Circuit Cellar’s sister website Linuxgizmos,com has posted its 2019 New Year’s edition catalog of hacker-friendly, open-spec SBCs that run Linux or Android. The catalog provides recently updated descriptions, specs, pricing, and links to details for all 122 SBCs.
Segger Microcontroller has introduced emPower-USB-Host, a compact low-cost development board. With two USB host ports, many applications using USB peripherals can be realized with little effort. Precompiled applications for barcode and smartcard readers, as well as POS displays, LTE sticks and USB to LAN adapters are available for download, including complete projects for Embedded Studio with source code of these applications. The applications are using Segger’s emUSB-Host software API, which makes accessing the different types of USB devices easy.
emPower-USB-Host uses the emLoad bootloader, pre-loaded into the flash of the MCU, to easily change applications in seconds using a USB flash drive. Development of custom applications is also supported. The board has a debug connector, providing full access to the NXP LPC54605J512 MCU with its Cortex-M4 core. Schematics and PCB layout of the board are available under a Creative Commons license. This way, the hardware can be used as a blueprint for custom devices using two USB host ports.
Segger Microcontroller | www.segger.com
Doing a signature analysis of a signal used to require an oscilloscope to display your results. In this article, Brian details how to build a free-standing tester using mostly just the internal peripherals of an NXP Arm microcontroller. He describes how the tester operates and how he implemented it.
By Brian Millier
When I was a teenager starting out in electronics, I longed to have as much test equipment as possible. At that stage in life, I couldn’t afford much beyond a multimeter. I remember seeing plans for a component tester in an electronics magazine. There weren’t many hobby electronics magazines back in the ‘60s, so it was probably Popular Electronics. This tester would provide a “signature” of most passive/active components by placing a small AC voltage across the component and measuring the resulting current. My memory of the circuit is hazy after all these years, but it was trivial: a 6.3 V filament transformer, a current sensing resistor and a few other passive components. However, the catch was that it required an oscilloscope to display the resulting voltage vs. current plot—in other words, the component’s signature. By the time I bought an oscilloscope about 10 years later, I had completely forgotten about this testing concept.
Today, test instruments are available that include a dedicated graphics display, instead of relying on an oscilloscope for display purposes. Having worked with Arm microcontrollers over the last few years,
I realized that I could implement such a free-standing tester using, in large part, just the internal MCU peripherals.
In this article I’ll describe how the tester operates, and how I implemented it using a Teensy 3.5 development module (containing an NXP MK64FX512VMD12 MCU) and featuring a FT800-based intelligent 4.3″ TFT touch-screen display.
Basic Theory of Operation
To obtain a signature of a given component, you need to place a variable voltage across it and measure the resulting current through it, at each voltage level. In many cases, the component’s normal operating mode will include both positive and negative voltages across it, so the tester must provide an AC voltage source. For most testing purposes you would use a sine wave voltage source because most AC calculations are done using sine waves. The value of this AC voltage source must be adjustable. I decided on six ranges between 0.5 V peak-peak and 20 V peak-peak. For measuring the voltage across the component, I used an instrumentation amplifier with three hardware gain ranges—plus three additional ranges based upon scaling in software.
To monitor current, it’s easiest to measure the voltage across a small value resistor placed in the ground return path, and then convert that to current using Ohm’s Law. Here too you need a range of current measurements. I chose to provide three hardware ranges—plus four additional ranges based on software scaling—between 1 mA and 100 mA.
You can’t just place an AC voltage of any given value across a component, and hope that the component will be able to handle that current without damage. You must place a resistor in series with the component to limit the current flow. That resistor may need to vary in value over several decades, depending on the component being tested. In my tester, I provide a switchable resistor bank with values covering a 1,000:1 range in decade steps.
Figure 1 is a block diagram of the basic tester circuitry. The user interface, touch-screen display and SD card data storage are not shown here. The MK64FX512VMD12 MCU’s 12-bit DAC A provides a sine wave signal that varies between 0 and 1.2 V over the full AC cycle. The programmable attenuator is an SPI pot device with 12-bit resolution. C1 is a decoupling capacitor, which shifts the (attenuated) unipolar DAC A output signal into a bipolar AC signal. This AC signal is amplified by a factor of 21 by an LM675 power amplifier IC. DAC B, along with some passive components, provide a software-adjustable offset voltage adjustment. The LM675 amplifier is needed to provide enough drive current to handle the higher current ranges—up to 100 mA.
