Highly Integrated, Precision ADCs and DACs Feature Small Footprint

Texas Instruments (TI) has introduced four tiny precision data converters. The new data converters enable designers to add more intelligence and functionality, while shrinking system board space. The DAC80508 and DAC70508 are eight-channel precision digital-to-analog converters (DACs) that provide true 16- and 14-bit resolution, respectively. The ADS122C04 and ADS122U04 are 24-bit precision analog-to-digital converters (ADCs) that feature a two-wire, I2C-compatible interface and a two-wire, UART-compatible interface, respectively. The devices are optimized for a variety of small-size, high-performance or cost-sensitive industrial, communications and personal electronics applications. Examples include optical modules, field transmitters, battery-powered systems, building automation and wearables.

Both DACs include a 2.5-V, 5-ppm/°C internal reference, eliminating the need for an external precision reference. Available in a 2.4-mm-by-2.4-mm die-size ball-grid array (DSBGA) package or wafer chip-scale package (WCSP) and a 3-mm-by-3-mm quad flat no-lead (QFN)-16 package, these devices are up to 36 percent smaller than the competition. The new DACs eliminate the typical trade-off between high performance and small size, enabling engineers to achieve the best system accuracy, while reducing board size or increasing channel density.

In addition to their compact size, the DAC80508 and DAC70508 provide true, 1 least significant bit (LSB) integral nonlinearity to achieve the highest level of accuracy at 16- and 14-bit resolution – up to 66 percent better linearity than the competition. They are fully specified over a -40°C to +125°C extended temperature range and provide features such as cyclic redundancy check (CRC) to increase system reliability.

The tiny, 24-bit precision ADCs are available in 3-mm-by-3-mm very thin QFN (WQFN)-16 and 5-mm-by-4.4-mm thin-shrink small-outline package (TSSOP)-16 options. The two-wire interface requires fewer digital isolation channels than a standard serial peripheral interface (SPI), reducing the overall cost of an isolated system. These precision ADCs eliminate the need for external circuitry by integrating a flexible input multiplexer, a low-noise programmable gain amplifier, two programmable excitation current sources, an oscillator and a precision temperature sensor.

Both ADC devices feature a low-drift 2.048-V, 5-ppm/°C internal reference. Their internal 2 percent accurate oscillators help designers improve power-line cycle noise rejection, enabling higher accuracy in noisy environments. With gains from 1 to 128 and noise as low as 100 nV, designers can measure both small-signal sensors and wide input ranges with one ADC. These device families, which also include pin-to-pin-compatible 16-bit options, give designers the flexibility to meet various system requirements by scaling performance up or down.

Engineers can evaluate the new data converters with the DAC80508 evaluation module, the ADS122C04 evaluation module and the ADS122U04 evaluation module, all available today for $99.00 from the TI store and authorized distributors.

TI’s new tiny DACs and ADCs are available now with pricing ranging from $3.95 to $9.99 (1,000s).

Texas Instruments | www.ti.com

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TECHNOLOGIES FOR THE INTERNET-OF-THINGS

Wireless Standards and Solutions for IoT  
One of the critical enabling technologies making the Internet-of-Things possible is the set of well-established wireless standards that allow movement of data to and from low-power edge devices. Here, Circuit Cellar’s Editor-in-Chief, Jeff Child, looks at key wireless standards and solutions playing a role in IoT.

Product Focus: IoT Device Modules
The rapidly growing IoT phenomenon is driving demand for highly integrated modules designed to interface with IoT devices. This Product Focus section updates readers on this technology trend and provides a product album of representative IoT interface modules.

TOOLS AND TECHNIQUES AT THE DESIGN PHASE

EMC Analysis During PCB Layout
If your electronic product design fails EMC compliance testing for its target market, that product can’t be sold. That’s why EMC analysis is such an important step. In his article, Mentor Graphics’ Craig Armenti shows how implementing EMC analysis during the design phase provides an opportunity to avoid failing EMC compliance testing after fabrication.

Extreme Low-Power Design
Wearable consumer devices, IoT sensors and handheld systems are just a few of the applications that strive for extreme low-power consumption. Beyond just battery-driven designs, today’s system developers want no-battery solutions and even energy harvesting. Circuit Cellar’s Editor-in-Chief, Jeff Child, dives into the latest technology trends and product developments in extreme low power.

Op Amp Design Techniques
Op amps can play useful roles in circuit designs linking the real analog world to microcontrollers. Stuart Ball shares techniques for using op amps and related devices like comparators to optimize your designs and improve precision.

Wire Wrapping Revisited
Wire wrapping may seem old fashioned, but this tried and true technology can solve some tricky problems that arise when you try to interconnect different kinds of modules like Arduino, Raspberry Pi and so on. Wolfgang Matthes steps through how to best employ wire wrapping for this purpose and provides application examples.

