USB Data Acq System Features Simple Expansion

DATAQ Instruments has announced the release of its model DI-2108-P USB data acquisition (DAQ) system with 16-bit ADC resolution, programmable gain and ChannelStretch technology. The model DI-2108-P provides eight analog input channels each with 2.5-, 5- and 10-volt unipolar and bi-polar programmable measurement ranges. DATAQ Instruments di2108-product-photo-press-releaseThe DI-2108-P also provides 7 digital ports, each configurable as an input or a switch. Two ports can be programmed as counter and frequency measurement inputs. The instrument’s maximum sampling throughput rate is 160 kHz.

The ChannelStretch feature of the DI-2108-P makes channel expansion as easy as adding another device. Plug a second device into a computer and double the channel count of both analog and digital channels. Using USB hubs, plug up to sixteen devices into a single PC for a maximum count of 128 analog and 112 digital channels. And all of them are acquired synchronously at a maximum sample throughput rate of at least 480 kHz. DI-2108-P software support includes ready-to run WinDaq data acquisition software, .Net class, ActiveX controls and a fully documented communication protocol to deploy the instrument on any platform. The unit is priced at $349.

DATAQ Instruments | www.dataq.com

October Circuit Cellar: A Sneak Preview

The October issue of Circuit Cellar magazine is on the launch pad, ready to deliver a selection of excellent embedded electronics articles covering trends, technology and design.

Not a Circuit Cellar subscriber?  Don’t be left out! Sign up today:

 

Here’s a sneak preview of October Circuit Cellar:

TECHNOLOGY FOR DRONES / ROBOTIC HAND

Commercial Drone Design Solutions Take Flight: Chips, Boards and Platforms
The control, camera and comms electronics inside today’s drones have to pack in an ambitious amount of functionality. Circuit Cellar Chief Editor Jeff Child explores the latest Oct 327 Coverand greatest chip and module solutions serving today’s commercial and consumer drone designs.

Building a Robot Hand: With Servos and Electromyography
Learn how three Cornell University students developed a robotic hand. The system captures impulses generated by muscle contractions and then filters and feeds those signals to a microcontroller which controls finger movement.

 

CAN’T STOP THE SIGNAL

Signal Chain Tech Pushes Bandwidth Barriers: ADCs, FPGAs and DACs
FPGAs and D-A converters are key  technologies making up a signal chain. Here, Circuit Cellar Chief Editor Jeff Child steps through the state-of-the-art options available for crafting efficient, highly-integrated signal-centric systems.

Antenna Performance Measurement Made Easy: Covering the Basics
If you’re doing any kind of wireless communications design, chances are you’re including an antenna. Columnist Robert Lacoste shows how the task of measuring an antenna’s performance is less costly and exotic than you’d think.

MONITORING GEAR WITH MICROCONTROLLER BRAINS

Gas Monitoring and Sensing (Part 1): Fun with Fragrant Analysis
Columnist Jeff Bachiochi 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.

Logger Device Tracks Amp Hours (Part 1): Measuring Home Electricity
Setting out to monitor and log electricity usage in his house, Bill Wachsmann built an amp-hour logger using a microcontroller and a clamp on ammeter.

KEEPING THE LEGACY ALIVE

Emulating Legacy Interfaces: Do it with Microcontrollers
There’s a number of important legacy interface technologies—like ISA and PCI—that are no longer supported by the mainstream computing industry. In his article Wolfgang Matthes examines ways to use microcontrollers  to emulate the bus signals of legacy interconnect schemes.

Building a Retro TV Remote : PIC MCU-Based Design
Dev Gualtieri embarks on building a retro-style TV remote, based on a Microchip PIC microcontroller. He outlines the phototransistor, battery and software designs he made along the way.