Both the voltage and current are monitored using Texas Instruments (TI)instrumentation amplifier ICs. These contain input protection circuitry good to ±40 V. The various gains needed for both amplifiers are set by 1% resistors, which are switched by miniature reed relays. The instrumentation amplifier output voltages, representing voltage and current through the component under test, are fed to the two 16-bit ADCs present in the NXP MK64FX512VMD12 Arm MCU. The sine wave signal generated by the MCU can be set for frequencies of 20, 50 ,60, 100, 200 or 400 Hz.
The basic premise of signature analysis is that you obtain a signature of a component that is of questionable condition, and then compare it with a known-good component of the same value. Alternately, you can do the same comparison on a specific circuit node on two identical circuit boards/assemblies.. …
Read the full article in the August 337 issue of Circuit Cellar
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Circuit Cellar’s sister website LinuxGizmos.com has completed its 2018 hacker board survey, which ran on SurveyMonkey in partnership with Linux.com. Survey participants chose the new Raspberry Pi 3 Model B+, as the favorite board from among 116 community-backed SBCs that run Linux or Android and sell for under $200.
All 116 SBCs are summarized in LinuxGizmos’ recently updated hacker board catalog and feature comparison spreadsheet.
UPDATE: We’ve extended our 2018 reader survey on open-spec Linux/Android hacker boards through this Friday, June 22. Vote now!
Circuit Cellar’s sister website LinuxGizmos.com has launched its fourth annual reader survey of open-spec, Linux- or Android-ready single board computers priced under $200. In coordination with Linux.com, LinuxGizmos has identified 116 SBCs that fit its requirements, up from 98 boards in its June 2017 survey.
Vote for your favorites from LG’s freshly updated catalog of 116 sub-$200, hacker-friendly SBCs that run Linux or Android, and you could win one of 15 prizes.
Check out LinuxGizmos’ freshly updated summaries of 116 SBCs, as well as its spreadsheet that compares key features of all the boards.
Explore this great collection of Linux SBC information. To find out how to participate in the survey–and be entered to win a free board–click here:
Renesas Electronics has announced three new Target Boards for the RX65N, RX130 and RX231 Microcontroller (MCU) Groups, each designed to help engineers jump start their home appliance, building and industrial automation designs. Priced below $30, the Target Boards lower the price threshold for engagement, allowing more system developers to make use of Renesas’ broad-based 32-bit RX MCU family.
The RX Target Boards provide an inexpensive entry point for embedded designers to evaluate, prototype and develop their products. Each board kit features an on-chip debugger tool that enables application design without requiring further tool investments. Through-hole pin headers provide access to all MCU signals pins, making it easy for users to interconnect to standard breadboards for fast prototyping.
The RX Target Board evaluation concept reuses the same PCB for all MCU variations. Since each member of the Renesas RX MCU Family has a common pin assignment, users experience a smooth transition between different RX Groups and RX Series using the same package version. In the case of the RX Target Boards, the widely used 100-pin LQFP package is on board.
The RX Target Boards offer everything designers need to start board and demo development, including a board circuit diagram and bill of materials, demo source code, user manual, and application notes. Additional Target Board variations will be released soon that will provide full coverage of the entire RX Family, from the low-power RX100 Series to the high-performance RX700 Series.
The RX65N MCU Group combines an enhanced RX CPU core architecture and 120 MHz operation to achieve processing performance of 4.34 CoreMark/MHz. The MCUs include an integrated Trusted Secure IP, enhanced, trusted flash functionality, and a human-machine interface (HMI) for industrial and network control systems operating at the edge of the Industrial Internet of Things (IIoT). The RX65N MCUs also include an embedded TFT controller and integrated 2D graphic accelerator with advanced features ideal for TFT displays designed into IIoT edge devices or system control applications. In addition, the RX65N MCUs include embedded communication-processing peripherals such as Ethernet, USB, CAN, SD host/slave interface and quad SPI.
