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

August Schematic Challenge (Sponsor: Technologic Sysetms)

Can you spot the error in this month’s schematic challenge (sponsored by Technologic Systems)? This your chance to put your technical skills to test. Find the error in the schematic for a shot to win prizes, such as a TS-7250-V2 High-Performance Embedded Computer or a Circuit Cellar Digital Subscription.

Click to enlarge. Find the error and submit your answer via the online submission form.

Click to enlarge. Find the error and submit your answer via the online submission form.

Take the challenge now!

Tool for Selecting Coils for Wireless Power Transfer

Wurth Elektronik now offers developers with a tool—Mix and Match—to help select the right transmitter and receiver coils. Mix and Match is a new tool in the RED EXPERT Toolbox. Also like the other tools in RED EXPERT, Mix and Match shows online accessible product specifications. While some combinations of transmitter and receiver coils work well, some combinations aren’t good matches. Mix and Match helps you find suitable coils for your application.Wurth MixMatch

The free Mix and Match online tool will be expanded as time goes on. In Q4 2016, Wurth is slated to publish data on the resonant circuits of the coil combinations tested.

Source: Wurth Elektronik

Low-Power BLE Sensor Node for IoT Applications

Microchip Technology recently released a demonstration platform for the lowest-power Bluetooth Low Energy (BLE) sensor node. The platform features an ultra-low-power BTLC1000-certified module, a SMART SAM L21 Cortex-M0+ MCU, Bosch sensor technology, and a complete software solution. The BLE demonstration platform includes source code, hardware design files, a user guide, and Android application source code.Microchip BLE Demo Platform

Features, benefits, and specs:

  • An integrated BTLC1000-MR110CA BLE module, delivering at least 30% more power savings compared to existing solutions.
  • An ultra-tiny 2.2 mm × 2.1 mm Wafer Level Chipscale Package (WLCP).
  • A SAM L21 that achieves a ULPBench score of 185, with power consumption down to 35 µA/MHz in active mode and 200 nA in sleep mode.
  • Bosch six-axis motion (BHI160) and environment (BME280) sensors that can be used for a wide variety of sensing applications.

The Ultra-Low-Power Connected Demonstrator Platform costs $39.

Source: Microchip Technology

Qi-Certified, 15-W Wireless Power Transmitter

Texas Instruments now offers the industry’s first WPC v1.2 Qi-certified, 15-W wireless power transmitter. Intended to deliver high-power wireless charging to industrial systems (e.g., hand-held medical devices), the bq501210 enables 84% system efficiency with significantly less thermal dissipation.TI bq501210

The bq501210’s features, benefits, and specs:

  • Fixed-frequency operation enables 15-W efficiency and reduces electromagnetic interference (EMI).
  • Fast-charging capability enables the transfer of up to 10 W to compatible receivers, including currently available fast-charging devices.
  • The High-Voltage Dedicated Charging Port (HVDCP) protocol negotiates with capable AC/DC wall adapters to adjust the input voltage.

The bq501210 transmitter is shipping in volume production. It comes in a 9 mm × 9 mm VQFN package and costs $3.75 in 1,000-unit quantities. An evaluation module (bq501210EVM-756) is available for $149.

Source: Texas Instruments

The Future of IoT Security: One Size Doesn’t Fit All

Security is one of the hot topics today in the Internet of Things (IoT). There have been well-publicized security breaches of consumer devices that include hijacked video from wireless baby monitors being posted on the Internet and home automation systems that reveal whether a home is occupied or not. A number of systems have been breached just to demonstrate their vulnerabilities. Less well publicized are security breaches of industrial equipment with much more severe consequences. These are rarely made public for obvious reasons.

At first glance, it would seem that the existing security mechanism for the Internet and corporate networks would be an easy solution for IoT security. There are several problems with this. First, IoT applications only require security that is “good enough” for the specific application. Just like you don’t need razor wire and guard towers to keep your dog in the yard and don’t want to rely on a four foot yard fence to keep the prisoners in a maximum security prison, the level of security for an IoT product needs to be based on the needs of the application (often basic privacy rather than real security).