DEEP DIVES ON MOTOR CONTROL AND MONITORING

BLDC Fan Current
Today’s small fans and blowers depend on brushless DC (BLDC) motor technology for their operation. In this article, Ed Nisley explains how these seemingly simple devices are actually quite complex when you measure them in action. He makes some measurements on the motor inside a tangential blower and explores how the data relates to the basic physics of moving air.

Electronic Speed Control (Part 1)
An Electronic Speed Controller (ESC) is an important device in motor control designs, especially in the world of radio-controlled (RC) model vehicles. In Part 1, Jeff Bachiochi lays the groundwork by discussing the evolution of brushed motors to brushless motors. He then explores in detail the role ESC devices play in RC vehicle motors.

MCU-Based Motor Condition Monitoring
Thanks to advances in microcontrollers and sensors, it’s now possible to electronically monitor aspects of a motor’s condition, like current consumption, pressure and vibration. In this article, Texas Instrument’s Amit Ashara steps through how to best use the resources on an MCU to preform condition monitoring on motors. He looks at the signal chain, connectivity issues and A-D conversion.

AND MORE FROM OUR EXPERT COLUMNISTS

Verifying Code Readout Protection Claims
How do you verify the security of microcontrollers? MCU manufacturers often make big claims, but sometimes it is in your best interest to verify them yourself. In this article, Colin O’Flynn discusses a few threats against code readout and looks at verifying some of those claimed levels.

Thermoelectric Cooling (Part 1)
When his thermoelectric water color died prematurely, George Novacek was curious whether it was a defective unit or a design problem. With that in mind, he decided to create a test chamber using some electronics combined with components salvaged from the water cooler. His tests provide some interesting insights into thermoelectric cooling.

 

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PCB DESIGN AND POWER: MAKING SMART CHOICES

PCB Design and Verification
PCB design tools and methods continue to evolve as they race to keep pace with faster, highly integrated electronics. Automated, rules-based chip placement is getting more sophisticated and leveraging AI in interesting ways. And supply chains are linking tighter with PCB design processes. Circuit Cellar Chief Editor Jeff Child looks at the latest PCB design and verification tools and technologies.

PCB Ground Planes
Tricky design decisions crop up when you’re faced with crafting a printed circuit board (PCB) for any complex system—and many of them involve the ground plane. There is dealing with noisy components and deciding between a common ground plane or separate ones—and that’s just the tip of the iceberg. Robert Lacoste shares his insights on the topic, examining the physics, simulation tools and design examples of ground plane implementations.

Product Focus: AC-DC Converters
To their peril, embedded system developers often treat their choice of power supply as an afterthought. But choosing the right AC-DC converter is critical to the ensuring your system delivers power efficiently to all parts of your system. This Product Focus section updates readers on these trends and provides a product album of representative AC-DC converter products.

SENSORS TAKE MANY FORMS AND FUNCTIONS

Sensors and Measurement
While sensors have always played a key role in embedded systems, the exploding Internet of Things (IoT) phenomenon has pushed sensor technology to the forefront. Any IoT implementation depends on an array of sensors that relay input back to the cloud. Circuit Cellar Chief Editor Jeff Child dives into the latest technology trends and product developments in sensors and measurement.

Passive Infrared Sensors
One way to make sure that lights get turned off when you leave a room is to use Passive Infrared (PIR) sensors. Jeff Bachiochi examines the science and technology behind PIR sensors. He then details how to craft effective program code and control electronics to use PIR sensors is a useful way.

Gesture-Recognition in Boxing Glove
Learn how two Boston University graduate students built a gesture-detection wearable that acts as a building block for a larger fitness telemetry system. Using a Linux-based Gumstix Verdex, the wearable couples an inertial measurement unit with a pressure sensor embedded in a boxing glove to recognize the user’s hits and classify them according to predefined, user-recorded gestures.

SECURITY, RELIABILITY AND MORE

Internet of Things Security (Part 3)
In this next part of his article series on IoT security, Bob Japenga looks at the security features of a specific series of microprocessors: Microchip’s SAMA5D2. He examines these security features and discusses what protection they provide.

Aeronautical Communication Protocols
Unlike ground networks, where data throughout is the priority, avionics networks are all about reliability. As a result, the communications protocols used in for aircraft networking seem pretty obscure to the average engineer. In this article, George Novacek reviews some of the most common aircraft comms protocols including ARINC 429, ARINC 629 and MIL-STD-1553B

DEEP DIVES ON PROCESSOR DESIGN AND DIGITAL SIGNAL PROCESSING

Murphy’s Laws in the DSP World (Part 1)
A Pandora’s box of unexpected issues gets opened the moment you move from the real world of analog signals and enter the world of digital signal processing (DSP). In Part 1 of this new article series, Mike Smith defines six “Murphy’s Laws of DSP” and provides you with methods and techniques to navigate around them.

