MCUs and Processors Vie for Embedded Mindshare

Performance Push

Today’s crop of high-performance microcontrollers and embedded processors provide a rich continuum of features, functions and capabilities. Embedded system designers have many choices in both categories but the dividing line between the two can be blurry.

By Jeff Child, Editor-in-Chief

At one time the world of microcontrollers and the world of microprocessors were clearly separate. That’s slowly changed over the years as the high-performance segment of microcontrollers have become more powerful. And the same time, embedded processors have captured ever more mindshare and market share that used to be exclusively owned by the MCU camp. The lines blurred even further once most all MCUs started using Arm-based processor cores.

All the leading MCU vendors have a high-performance line of products, some in the 200 MHz and up range. Moreover, some application-specific MCU offerings are designed specifically for the performance needs of a particular market segment—automotive being the prime example. In some cases, these high end MCUs are vying for design wins against embedded processors that meet the same size, weight and power requirements as MCUs. In this article, we’ll examine some of the latest and greatest products and technologies on both sides.

High Performance MCU

An example of an MCU vendor’s high-performance line of products is Cypress Semiconductor’s FM4. FM4 is a portfolio of 32-bit, general-purpose, high performance MCUs based on the Arm Cortex-M4 processor with FPU and DSP functionality. FM4 microcontrollers operate at frequencies up to 200 MHz and support a diverse set of on-chip peripherals for motor control, factory automation and home appliance applications. The portfolio delivers low-latency, reliable, machine-to-machine (M2M) communication required for Industry 4.0 using network-computing technologies to advance design and manufacturing.

The FM4 MCU supports an operating voltage range of 2.7 V to 5.5 V. The devices incorporate 256 KB to 2 MB flash and up to 256 KB RAM. The fast flash memory combined with a flash accelerator circuit (pre-fetch buffer plus instruction cache) provides zero-wait-state operation up to 200 MHz. A standard DMA and an additional descriptor-based DMA (DSTC), each with an independent bus for data transfer, can be used to further offload the CPU. Figure 1 shows the FM4-216-ETHERNET, a development platform for developing applications using the Arm Cortex-M4-based FM4 S6E2CC MCU.

Figure 1
The FM4-216-ETHERNET is a development platform for developing applications using the Arm Cortex-M4-based FM4 S6E2CC MCU.

The high-performance line of MCUs from ST Microelectronics is its STM32H7 series. An example product from that series is the STM32H753 MCU with Arm’s highest-performing embedded core (Cortex-M7). According to ST Micro it delivers a record performance of 2020 CoreMark/856 DMIPS running at 400 MHz, executing code from embedded flash memory.

Other innovations and features implemented by ST further boost performance.These include the Chrom-ART Accelerator for fast and efficient graphical user-interfaces, a hardware JPEG codec that allows high-speed image manipulation, highly efficient Direct Memory Access (DMA) controllers, up to 2 MB of on-chip dual-bank flash memory with read-while-write capability, and the L1 cache allowing full-speed interaction with off-chip memory. Multiple power domains allow developers to minimize the energy consumed by their applications, while plentiful I/Os, communication interfaces, and audio and analog peripherals can address a wide range of entertainment, remote-monitoring and control applications.

Last year STMicro announced its STM32H7 high-performing MCUs are designed with the same security concepts as the Platform Security Architecture (PSA) from Arm announced at that time. This PSA framework on the STM32H7 MCUs are combined with STM32-family enhanced security features and services. ST’s STM32H7 MCU devices integrate hardware-based security features including a True Random-Number Generator (TRNG) and advanced cryptographic processor, which will simplify protecting embedded applications and global IoT systems against attacks like eavesdropping, spoofing or man-in-the-middle interception.

MCU Runs Linux OS

One dividing line that remains between MCUs and microprocessors is their ability to run major operating systems. While most embedded processors can run OSes like Linux, most MCUs lack the memory architecture required to do so. Breaking that barrier, in February MCU vendor Microchip Technology unveiled a System on Module (SOM) featuring the SAMA5D2 microprocessor. The ATSAMA5D27-SOM1 contains the recently released ATSAMA5D27C-D1G-CU System in Package (SiP) (Figure 2).

Figure 2
The Arm Cortex-A5-based SAMA5D2 SiP is available in three DDR2 memory sizes (128 Mb, 512 Mb and 1 Gb) and optimized for bare metal, RTOS and Linux implementation

The SOM simplifies design by integrating the power management, non-volatile boot memory, Ethernet PHY and high-speed DDR2 memory onto a small, single-sided PCB. There is a great deal of design effort and complexity associated with creating an industrial-grade MPU-based system running a Linux operating system. The SOM integrates multiple external components and eliminates key design challenges around EMI, ESD and signal integrity. …

Read the full article in the August 337 issue of Circuit Cellar

Don’t miss out on upcoming issues of Circuit Cellar. Subscribe today!