Consider data encryption for network transfers as an example of why existing security mechanisms generally do not work well for the IoT. Encryption standards typically target applications that require extremely high levels of security such as financial transactions and military or national security communications. These encryption standards are severe overkill for most IoT applications and present significant problems for small, battery-powered IoT devices. An encryption algorithm may require upwards of 4 KB of code space, which is as much or more than many otherwise suitable microcontrollers might have. Many encryption standards rely on multiple rounds of encryption. The time it takes to perform the encryption could be several times longer on a small micro than the time it takes the micro to perform its main tasks. Most common encryption standards rely on 16- to 32-byte keys to help ensure data security. For many IoT devices, these key lengths could increase the length of their network messages by a factor of 4× to 8× or more. The execution time and added network traffic can quickly chew-up precious battery capacity, increasing the size and cost of a product. The extremely high level of security provided by these encryption algorithms is what drives the large code size, long execution times, and high message overhead that makes them inappropriate for most IoT applications. Hardware encryption addresses the code size and execution time issues but still suffers from high message overhead.

 

The other major problem with using existing security mechanisms is IoT developers typically don’t have network security experience. There is a certain mindset and expertise required to develop IoT products and a completely different mindset and expertise required to be a security expert. The time required to develop these security mechanisms in-house could take several times longer than the basic product development. Several companies have recognized this problem and have recently introduced security framework products to be incorporated into IoT devices. True end-to-end security requires much more than just passwords and data encryption, and these framework products address other needs like key management and protection against common network attacks. These security frameworks may well be the future of IoT security, but to be widely adopted, they have to be right-sized for IoT devices.

When selecting the wireless technology to use in an IoT product, things like distance, bandwidth, cost, and physical size have to be considered. Words and phrases like “streamlined” and “light weight” need to be kept in mind when assessing security solutions for IoT products. A feature-rich security framework product might be appealing, but many IoT devices provide simple functions and don’t need a plethora of features. They also can’t afford the memory space and execution time overhead (and power consumption) imposed by these unneeded features. Whether future IoT products are based on a security framework or in-house developed security, there will not be a one-size-fits-all solution. Security for successful IoT products will be right-sized for the hardware resources available and the needs of the application.

Mike Lease is a hardware/firmware engineer with more than 30 years of product development experience, mostly in embedded products. He developed a number of battery-powered, wirelessly connected devices before “IoT” became a common buzzword, and several more since then. Mike enjoys taking on tough challenges and has recently developed a fascination with generating random numbers. In 2013 he founded CMicrotek (www.cmicrotek.com) to develop a family of ultra-low current measurement products primarily for developers of battery-powered products. Mike recently launched LSE Technologies, a provider of lightweight stream encryption software for M2M and IoT applications.

Hi-Fi Audio Engineering Workspace

Jan  Didden is a talented audio engineer and author with a well-stocked lab in Turnhout, Belgium. He recently gave us a tour of space and talked about his current audio design projects.

This is an excellent place to work. It is a converted army barrack so, being an old army man myself, I feel comfortable here. Above me there is the Tax department and one floor below there is a medical department. I am safe from all sides. I have two rooms, one for studying and listening and one for all the projects and equipment.L1070786

One  of his current  projects is an amplifier for electrostatic speakers.

An electrostatic speaker works with a very thin foil to make the air move. To get that thin foil moving you need to apply a high voltage. That is normally done with transformers that transform the low voltage audio signal from the amplifier to a higher value. But a transformer is not a linear component and can introduce all sorts of distortion to the signal. The solution is to make an amplifier that produces a high voltage output directly, but there are not many transistors capable of providing these high voltages.

He also described a project he might showcase on Kickstarter in the near future.