Processor Design Techniques and Optimizations
As electronics get smaller and more complex day by day, knowing the basic building blocks of processors is more important than ever. In this article, Nishant Mittal explores processor design from various perspectives—including architecture types, pipelining and ALU varieties.

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NAVIGATING THE INTERNET-OF-THINGS

IoT: From Gateway to Cloud
In this follow on to our March “IoT: Device to Gateway” feature, this time we look at technologies and solutions for the gateway to cloud side of IoT.  Circuit Cellar Chief Editor Jeff Child examines the tools and services available to get a cloud-connected IoT implementation up and running.

Texting and IoT Embedded Devices (Part 2)
In Part 1, Jeff Bachiochi laid the groundwork for describing a project involving texting. He puts that into action this, showing how to create messages on his Espressif System’s ESP8266EX-based device to be sent to an email account and end up with those messages going as texts to a cell phone.

Internet of Things Security (Part 2)
In this next part of his article series on IoT security, Bob Japenga takes a look at side-channel attacks. What are they? How much of a threat are they? And how can we prevent them?

Product Focus: 32-Bit Microcontrollers
As the workhorse of today’s embedded systems, 32-bit microcontrollers serve a wide variety of embedded applications—including the IoT. This Product Focus section updates readers on these trends and provides a product album of representative 32-bit MCU products.

GRAPHICS, VISION AND DISPLAYS

Graphics, Video and Displays
Thanks to advances in displays and innovations in graphics ICs, embedded systems can now routinely feature sophisticated graphical user interfaces. Circuit Cellar Chief Editor Jeff Child dives into the latest technology trends and product developments in graphics, video and displays.

Color Recognition and Segmentation in Real-time
Vision systems used to require big, multi-board systems—but not anymore. Learn how two Cornell undergraduates designed a hardware/software system that accelerates vision-based object recognition and tracking using an FPGA SoC. They made a min manufacturing line to demonstrate how their system can accurately track and categorize manufactured candies carried along a conveyor belt.

SPECIFICATIONS, QUALIFICATIONS AND MORE

Component tolerance
We perhaps take for granted sometimes that the tolerances of our electronic components fit the needs of our designs. In this article, Robert Lacoste takes a deep look into the subject of tolerances, using the simple resistor as an example. He goes through the math to help you better understand accuracy and drift along with other factors.

Understanding the Temperature Coefficient of Resistance
Temperature coefficient of resistance (TCR) is the calculation of a relative change of resistance per degree of temperature change. Even though it’s an important spec, different resistor manufacturers use different methods for defining TCR. In this article, Molly Bakewell Chamberlin examines TCR and its “best practice” interpretations using Vishay Precision Group’s vast experience in high-precision resistors.

Designing of Complex Systems
While some commercial software gets away without much qualification during development, the situation is very different when safety in involved. For aircraft, vehicles or any complex system where failure unacceptable, this means adhering to established standards throughout the development life cycle. In this article, George Novacek tackles these issues and examines some of these standards namely ARP4754.

AND MORE IN-DEPTH PROJECT ARTICLES

Build a Marginal Oscillator Proximity Switch
A damped or marginal oscillator will switch off when energy is siphoned from its resonant LC tank circuit. In his article, Dev Gualtieri presents a simple marginal oscillator that detects proximity to a small steel screw or steel plate. It lights an LED, and the LED can be part of an optically-isolated solid-state relay.

Obsolescence-Proof Your UI (Part 1)
After years of frustration dealing with graphical interface technologies that go obsolete, Steve Hendrix decided there must be a better way. Knowing that web browser technology is likely to be with us for a long while, he chose to build a web server that could perform common operations that he needed on the IEEE-488 bus. He then built it as a product available for sale to others—and it is basically obsolescence-proof.

 

 

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TECHNOLOGY FOR THE INTERNET-OF-THINGS

IoT: From Device to Gateway
The Internet of Things (IoT) is one of the most dynamic areas of embedded systems design today. This feature focuses on the technologies and products from edge IoT devices up to IoT gateways. Circuit Cellar Chief Editor Jeff Child examines the wireless technologies, sensors, edge devices and IoT gateway technologies at the center of this phenomenon.

Texting and IoT Embedded Devices
Texting has become a huge part of our daily lives. But can texting be leveraged for use in IoT Wi-Fi devices? Jeff Bachiochi lays the groundwork for describing a project that will involve texting. In this part, he gets into out the details for getting started with a look at Espressif System’s ESP8266EX SoC.