The RX130 MCU Group provides 32 MHz operation with flash memory sizes up to 512 KB, and package sizes up to 100-pins to provide higher performance and compatibility with the RX231/RX230 Group of touch MCUs. The ultra-low power, low-cost RX130 Group adds higher responsiveness and functionality for touch-based applications requiring 3V or 5V system control and low power consumption. Featuring a new capacitive touch IP with improved sensitivity and robustness, and a comprehensive device evaluation environment, the new 32-bit RX130 MCUs are an ideal fit for devices designed with challenging, non-traditional touch materials, or required to operate in wet or dirty environments, such as a kitchen, bath or factory floor.
The RX Target Boards are available now through Renesas Electronics’ worldwide distributors with a recommended resale price below $30.
Renesas Electronics | www.renesas.com
STMicroelectronics has extended its STM32 software ecosystem with a Sigfox package that simplifies development and gives extra flexibility to connect Internet-of-Things (IoT) devices to long-range, low-power wireless networks. The new X-CUBE-SFOX package is ready to use with ST’s B-L072Z-LRWAN1 Discovery Kit, which is already LoRa enabled through I-CUBE-LRWAN embedded software. Developers can now work with either of these established Low-Power Wide Area Network (LPWAN) technologies on the same hardware, and create products that can use the two protocols individually or alternatively.
With over 700 STM32 variants, from ultra-low-power to high-performance lines, developers can leverage unrivaled flexibility to optimize the performance and features of IoT devices that take advantage of Sigfox services including basic connectivity, radio recognition, and GPS-free location. The software’s low memory footprint and efficient CPU utilization minimize demand for system resources, helping to lower bill-of-materials (BOM) costs and power consumption.
The X-CUBE-SFOX software can be downloaded free of charge from www.st.com/x-cube-sfox. The B-L072Z-LRWAN1 Discovery Kit is available now, priced $46.50.
STMicroelectronics | www.st.com
Imagination recently launched the MIPS Creator CI20 development board, which is targeted at hobbyists, makers and schools working on open source projects. The system supports Linux (currently running Debian 7, but other images are also supported) and by the end of September Android 4.4 KitKat.
Its main hardware features include:
- Ingenic JZ4780, dual 1.2-GHz MIPS32 processor, SGX540 GPU, 32k I&D L1 cache, 512-KB L2 cache
- IEEE754 Floating Point Unit
- 8-GB Flash, 1-GB DDR3 memory
- Video playback up to 1080p
- AC97 audio, via 4-pin input/output jack and HDMI connector
- Camera interface –ITU645 controller
- Connectivity – 10/100 Ethernet, 802.11 b/g/n, Bluetooth 4.0
- HDMI output up to 2K resolution
- 2 x USB – host and OTG
- 14-pin ETAG connector
- 2 x UART, GPIO, SPI, I2C, ADC, expansion headers
- Power supply
For a chance of receiving a free board, you just need to register and describe the project you want to build. If you are lucky and the company likes the sound of your proposal, you will be one of 1000 entrants to receive a free Creator CI20 development board. For more information go to the Imagination web site and fill out a request form.
The TT Series remote-control transceiver is designed for bidirectional, long-range, remote-control applications. The module includes an optimized frequency-hopping spread spectrum (FHSS) RF transceiver and an integrated remote-control transcoder.
The FHSS is capable of reaching more than 2 miles in typical line-of-sight environments with 0-dB gain antennas. An amplified version increases the output power from 12.5 to 23.5 dBm, boosting the range to more than 8 miles in line-of-sight environments with 0-dB antennas.
The TT Series transceiver features best-in-class receive sensitivity (up to −111 dBm) and low power consumption (only 19.2 mA in receive mode and 36 mA in transmit mode at 12.5 dBm). The initial version operates in the 902-to-928-Hz frequency band for North and South America.
The transceiver is housed in a compact reflow-compatible surface-mount technology (SMT) package. It doesn’t require any external RF components except an antenna, which simplifies integration and reduces assembly costs.
Programming is not required for basic operation. The transceiver’s primary settings are hardware-selectable, which eliminates the need for an external microcontroller or other digital interface. Eight status lines can be set up in any combination of inputs and outputs to transfer button or contact states. A selectable acknowledgement indicates that the transmission was successfully received. For advanced features, a UART interface provides optional software configuration.
A simple pairing operation configures two modules to operate together. A single button press on each side causes the modules to automatically swap their 32-bit addresses and store them in nonvolatile memory. It can be configured to automatically send an acknowledgement to the transmitting unit either after receiving a command or with external circuitry when an action has taken place. An optional external processor can send two data bytes with the acknowledgement.