My other project is very interesting for people who are using computers for measurement and testing audio. They all use a sound card (internal or external) but these cards have a limitation on the input voltage. That is typically around the 1 V. The project I am working on is an ‘auto ranger.’ It automatically scales the signal to measure to the right input voltage for the sound card. I think a lot of people will like that and I hope to make this product available, perhaps by making it a Kickstarter project.

Renesas Electronics Europe and SEGGER Accelerate RX Ecosystem Expansion

Renesas Electronics Europe and SEGGER recently announced their collaboration to facilitate the expansion of Renesas’s RX Family of 32-bit microcontroller ecosystem through the adoption of SEGGER’s newly-released SystemView software. SystemView supports streaming over J-Link, as well as real-time analysis and visualization, in relation to any Renesas RX-based embedded design.Segger RS

SystemView gives you insight into the behavior of a program. It offers cycle accurate tracing of interrupts and task start/stop in addition to task activation and API calls when an RTOS is used. It visualizes and analyzes CPU load by task, interrupts, and software timers. Using SEGGER’s J-Link debug probe with SystemView enables real-time analysis, which gives you an in-depth understanding of the application’s run-time behavior.

SystemView uses SEGGER’s Real-Time Transfer (RTT) technology to ensure real-time delivery of data and minimal intrusiveness on the system. RTT enables up to 2 MB per second data transfer for continuous acquisition of real-time data, requiring no hardware other than a J-Link and the standard debug interface. SystemView records the data retrieved from the target and visualizes the results in different ways. You can save data recordings for later documentation and analysis.

SystemView works seamlessly with SEGGER’s RTOS embOS, which includes all the necessary recording capabilities. SystemView doesn’t require any OS involvement.

Source: SEGGER

STMicroelectronics Certifies Cryptographic Library for STM32 MCUs

STMicroelectronics has successfully certified its cryptographic library for STM32 microcontrollers as per the US Cryptographic Algorithm Validation Program (CAVP). An extension to the STM32Cube software package, the X-CUBE-CRYPTOLIB library is well suited for secure STM32-based applications, such as IoT devices, point-of-sale terminals, and smart meters.

The STM32 cryptographic library includes all the major security algorithms for encryption, hashing, message authentication, and digital signing. This enables you to meet application requirements for any combination of data integrity, confidentiality, identification/authentication, and non-repudiation. The library includes firmware and hardware-acceleration functions for some STM32 families.

There are examples for each algorithm and template projects for popular development tools such as Keil MDK-ARM, IAR Embedded Workbench EWARM, and GCC-based IDEs (e.g., Ac6 SW4STM32 and Atollic TrueSTUDIO).

The approved algorithms are AES (validation number 3971), RSA (2036), ECDSA (874), SHS (3275), DRBG (1165) and HMAC (2589). Full details are available online at the NIST CSRC Algorithm Validation Lists webpage. X-CUBE-CRYPTOLIB contains many further algorithms, including DES, TripleDES, MD5, ECC with key generation, ChaCha20, Poly1305, Curve25519 and others.

The X-CUBE-CRYPTOLIB for STM32 is available free of charge under the terms of STMicro’s Software License Agreement (SLA0048).

Source: STMicroelectronics

FTDI Arduino-Compatible Touch-Enabled Display Shield Now Shipping

FTDI Chip recently announced the widespread availability of its originally crowdfunded CleO product (and accompanying accessories). FTDI Chip also offers access to software tools, step-by-step tutorials, and projects. FTDI CleOCleO is a simple to program, intelligent TFT display solution that for building human machine interfaces (HMIs) with higher performance than typical Arduino display shields. The initial CleO includes an HVGA resolution, 3.5″ TFT display featuring a resistive touchscreen. An FTDI Chip FT810 high-resolution embedded video engine (EVE) graphic controller executes the HMI operation. An FTDI FT903 microcontroller handles all the additional processing tasks. The advanced display shield provides high-quality graphical animation, even at 60-fps frame rates. In addition, its antialiased graphics capabilities render images in finer detail.