Exploring the ESP32’s Peripheral Blocks
What makes an embedded processor suitable as an IoT or home control device? Wi-Fi support is just part of the picture. Brian Millier has done some Wi-Fi projects using the ESP32, so here he shares his insights about the peripherals on the ESP32 and why they’re so powerful.

MICROCONTROLLERS HERE, THERE & EVERYWHERE

Designing a Home Cleaning Robot (Part 4)
In this final part of his four-part article series about building a home cleaning robot, Nishant Mittal discusses the firmware part of the system and gets into the system’s actual operation. The robot is based on Cypress Semiconductor’s PSoC microcontroller.

Apartment Entry System Uses PIC32
Learn how a Cornell undergraduate built a system that enables an apartment resident to enter when keys are lost or to grant access to a guest when there’s no one home. The system consists of a microphone connected to a Microchip PIC32 MCU that controls a push solenoid to actuate the unlock button.

Posture Corrector Leverages Bluetooth
Learn how these Cornell students built a posture corrector that helps remind you to sit up straight. Using vibration and visual cues, this wearable device is paired with a phone app and makes use of Bluetooth and Microchip PIC32 technology.

INTERACTING WITH THE ANALOG WORLD

Product Focus: ADCs and DACs
Makers of analog ICs are constantly evolving their DAC and ADC chips pushing the barriers of resolution and speeds. This new Product Focus section updates readers on this technology and provides a product album of representative ADC and DAC products.

Stepper Motor Waveforms
Using inexpensive microcontrollers, motor drivers, stepper motors and other hardware, columnist Ed Nisley built himself a Computer Numeric Control (CNC) machines. In this article Ed examines how the CNC’s stepper motors perform, then pushes one well beyond its normal limits.

Measuring Acceleration
Sensors are a fundamental part of what make smart machines smart. And accelerometers are one of the most important of these. In this article, George Novacek examines the principles behind accelerometers and how the technology works.

SOFTWARE TOOLS AND PROTOTYPING

Trace and Code Coverage Tools
Today it’s not uncommon for embedded devices to have millions of lines of software code. Trace and code coverage tools have kept pace with these demands making it easier for embedded developers to analyze, debug and verify complex embedded software. Circuit Cellar Chief Editor Jeff Child explores the latest technology trends and product developments in trace and code coverage tools.

Manual Pick-n-Place Assembly Helper
Prototyping embedded systems is an important part of the development cycle. In this article, Colin O’Flynn presents an open-source tool that helps you assemble prototype devices by making the placement process even easier.

Gas Monitoring and Sensing (Part 1)

Fun with Fragrant Analysis

Gas sensing technology has come long way since the days of canaries in coal mines. This month columnist Jeff covers the background issues surrounding gas monitoring and sensing. Then he describes how he uses sensors, A/D conversion and Arduino technologies to do oxygen measurement.

By Jeff Bachiochi

When coal miners began dropping like flies, it was determined that poisonous gas was the culprit. To date there was no test to detect the presence of this odorless ghost. Sacrificial canaries became the guinea pigs, giving up their lives to save the miners. These birds are especially sensitive to methane and carbon monoxide. When the song bird stopped singing, miners headed for a breath of fresh air until the mine could be cleared of the silent killer.

Seemingly ripe for disaster, the flame height of an oil lamp was used for detecting dangerous conditions in the 1800s. A shrinking flame indicated reduced oxygen, while a stronger flame indicated the presence of methane—or other combustible gas. Flame arrestors kept the combustion internal to the lamp, preventing external gas ignition unless it was dropped.

In the 1900s, it was discovered that the current through an electric heater was affected when nearby combustible gases increased in temperature. The use of a catalytic material—such as palladium—lowers the temperature at which combustion takes place. Using these heaters in a Whetstone bridge configuration—where one leg is exposed to the gas—can create an easily measured imbalance proportional to the concentration of the combustible gas.

Infrared light can be used to measure the concentration of many hydrocarbon gases. When compared to a gas-free path, the IR absorption through a gas can indicate the concentration of hydrocarbon molecules. Gases can be identified by their molecular makeup. That is the amount of each element present. Absorption bands can be identified by dispersion through diffraction or non-dispersion through filtration. Concentration is the relationship of a particular wavelength between a reference path and a gas absorption path.

Table Untitled

This summary of the basic gas sensing methods includes their advantages, disadvantages and general areas of use. (Source: www.equipcoservices.com/support/reference/ionization-potentials-of-common-chemicals),

There are many techniques available today for monitoring gases. Refer to Table 1 for a breakdown of gas monitoring methods and their associated advantages and disadvantages. HAZMAT Class 2 in United States identifies all gases which can be compressed and stored for transportation. Even though we are not directly dealing with storage or transportation, the class is further defined by three groups of gases: flammable, toxic and others (non-flammable).

Read the full article in the October 327 issue of Circuit Cellar

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