AND MORE FROM OUR EXPERT COLUMNISTS:

Get in the Loop on Positive Feedback: New Value in an Old Concept
Positive feedback loops are an important element of modern circuitry such as crystal oscillators, PLLs and other devices. Here, George Novacek goes deep into the math and circuit analysis of positive feedback and how it’s used in electronics.

Build an Embedded Systems Consulting Company (Part 6): Trade-Offs of Fixed-Price Contracts
Continuing his “Building an Embedded Systems Consulting Company” article series, this month Bob Japenga explores the nature of contracts and how fixed price contracts can be an effective, albeit dangerous tool in marketing.

September Circuit Cellar: A Sneak Preview

The September (326) issue of Circuit Cellar magazine serves up a meaty selection of useful technology resources along with inspiring, interesting embedded electronics design articles.

Not a Circuit Cellar subscriber?  Don’t be left out! Sign up today:

cclogo_2013_header

Here’s a sneak preview of September Circuit Cellar:

FOCUS ON MICROCONTROLLERS

Getting Started with PSoC Microcontrollers (Part 3): Data Conversion, Capacitive Sensing and More
In Part 3, Nishant Mittal gets into some if the PSoC’s more complex features like Data Conversion.

Implementing a Time-Oriented Task Manager for 8-bit PIC Microcontrollers
Pedro Bertoleti shows readers how to build a time-oriented task manager using Microchip’s PIC 16F628A 8-bit microcontroller.

SPECIAL SECTION: EMBEDDED SECURITY

Microcontrollers Beef Up Security Features: Defense in a Connected World
Jeff Child explores the various flavors of embedded security features that microcontroller vendors are adding to their devices.

Resources for Embedded Security: Hardware, Software and Services
Circuit Cellar collects four pages worth of info about companies that provide embedded security products, tools and services.

TECHNOLOGY FEATURES

Using Power Audio Amplifiers in Untypical Ways (Part 1): Best Building Blocks
Petre Petrov shows readers how to use PAAs as universal building blocks to create analog signal generators, analog power supplies, voltage splitters and more.

Data Acquisition Advances Focus on Interfacing
Jeff Child discusses the latest data acquisition solutions, with a look at how interface technologies have evolved.

Future of IoT Communications: Will Upgraded Cellular Networks Benefit IoT?
This guest essay by Andrew Girson, CEO of Barr Group, explores how IoT will fare in the 5G network era.

MORE FROM OUR EXPERT COLUMNISTS:

Block Diagram Reduction and Automatic Tuning
George Novacek steps through how to think in terms of block diagrams to help you reduce system complexity early on in a design.

Numeric Precision vs. DDS Calculations
Using the full frequency resolution of a DDS chip outstrips the capabilities of floating point numbers. Ed Nisley looks at high-res frequency calibration and measurements in the DDS realm.

Deadbolt the Uninvited: Locked Out of My Home
In this Part 2 of Jeff Bachiochi’s electronic lock story, he gets into some of the power and remote-control issues of his electronic deadbolt lock project.

Diagnosing Performance Variations in HPC
Ayse K. Coskun delves into how application performance variations can cause inefficiency
in high-performance computing (HPC) systems and how to diagnose these variations.

Software Targets Data Acq for Desktop Python under Linux

Microstar Laboratories has released DAPtools for Python software, an API that enables high-performance data acquisition applications using the Python programming language on desktop GNU/Linux systems. This is not a reduced or specialized language variant—it supports the complete, full-featured Python environment and complements the Accel64 for Linux software that provides access to DAP board features and functions. Typical applications are one-time diagnostic tests, academic research, and automatically-configurable scripting for test automation.

MicroStar

The DAPIO programming interface behind DAPtools for Python provides the same stable DAPL system services that all other high-level programming environments have used over the last 20 years. Access to that interface is through a Linux dynamic library, which Python applications can load and access using the ctypes library. DAPtools for Python presents the low-level interface as a simple “interface object” and some utility functions to make the DAP board interactions work like familiar Python objects and functions. The programming is a lot like connecting to a networked resource: open a connection, specify the data acquisition actions required, run the configuration, take the requested data, and close the connection when finished.

