s V5 Plus drone flight controller and its associated NEO V2 GNSS module. Raul dives into specifications and functions of these device in great detail, then shares the results of some flight tests using the products.
Raspberry Pi Roundup
By Jeff Child
While basically the most popular SBC among hobbyists, professional engineers are seeing the value of Raspberry Pi’s growing ecosystem of products. Raspberry Pi HATs (Hardware Attached on Top), add-on boards for Raspberry Pi SBCs, of all kinds have emerged over the past six years targeting everything from data acquisition to air quality measurement. Circuit Cellar Chief Editor Jeff Child delves into the latest technology trends and product developments in Raspberry Pi products.
Building a Power Rail Probe
By Andrew Levido
A power rail probe is a special oscilloscope probe designed specifically to help probe DC power rails. Most of the larger oscilloscope manufacturers offer them if you are prepared to shell out a couple of thousand dollars. In this project article, Andrew sets out to see if he could build one with comparable performance, but for a lot less money.
DEEP DIVES INTO KEY TECHNICAL CONCEPTS
White Hot: Measuring Color Temperature
By Jeff Bachiochi
Centuries before the science of color temperature was understood, blacksmiths have known how to read the temperature of heated metal by its color emissions. In this article, Jeff discusses the math and science behind color temperature. He then details his project that uses a color-light-to-digital sensor to measure the color temperature of a light source.
Code Size vs. Memory Footprint
By Steve Graves
The terms “code size” and “footprint” are often used interchangeably. But they are not the same—code size is a subset of footprint. In this article, McObject CEO Steve Graves explains the differentiation and relevance. He then describes some techniques to minimize footprint.
Balancing a Ball on a Touchscreen
By Gregory Kaiser and Sam Feibel
Servo control is just one area where MCUs shine. In this article, see how these two Cornell students designed and built a PIC32 MCU-based ball-balancing platform using a resistive touchscreen and servo motors attached to a gimbaled mount. A PID control algorithm is used to balance the ball.