The TT Series transceiver module is available as part of Linx Technologies’s master development system that comes with two development boards for benchmarking and prototyping. Each board is populated with a transceiver, two remote-control development boards, and programming boards. The system also includes antennas, a daughterboard with a USB interface, demonstration software, extra modules, and connectors.
Contact Linx Technologies for pricing.
As a freelance engineer, Raul Alvarez spends a lot of time on the go. He says the last four or five years he has been traveling due to work and family reasons, therefore he never stays in one place long enough to set up a proper workspace. “Whenever I need to move again, I just pack whatever I can: boards, modules, components, cables, and so forth, and then I’m good to go,” he explains.
He continued by saying:
In my case, there’s not much of a workspace to show because my workspace is whichever desk I have at hand in a given location. My tools are all the tools that I can fit into my traveling backpack, along with my software tools that are installed in my laptop.
Because in my personal projects I mostly work with microcontroller boards, modular components, and firmware, until now I think it didn’t bother me not having more fancy (and useful) tools such as a bench oscilloscope, a logic analyzer, or a spectrum analyzer. I just try to work with whatever I have at hand because, well, I don’t have much choice.
Given my circumstances, probably the most useful tools I have for debugging embedded hardware and firmware are a good-old UART port, a multimeter, and a bunch of LEDs. For the UART interface I use a Future Technology Devices International FT232-based UART-to-USB interface board and Tera Term serial terminal software.
Currently, I’m working mostly with Microchip Technology PIC and ARM microcontrollers. So for my PIC projects my tiny Microchip Technology PICkit 3 Programmer/Debugger usually saves the day.
Regarding ARM, I generally use some of the new low-cost ARM development boards that include programming/debugging interfaces. I carry an LPC1769 LPCXpresso board, an mbed board, three STMicroelectronics Discovery boards (Cortex-M0, Cortex-M3, and Cortex-M4), my STMicroelectronics STM32 Primer2, three Texas Instruments LaunchPads (the MSP430, the Piccolo, and the Stellaris), and the following Linux boards: two BeagleBoard.org BeagleBones (the gray one and a BeagleBone Black), a Cubieboard, an Odroid-X2, and a Raspberry Pi Model B.
Additionally, I always carry an Arduino UNO, a Digilent chipKIT Max 32 Arduino-compatible board (which I mostly use with MPLAB X IDE and “regular” C language), and a self-made Parallax Propeller microcontroller board. I also have a Wi-Fi 3G TP-LINK TL-WR703N mini router flashed with OpenWRT that enables me to experiment with Wi-Fi and Ethernet and to tinker with their embedded Linux environment. It also provides me Internet access with the use of a 3G modem.
In three or four small boxes I carry a lot of sensors, modules, ICs, resistors, capacitors, crystals, jumper cables, breadboard strips, and some DC-DC converter/regulator boards for supplying power to my circuits. I also carry a small video camera for shooting my video tutorials, which I publish from time to time at my website (www.raulalvarez.net). I have installed in my laptop TechSmith’s Camtasia for screen capture and Sony Vegas for editing the final video and audio.
Some IDEs that I have currently installed in my laptop are: LPCXpresso, Texas Instruments’s Code Composer Studio, IAR EW for Renesas RL78 and 8051, Ride7, Keil uVision for ARM, MPLAB X, and the Arduino IDE, among others. For PC coding I have installed Eclipse, MS Visual Studio, GNAT Programming Studio (I like to tinker with Ada from time to time), QT Creator, Python IDLE, MATLAB, and Octave. For schematics and PCB design I mostly use CadSoft’s EAGLE, ExpressPCB, DesignSpark PCB, and sometimes KiCad.
Traveling with my portable rig isn’t particularly pleasant for me. I always get delayed at security and customs checkpoints in airports. I get questioned a lot especially about my circuit boards and prototypes and I almost always have to buy a new set of screwdrivers after arriving at my destination. Luckily for me, my nomad lifestyle is about to come to an end soon and finally I will be able to settle down in my hometown in Cochabamba, Bolivia. The first two things I’m planning to do are to buy a really big workbench and a decent digital oscilloscope.
Alvarez’s article “The Home Energy Gateway: Remotely Control and Monitor Household Devices” appeared in Circuit Cellar’s February issue. For more information about Alvarez, visit his website or follow him on Twitter @RaulAlvarezT.