Microstar Laboratories | www.mstarlabs.com

August Circuit Cellar: A Sneak Preview

The August (325) issue of Circuit Cellar magazine is jammed packed with useful technical information and inspiring, intriguing embedded electronics design stories.

Not a Circuit Cellar subscriber?  Don’t be left out! Sign up today:

 

Here’s a sneak preview of August Circuit Cellar:

FUN WITH GUITAR AMPLIFIERS!

Digital Guitar Amplifier/ Effects Processor—Part 2
Brian Millier details the digital guitar amplifier/effects unit he built using two Teensy Arduino modules.

A Range of Power Supplies for Hollow-State Guitar Amplifiers
Richard Honeycutt compares several different power supplies used for hollow-state guitar amplifiers.

MICROCONTROLLERS & PROCESSORS!

Firmware Upgrade with the PIC32
Nick Sicalides delves into performing firmware upgrades using a bootloader on the Microchip PIC32

Getting Started with PSoC Microcontrollers (Part 2): Putting PSoC to Work
Nishant Mittal goes even deeper on the Cypress PSoC providing some useful design examples.

Moore’s Law and the Chip Industry’s Perfect Storm
In this Interview Q&A Krste Asanovic explains RISC-V and the open sourcing of processor architecture.

SECURITY & RELIABILITY & ENCRYPTION!

Power Analysis of a Software DES Encryption Routine
Columnist Colin O’Flynn examines how to break a software implementation of the DES security routine.

Reliability and Failure Prediction: A New Take
Craig Armenti and Dave Wiens discuss a better way to simulate PCB vibration and acceleration.

Preventing Unwanted Entry
Columnist Jeff Bachiochi takes us inside his exploration of electronic lock systems, getting down to the fine details.

Future of Embedded Security: Wi-Fi to the Danger Zone
This guest essay by Adam Cecchetti, CEO of Deja vu Security, explains how memory leaks in your embedded system could have life or death consequences.

AND MORE FROM OUR EXPERT COLUMNISTS:

Automatic Control (Part 4) The Implementation
George Novacek describes the PID temperature controller he built for a meat smoker.

Fully Differential Amplifiers
Robert Lacoste sings the praises of fully differential amplifiers and presents a few designs using them.

Build an Embedded Systems Consulting Company (Part 5) Axiom Wrap-Up
Bob Japenga shares more insights on running a successful embedded design firm built to last.

Accel32 for Linux Software Supports 4.xx Kernel

Microstar Laboratories recently released version 3.00 of the Accel32 for Linux software. The software compiles a Loadable Kernel Module (LKM) for the GNU/Linux system, extending capabilities for control of the Data Acquisition Processor (DAP) boards to systems using GNU/Linux operating systems with kernel versions in the 4.xx series.

Photo caption: Real time acquisition on generic platforms: Accel32 for Linux v.3.0 supports GNU/Linux 4.xx kernels. Penguin: Julien Tromeur/Shutterstock.com

Real-time acquisition on generic platforms: Accel32 for Linux v.3.0 supports GNU/Linux 4.xx kernels. Penguin: Julien Tromeur/Shutterstock.com

Accel32 for Linux is offered under the BSD license for free download. DAP boards provide an Intel x86-family embedded processor to support operation of the embedded DAPL 2000 system and data acquisition hardware devices. The DAPL 2000 system is part of the DAPtools software, which Microstar Laboratories provides for free for operating the DAP boards. The DAPL 2000 system provides the configuration scripting and the multitasking real-time control of data acquisition hardware devices. A host system must provide PCI or PCI-X (extended) I/O bus slots to host the DAP boards. This software runs under 32-bit versions of the GNU/Linux system, which you can install on 32- or 64-bit hardware platforms.