When CleO is combined with FTDI Chip’s NerO—which is an energy-efficient Arduino design capable of operating up to 1 W—it offers a far more powerful solution than a normal Arduino UNO/display shield package.

CleO has an array of useful accessories:

  • AT 57.15 mm × 54.35 mm, the CleO-RIO module provides a mechanism for stacking the CleO shield and an Arduino board together.
  • The CleO-Speaker module (63 mm × 63 mm × 23.8 mm) facilitates the playback music/tones for HMIs where audio functionality has been incorporated. There is also an audio line for input of audio from external sources.
  • The CleO-Camera module has an OV5640 0.25″ 5-megapixel CMOS image sensor plus flash LEDs and a 24-pin 0.5-mm pitch FFC cable.
  • A 9-V power adaptor provides the NerO/CleO solution with up to 1 A of current.

The CleO costs $69. Refer to FTDI’s new forum, www.CleOstuff.com, for design tips, application ideas, and more.

Source: FTDI Chip

IEC Adopts USB Type-C, USB Power Delivery, & USB 3.1 Specs

The International Electrotechnical Commission (IEC) and USB Implementers Forum (USB-IF) recently announced that IEC has formally adopted the latest USB-IF specifications for high-speed data delivery and enhanced usages for device charging. In particular, the USB Type-C Cable and Connector, USB Power Delivery and USB 3.1 (SuperSpeed USB 10 Gbps) specifications. These specifications define a truly single-cable solution for audio/video, data, and power delivery.

The standards are expected to advance global action on reducing e-waste and improving the reusability of power supplies with a range of electronic devices. The IEC approach for ongoing standardization work in this space is driven by the ultimate goals of increasing external power supply re-usability, supporting consumer convenience, maintaining product reliability and safety, and providing for future technology innovations. In addition, widespread adoption of the resulting International Standards will help to reduce the encroachment of poorly designed or manufactured aftermarket substitutes which may affect the operation of electronic devices in compliance with regulatory requirements.USB

The IEC specification numbers :

  • IEC 62680-1-3 (USB Type-C)
  • IEC 62680-1-2 (USB PD)
  • IEC 62680-3-1 (USB 3.1)

The USB Type-C specification defines the physical USB Type-C cable and connector form factor to facilitate thinner and sleeker product designs, enhance usability and provide a growth path for performance enhancements for future versions of USB.

USB Power Delivery was developed to provide flexible, bi-directional power capabilities by enabling faster charging and increased power levels up to 100W. The USB Power Delivery specification defines standardized features that support the global adoption of interoperable power supplies, helping to reduce electronic waste and increase re-usability of adapters and chargers for consumer electronics.

USB 3.1 enables speeds up to 10 Gbps, supporting audio/video for USB hosts, hubs, and devices. Combined with USB Type-C, USB 3.1 and USB Power Delivery define a truly single-cable solution for audio/video, data and power delivery, building on the existing global ecosystem of USB/IEC 62680 series of International Standards compliant devices.

The International Electrotechnical Commission (IEC) brings together 166 countries, representing 98% of the world population and 96% of world energy generation, and close to 15,000 experts who cooperate on the global, neutral and independent IEC platform to ensure that products work everywhere safely with each other. The IEC is the world’s leading organization that prepares and publishes globally relevant International Standards for the whole energy chain, including all electrical, electronic and related technologies, devices and systems. The IEC also supports all forms of conformity assessment and administers four Conformity Assessment Systems that certify that components, equipment and systems used in homes, offices, healthcare facilities, public spaces, transportation, manufacturing, explosive environments and energy generation conform to them.

IEC work covers a vast range of technologies: power generation (including all renewable energy sources), transmission, distribution, Smart Grid & Smart Cities, batteries, home appliances, office and medical equipment, all public and private transportation, semiconductors, fiber optics, nanotechnology, multimedia, information technology, and more. It also addresses safety, EMC, performance, and the environment.

Source: International Electromechanical Commission

Debugging Embedded Systems with Minimal Resources

Debugging an embedded system can be difficult when you’re dealing with either a simple system with few pins or a complex system with nearly every pin in use. Stuart Ball provides some tips to make debugging such systems a little easier.

Debugging a microcontroller system can be difficult. Things don’t work right and it often isn’t even clear why. Was something initialized wrong? Is it a timing issue? Is there conflicting use of shared resources?

Debugging is more complicated when there are limited resources. If all the processor pins are used, what do you connect to? How do you get debug information out of the firmware so you can see what is going on?

This article isn’t about debugging when you have Ethernet, USB, and Bluetooth interfaces available, or when you have a full-speed emulator. This is about debugging when there aren’t many resources available—simple systems with few pins, or more complex systems with nearly every pin already used for something.

This is the schematic for a serial port RS-232 driver. It's a standardized circuit that plugs into a header on the board to be debugged.

Figure 1: This is the schematic for a serial port RS-232 driver. It’s a standardized circuit that plugs into a header on the board to be debugged.

Postmortem vs. Real-Time Debugging

There are two general ways of debugging an embedded system. One is postmortem, looking at the state of the system after it has failed or after it has stopped at a breakpoint. The other is real-time, debugging while the system is running. Each has its own place and its own set of challenges.

Generally, the two methods use different debug techniques. A postmortem debug happens when the motor is stalled, the software can’t recover, and you have no idea why it happened. You want to know the system’s state and how it got there. Setting breakpoints is a method used in postmortem debugging; you stop the system and look at the static state after a particular point in the code is reached.

Real-time or active debugging is more appropriate for looking at timing issues, missed interrupts, cumulative latency issues, and cases where the system just does occasionally does something strange but doesn’t actually stop. Real-time debug can tell you how the system got into the state that you are trying to analyze using postmortem methods. If you can capture enough information while the system is running, you have a chance to turn a real-time problem into a simpler static post-mortem analysis.

This article appears in Circuit Cellar 312, July 2016. Download the complete article.

Universal Debug Solution

An asynchronous serial port may be the most common debug tool used in the embedded world. Most microcontrollers have at least one serial port built in. The serial port has limitations. Its speed is limited and it requires level translation to connect it to the RS-232 voltage levels of a PC.

In many cases, you might not want to put the RS-232 driver on your board. You don’t want to use the space required by either the IC or the RS-232 connector, especially for something that is only used while debugging. One way I’ve solved this problem is shown in Figure 1, which depicts just a Maxim Integrated (or Texas Instruments) MAX3232 RS-232 driver IC connected to a DE9 connector. The other side connects to a four-pin header. This is connected via a cable to the embedded system to be tested. This allows the embedded system to have just the four-pin connector wired to the microcontroller serial port pins, power, and ground.

You plug in the external circuit when you need to debug and unplug it when you are done. There is nothing special about this circuit, it is exactly the same as you might put on your microcontroller board. Except you don’t need the space on your board for this. The circuit takes power from the microcontroller board via pins 1 and 4 of the four-pin Molex connector. The connector indicated is polarized so you can’t plug it in backward. I’ve standardized on this in my embedded systems at least where the serial port is used for debug or download.

Although I used a connector with 0.1” centers on the interface board, there is nothing to prevent you from using a 2 mm or 0.05” connector, or even a row of pads at the edge of the board being debugged. You just have to make a cable that has the Molex connector at one end and whatever you need to match your embedded board at the other end. You can keep the driver board in your toolbox, put the connector on your embedded system boards, and you have it when you need it.