Source: Microstar Laboratories

Data Acquisition Issues (2 Free Downloads)

As Maurizio Di Paolo Emilio noted in his essay “The Future of Data Acquisition,” data acquisition “is a necessity, which is why data acquisition systems and software applications are essential tools in a variety of fields.”

For a limited time, we’re sharing two past Circuit Cellar Data Acquisition issues (CC266 and CC278), which you can download for free. These two free downloads will be available only until Friday, September 19.

 

Issue #266 September 2012

  • TASK MANAGER—The Ubiquitous Importance of Data, p. 2
  • QUESTIONS & ANSWERS—Embedded Systems Education: An Interview with Miguel Sánchez, p. 28
  • MCU-Based Environmental Data Logger, by Brian Beard, p. 18
  • DesignSpark chipKIT Challenge Winners, p. 32
  • Miniature Accelerometers: DIY Acceleration Data Acquisition, by Mark Csele, p. 38
  • EMBEDDED SECURITY—Hardware-Accelerated Encryption, by Patrick Schaumont, p. 48
  • THE CONSUMMATE ENGINEER—Project Configuration Control: Family Tree Drawing & Document Archiving, by George Novacek, p. 58
  • LESSONS FROM THE TRENCHES—Software & Design File Organization, by George Martin, p. 62
  • FROM THE BENCH—Flowcharting Made Simple: Use the Flowcode Flowcharting IDE to Write Code, by Jeff Bachiochi, p. 66
  • PRIORITY INTERRUPT—Managing Expectations, by Steve Ciarcia, p. 80

Issue #278 September 2013

  • QUESTIONS & ANSWERS—Electronics Entrepreneur: An Interview with Jack Ganssle, p. 10
  • Rubik’s Cube-Solving Robot, by Nelson Epp, p. 24
  • Raspberry Pi I/0 Board (Part 2): ISO-Pi Circuit Description and Firmware, by Brian Millier, p. 32
  • Experiments in Developmental Robotics (Part 1): Artificial and Evolving Neural Networks, by Walter O. Krawec, p. 42
  • THE CONSUMMATE ENGINEER—Battery Basics (Part 1): Battery Types, by George Novacek, p. 48
  • ABOVE THE GROUND PLANE—Pulsed LED Characterization, by Ed Nisley, p. 54
  • GREEN COMPUTING—Energy-Efficient Cooling Strategies for Servers Analyze and Control Leakage and Fan Power, by Ayse Coskun, p. 60
  • FROM THE BENCH—Serial Displays Save Resources (Part 3): BMP Files, by Jeff Bachiochi, p. 64
  • TECH THE FUTURE—Electronics Beyond Silicon, by Jeremy Ward and Oana Jerchescu, p. 80

Flexible I/O Expansion for Rugged Applications

WynSystemsThe SBC35-CC405 series of multi-core embedded PCs includes on-board USB, gigabit Ethernet, and serial ports. These industrial computers are designed for rugged embedded applications requiring extended temperature operation and long-term availability.

The SBC35-CC405 series features the latest generation Intel Atom E3800 family of processors in an industry-standard 3.5” single-board computer (SBC) format COM Express carrier. A Type 6 COM Express module supporting a quad-, dual-, or single-core processor is used to integrate the computer. For networking and communications, the SBC35-CC405 includes two Intel I210 gigabit Ethernet controllers with IEEE 1588 timestamping and 10-/100-/1,000-Mbps multispeed operation. Four Type-A connectors support three USB 2.0 channels and one high-speed USB 3.0 channel. Two serial ports support RS-232/-422/-485 interface levels with clock options up to 20 Mbps in the RS-422/-485 mode and up to 1 Mbps in the RS-232 mode.

The SBC35-CC405 series also includes two MiniPCIe connectors and one IO60 connector to enable additional I/O expansion. Both MiniPCIe connectors support half-length and full-length cards with screw-down mounting for improved shock and vibration durability. One MiniPCIe connector also supports bootable mSATA solid-state disks while the other connector includes USB. The IO60 connector provides access to the I2C, SPI, PWM, and UART signals enabling a simple interface to sensors, data acquisition, and other low-speed I/O devices.

The SBC35-CC405 runs over a 10-to-50-VDC input power range and operates at temperatures from –40°C to 85°C. Enclosures, power supplies, and configuration services are also available.

Linux, Windows, and other x86 OSes can be booted from the CFast, mSATA, SATA, or USB interfaces, providing flexible data storage options. WinSystems provides drivers for Linux and Windows 7/8 as well as preconfigured embedded OSes.
The single-core SBC35-CC405 costs $499.

Winsystems, Inc.
www.winsystems.com

Integrated Wi-Fi System in Package Module

EconaisThe EC19W01 is a small, smart, highly integrated 802.11b/g/n Wi-Fi system in package (SiP) module. The module is well suited for home automation and smart appliances; Wi-Fi audio speakers and headphones; wireless sensors and sensor networks; wireless monitoring (audio and video); smart appliances; health care and fitness devices; wearable devices; security, authentication, and admittance control; lighting; building/energy/industrial management/control; cloud-connected devices; remote control, data acquisition, and monitoring; and machine-to-machine (M2M) and Internet of Things (IoT) design.

The EC19W01’s features include an integrated 32-bit processor to support application customization, on-board flash and antenna, low power consumption, support for Serial-to-Wi-Fi and SPI-to-Wi-Fi, wireless transmit/receive rates of up to 20 Mbps, and a small 14-mm × 16-mm × 2.8-mm footprint.

Contact Econais for pricing.

Econais, Inc.
www.econais.com

PC-Programmable Temperature Controller

Oven Industries 5R7-388 temperature controller

Oven Industries 5R7-388 temperature controller

The 5R7-388 is a bidirectional temperature controller. It can be used in independent thermoelectric modules or in conjunction with auxiliary or supplemental resistive heaters for cooling and heating applications. The solid-state MOSFET output devices’ H-bridge configuration enables the bidirectional current flow through the thermoelectric modules.
The RoHS-compliant controller is PC programmable via an RS-232 communication port, so it can directly interface with a compatible PC. It features an easily accessible communications link that enables various operational mode configurations. The 5R7-388 can perform field-selectable parameters or data acquisition in a half duplex mode.

In accordance with RS-232 interface specifications, the controller accepts a communications cable length. Once the desired set parameters are established, the PC may be disconnected and the 5R7-388 becomes a unique, stand-alone controller. All parameter settings are retained in nonvolatile memory. The 5R7-388’s additional features include 36-VDC output using split supply, a PC-configurable alarm circuit, and P, I, D, or On/Off control.

Contact Oven Industries for pricing.

Oven Industries, Inc.
www.ovenind.com

Data Acquisition Instrument

The DI-145 USB data acquisition instrument features four ±100-V analog channels and two dedicated digital inputs. The included DATAQ WinDaq data acquisition software (DAS) enables you to display and record data to a PC hard drive in real time. Once recorded, data can be played back, analyzed, or exported to an array of data acquisition and spreadsheet formats.

DATAQ also provides access to the DI-145 data protocol, which enables access to the DI-145 on any Windows, Linux, or MAC OS. In addition, .NET control is available to Windows users who wish to use a third-party programming language (e.g., Microsoft’s Visual Basic or National Instruments’s LabVIEW) to interface with the DI-145.

The four ±10-V fixed differential channels are protected from transient spikes up to ±150 V peak (±75 V, continuous). A 10-bit ADC provides 19.5-mV resolution across the full-scale measurement range. Digital inputs are protected up to ±30 VDC/peak AC. The digital inputs enable you to use a switch closure or TTL signal to remotely insert event marks or record data to disk.