You can house the board into a plastic project box. In one case, I built one on a narrow piece of perforated project board, and covered the entire thing in heat shrink tubing. It has the right-angle Molex connector on one end, and a short cable with the RS-232 connector on the other end. I keep that one in my desk drawer at work.

Read the entire article (PDF)

Industry’s First Open-Source SoC Platforms

SiFive recently introduced the Freedom family of system on a chip (SoC) platforms that are built around the open-source RISC-V instruction set architecture, which was developed by the company’s founders at the University of California, Berkeley.

Features and specs:

  • Freedom U500 Series: The Freedom Unleashed (U) family features a fully Linux-capable embedded application processor featuring the world’s most advanced, multi-core RISC-V CPUs, running at a speed of 1.6 GHz or higher with support for accelerators and cache coherency. Designed in TSMC 28 nm, the Freedom U500 platform is well suited for machine learning, storage, and networking applications. The platform also supports standard high-speed peripherals including PCIe 3.0, USB 3.0, Gigabit Ethernet, and DDR3/DDR4.
  • Freedom E300 Series: The Freedom Everywhere (E) family is designed for embedded microcontroller, IoT, and wearables markets. Designed in TSMC 180 nm and architected to have minimal area and power, the Freedom E300 platform features efficient RISC-V cores with support for RISC-V compressed instructions that have been shown to reduce code size by up to 30%.

Full FPGA models of each SoC are now available. Visit dev.sifive.com for more information.

Source: SiFive

New Micro Buzzers for Portable Applications

CUI’s Components Group recently expanded its micro buzzer product line. Housed in surface-mount packages as small as 4 mm × 4 mm, the three new models—CMT 4023S SMT, CMT 5023S SMT, and CPT 9019S SMT—are well suited for a wide variety of portable electronic systems.
UCI buzzer

The CMT 4023S SMT and CMT 5023S SMT magnetic transducer buzzers are 4 mm × 4 mm and 5 mm × 5 mm, respectively. They have a rated voltage of 3 V and a rated frequency of 4 kHz.

The 9 mm × 9 mm CPT 9019S SMT features piezoelectric technology and a profile depth of 1.9 mm. The series delivers a maximum peak-to-peak voltage of 25 V, a rated frequency of 4 kHz, and an SPL of 65 dB. Its operating temperature range is –30°C to 70°C.

The CMT 4023S SMT, CMT 5023S SMT, and CPT 9019S SMT are externally driven and suitable for use in designs requiring reflow solder assembly for high-volume production. They are available immediately with prices starting at $1.08 per unit in 1,000-piece quantities.

Source: CUI

High-Performance Secure Shell Solution for MCU-Based Systems

SEGGER recently introduced its emSSH software library for the purpose of creating secure connections between a client and a server, typically over a TCP/IP connection. The library is well suited for applications such as secure remote controls.

emSSH includes all modules required for implementing SSH cryptographic networks. They are provided as source code and thus give complete code control. emSSH also delivers full transparency, which eliminates concerns about possible security issues. Its flexible crypto engine can make use of hardware acceleration (if available), and it comes with a powerful API.

Hardware and transport independent, emSSH integrates with SEGGER’s em-bOS/IP and third-party stacks via the standard socket interface. You can configure the emSSH library to meet a variety of speed or size requirements. Unused features can be excluded and additional features can easily be added. The complete software package is written in ANSI C and it’s both compiler and target independent.

Source: SEGGER Microcontroller

RF-LORA Module for the IoT

RF Solutions’s RF-LORA module is a high-performance radio module delivered in a compact 23 mm × 20 mm format. Intended for Internet of Things (IoT) applications, the RF-LORA module delivers Semtech’s LoRa technology for IoT applications.RF-LORA promo image v2 copy

The RF-LORA’s specs and features:

  • Up to 16 km, spread-spectrum communication and high interference immunity within minimum current consumption
  • Semtech SX1272 LoRa chip.
  • Built-in preamble detection
  • Available in SMT and DIL packages

Source: RF Solutions