The DI-145 measures 1.53” × 2.625” × 5.5” (3.89 cm × 6.67 cm × 13.97 cm) and weighs 3.6 oz. The data acquisition instrument costs $29 and includes a mini screwdriver, a USB cable, WinDaq/Lite DAS, access to the data protocol, and .NET control.

DATAQ Instruments, Inc.
www.dataq.com

Embedded Sensor Innovation at MIT

During his June 5 keynote address at they 2013 Sensors Expo in Chicago, Joseph Paradiso presented details about some of the innovative embedded sensor-related projects at the MIT Media Lab, where he is the  Director of the Responsive Environments Group. The projects he described ranged from innovative ubiquitous computing installations for monitoring building utilities to a small sensor network that transmits real-time data from a peat bog in rural Massachusetts. Below I detail a few of the projects Paradiso covered in his speech.

DoppleLab

Managed by the Responsive Enviroments group, the DoppelLab is a virtual environment that uses Unity 3D to present real-time data from numerous sensors in MIT Media Lab complex.

The MIT Responsive Environments Group’s DoppleLab

Paradiso explained that the system gathers real-time information and presents it via an interactive browser. Users can monitor room temperature, humidity data, RFID badge movement, and even someone’s Tweets has he moves throughout the complex.

Living Observatory

Paradiso demoed the Living Observatory project, which comprises numerous sensor nodes installed in a peat bog near Plymouth, MA. In addition to transmitting audio from the bog, the installation also logs data such as temperature, humidity, light, barometric pressure, and radio signal strength. The data logs are posted on the project site, where you can also listen to the audio transmission.

The Living Observatory (Source: http://tidmarsh.media.mit.edu/)

GesturesEverywhere

The GesturesEverywhere project provides a real-time data stream about human activity levels within the MIT Media Lab. It provides the following data and more:

  • Activity Level: you can see the Media Labs activity level over a seven-day period.
  • Presence Data: you can see the location of ID tags as people move in the building

The following video is a tracking demo posted on the project site.

The aforementioned projects are just a few of the many cutting-edge developments at the MIT Media Lab. Paradiso said the projects show how far ubiquitous computing technology has come. And they provide a glimpse into the future. For instance, these technologies lend themselves to a variety of building-, environment-, and comfort-related applications.

“In the early days of ubiquitous computing, it was all healthcare,” Paradiso said. “The next frontier is obviously energy.”

Embedded Wireless Made Simple

Last week at the 2013 Sensors Expo in Chicago, Anaren had interesting wireless embedded control systems on display. The message was straightforward: add an Anaren Integrated Radio (AIR) module to an embedded system and you’re ready to go wireless.

Bob Frankel demos embedded mobile control

Bob Frankel of Emmoco provided a embedded mobile control demonstration. By adding an AIR module to a light control system, he was able to use a tablet as a user interface.

The Anaren 2530 module in a light control system (Source: Anaren)

In a separate demonstration, Anaren electrical engineer Mihir Dani showed me how to achieve effective light control with an Anaren 2530 module and TI technology. The module is embedded within the light and compact remote enables him to manipulate variables such as light color and saturation.

Visit Anaren’s website for more information.

The Future of Data Acquisition Technology

Maurizio Di Paolo Emilio

Maurizio Di Paolo Emilio

By Maurizio Di Paolo Emilio

Data acquisition is a necessity, which is why data acquisition systems and software applications are essential tools in a variety of fields. For instance, research scientists rely on data acquisition tools for testing and measuring their laboratory-based projects. Therefore, as a data acquisition system designer, you must have an in-depth understanding of each part of the systems and programs you create.

I mainly design data acquisition software for physics-related experiments and industrial applications. Today’s complicated physics experiments require highly complex data acquisition systems and software that are capable of managing large amounts of information. Many of the systems require high-speed connections and digital recording. And they must be reconfigurable. Signals that are hard to characterize and analyze with a real-time display are evaluated in terms of high frequencies, large dynamic range, and gradual changes.

Data acquisition software is typically available in a text-based user interface (TUI) that comprises an ASCII configuration file and a graphic user interface (GUI), which are generally available with any web browser. Both interfaces enable data acquisition system management and customization, and you don’t need to recompile the sources. This means even inexperienced programmers can have full acquisition control.

Well-designed data acquisition and control software should be able to quickly recover from instrumentation failures and power outages without losing any data. Data acquisition software must provide a high-level language for algorithm design. Moreover, it requires data-archiving capability for verifying data integrity.

You have many data acquisition software options. An example is programmable software that uses a language such as C. Other software and data acquisition software packages enable you to design the custom instrumentation suited for specific applications (e.g., National Instruments’s LabVIEW and MathWorks’s MATLAB).

In addition to data acquisition software design, I’ve also been developing embedded data acquisition systems with open-source software to manage user-developed applications. The idea is to have credit-card-sized embedded data acquisition systems managing industrial systems using open-source software written in C. I’m using an ARM processor that will give me the ability to add small boards for specific applications (e.g., a board to manage data transmission via Wi-Fi or GSM).

A data acquisition system’s complexity tends to increase with the number of physical properties it must measure. Resolution and accuracy requirements also affect a system’s complexity. To eliminate cabling and provide for more modularity, you can combine data acquisition capabilities and signal conditioning in one device.

Recent developments in the field of fiber-optic communications have shown longer data acquisition transmission distances can cause errors. Electrical isolation is also an important topic. The goal is to eliminate ground loops (common problems with single-ended measurements) in terms of accuracy and protection from voltage spikes.

During the last year, some new technological developments have proven beneficial to the overall efficacy of data acquisition applications. For instance, advances in USB technology have made data acquisition and storage simpler and more efficient than ever (think “plug and play”). Advances in wireless technology have also made data transmission faster and more secure. This means improved data acquisition system and software technologies will also figure prominently in smartphone design and usage.

If you look to the future, consumer demand for mobile computing systems will only increase, and this will require tablet computers to feature improved data acquisition and storage capabilities. Having the ability to transmit, receive, and store larger amounts of data with tablets will become increasingly important to consumers as time goes on. There are three main things to consider when creating a data acquisition-related application for a tablet. Hardware connectivity: Tablets have few control options (e.g., Wi-Fi and Bluetooth). Program language support: Many tablets support Android apps created in Java. Device driver availability: Device drivers permit a high-level mode to easily and reliably execute a data acquisition board’s functionality. C and LabVIEW are not supported by Android or Apple’s iOS. USB, a common DAQ bus, is available in a set of tablets. In the other case, an adapter is required. In these instances, moving a possible data acquisition system to a tablet requires extra attention.

For all of the aforementioned reasons, I think field-programmable arrays (FPGAs) will figure prominently in the evolution of data acquisition system technology. The flexibility of FPGAs makes them ideal for custom data acquisition systems and embedded applications.

Microcontroller-Based Heating System Monitor

Checking a heating system’s consumption is simple enough.

Heating system monitor

Determining a heating system’s output can be much more difficult, unless you have this nifty design. This Atmel ATmega microcontroller-based project enables you to measure heat output as well as control a circulation pump.

Heating bills often present unpleasant surprises. Despite your best efforts to economise on heating, they list tidy sums for electricity or gas consumption. In this article we describe a relatively easy way to check these values and monitor your consumption almost continuously. All you need in order to determine how much heat your system delivers is four temperature sensors, a bit of wiring, and a microcontroller. There’s no need to delve into the electrical or hydraulic components of your system or modify any of them.

A bit of theory
As many readers probably remember from their physics lessons, it’s easy to calculate the amount of heat transferred to a medium such as water. It is given by the product of the temperature change ΔT, the volume V of the medium, and the specific heat capacity CV of the medium. The power P, which is amount of energy transferred per unit time, is:

P= ΔT × CV × V // Δt

With a fluid medium, the term V // Δt can be interpreted as a volumetric flow Vt. This value can be calculated directly from the flow velocity v of the medium and the inner diameter r of the pipe. In a central heating system, the temperature difference ΔT is simply the difference between the supply (S) and return (R) temperatures. This yields the formula:

P = (TS – TR) × CV × v × pr2

The temperatures can easily be measured with suitable sensors. Flow transducers are available for measuring the flow velocity, but installing a flow transducer always requires drilling a hole in a pipe or opening up the piping to insert a fitting.

Measuring principle
Here we used a different method to determine the flow velocity. We make use of the fact that the supply and return temperatures always vary by at least one to two degrees due to the operation of the control system. If pairs of temperature sensors separated by a few metres are mounted on the supply and return lines, the flow velocity can be determined from the time offset of the variations measured by the two sensors…

As the water flows through the pipe with a speed of only a few metres per second, the temperature at sensor position S2 rises somewhat later than the temperature at sensor position S, which is closer to the boiler.

An ATmega microcontroller constantly acquires temperature data from the two sensors. The time delay between the signals from a pair of sensors is determined by a correlation algorithm in the signal processing software, which shifts the signal waveforms from the two supply line sensors relative to each other until they virtually overlap.The temperature signals from the sensors on the return line are correlated in the same manner, and ideally the time offsets obtained for the supply and return lines should be the same.

To increase the sensitivity of the system, the return line sensor signals are applied to the inputs of a differential amplifier, and the resulting difference signal is amplified. This difference signal is also logged as a function of time. The area under the curve of the difference signal is a measure of the time offset of the temperature variations…

Hot water please
If the heating system is also used to supply hot water for domestic use, additional pipes are used for this purpose. For this reason, the PCB designed by the author includes inputs for additional temperature sensors. It also has a switched output for driving a relay that can control a circulation pump.

Under certain conditions, controlling the circulation pump can save you a lot of money and significantly reduce CO2 emissions. This is because some systems have constant hot water circulation so users can draw hot water from the tap immediately. This costs electricity to power the pump, and energy is also lost through the pipe walls. This can be remedied by the author’s circuit, which switches on the circulation pump for only a short time after the hot water tap is opened. This is detected by the temperature difference between the hot water and cold water supply lines…

Circuit description
The easiest way to understand the schematic diagram is to follow the signal path. It starts at the temperature sensors connected to the circuit board, which are NTC silicon devices.

Heating system monitor schematic

Their resistance varies by around 0.7–0.8% per degree K change in temperature. For example, the resistance of a KT110 sensor is approximately 1.7 kΩ at 5 °C and approximately 2.8 kΩ at 70 °C.

The sensor for supply temperature S forms a voltage divider with resistor R37. This is followed by a simple low-pass filter formed by R36 and C20, which filters out induced AC hum. U4a amplifies the sensor signal by a factor of approximately 8. The TL2264 used here is a rail-to-rail opamp, so the output voltage can assume almost any value within the supply voltage range. This increases the absolute measurement accuracy, since the full output signal amplitude is used. U4a naturally needs a reference voltage on its inverting input. This is provided by the combination of R20, R26 and R27. U5b acts as an impedance converter to minimise the load on the voltage divider…

Thermal power

PC connection
The circuit does not have its own display unit, but instead delivers its readings to a PC via an RS485 bus. Its functions can also be controlled from the PC. IC U8 looks after signal level conversion between the TTL transmit and receive lines of the ATmega microcontroller’s integrated UART and the differential RS485 bus. As the bus protocol allows several connected (peer) devices to transmit data on the bus, transmit mode must be selected actively via pin 3. Jumper JP3 must be fitted if the circuit is connected to the end of the RS485 bus. This causes the bus to be terminated in 120 Ω, which matches the characteristic impedance of a twisted-pair line…

[Via Elektor-Projects.com]