Note: We’ve made the October 2017 issue of Circuit Cellar available as a free sample issue. In it, you’ll find a rich variety of the kinds of articles and information that exemplify a typical issue of the current magazine.

September Circuit Cellar: Sneak Preview

The September issue of Circuit Cellar magazine is coming soon. Clear your decks for a new stack of in-depth embedded electronics articles prepared for you to enjoy.

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Here’s a sneak preview of September 2018 Circuit Cellar:

MOTORS, MOTION CONTROL AND MORE

Motion Control for Robotics
Motion control technology for robotic systems continues to advance, as chip- and board-level solutions evolve to meet new demands. These involve a blending of precise analog technologies to control position, torque and speed with signal processing to enable accurate, real-time motor control. Here, Circuit Cellar’s Editor-in-Chief, Jeff Child, looks the latest technology and product advances in motion control for robotics.

Electronic Speed Control (Part 3)
Radio-controlled drones are one among many applications that depend on the use of an Electronic Speed Controller (ESC) as part of its motor control design. After observing the operation of a number of ESC modules, in this part Jeff Bachiochi focuses in more closely on the interaction of the ESC with the BLDC motor.

BUILDING CONNECTED SYSTEMS

Product Focus: IoT Gateways
IoT gateways are a smart choice to facilitate bidirectional communication between IoT field devices and the cloud. Gateways also provide local processing and storage capabilities for offline services as well as near real-time management and control of edge devices. This Product Focus section updates readers on these technology trends and provides a product gallery of representative IoT gateways.

Wireless Weather Station
Integrating wireless technologies into embedded systems has become much easier these days. In this project article, Raul Alvarez Torrico describes his home-made wireless weather station that monitors ambient temperature, relative humidity, wind speed and wind direction, using Arduino and a pair of cheap Amplitude Shift Keying (ASK) radio modules.

FOCUS ON ANALOG AND POWER TECHNOLOGY

Frequency Modulated DDS
Prompted by a reader’s query, Ed became aware that you can no longer get crystal oscillator modules tuned to specific frequencies. With that in mind, Ed set out to build a “Channel Element” replacement around a Teensy 3.6 board and a DDS module. In this article, Ed Nisley explains how the Teensy’s 32-bit datapath and 180 MHz CPU clock affect the DDS frequency calculations. He then explores some detailed timings.

Power Supplies / Batteries
Sometimes power decisions are left as an afterthought in system designs. But your choice of power supply or battery strategy can have a major impact on your system’s capabilities. Circuit Cellar’s Editor-in-Chief, Jeff Child, dives into the latest technology trends and product developments in power supplies and batteries.

Murphy’s Laws in the DSP World (Part 3)
Unpredictable issues crop up when you move from the real world of analog signals and enter the world of digital signal processing (DSP). In Part 3 of this article series, Mike Smith and Mai Tanaka focuses on strategies for how to—or how to try to—avoid Murphy’s Laws when doing DSP.

SYSTEM DESIGN ISSUES IN VIDEO AND IMAGING

Virtual Emulation for Drones
Drone system designers are integrating high-definition video and other features into their SoCs. Verifying the video capture circuitry, data collection components and UHD-4K streaming video capabilities found in drones is not trivial. In his article, Mentor’s Richard Pugh explains why drone verification is a natural fit for hardware emulation because emulation is very efficient at handling large amounts of streamed data.

LIDAR 3D Imaging on a Budget
Demand is on the rise for 3D image data for use in a variety of applications, from autonomous cars to military base security. That has spurred research into high precision LIDAR systems capable of creating extremely clear 3D images to meet this demand. Learn how Cornell student Chris Graef leveraged inexpensive LIDAR sensors to build a 3D imaging system all within a budget of around $200.

AND MORE FROM OUR EXPERT COLUMNISTS

Velocity and Speed Sensors
Automatic systems require real-life physical attributes to be measured and converted to electrical quantities ready for electronic processing. Velocity is one such attribute. In this article, George Novacek steps through the math, science and technology behind measuring velocity and the sensors used for such measurements.

Recreating the LPC Code Protection Bypass
Microcontroller fuse bits are used to protect code from being read out. How well do they work in practice? Some of them have been recently broken. In this article Colin O’Flynn takes you through the details of such an attack to help you understand the realistic threat model.

High-Performance MCUs Serve IoT Device Needs

STMicroelectronics has added two new lines to its STM32 MCU family, the STM32F7x0 and H7x0 Value Line. The MCUs are aimed at enabling system designers to create affordable performance-oriented systems including real-time IoT devices, without compromising features or cyber protection.

These new lines trim embedded flash to the essential, still allowing secure boot, sensitive code and real-time routines to run safely on-chip, leveraging access times over 25 times faster than for external Flash (for cache miss). If needed, applications can scale-up either by adding off-chip serial or parallel (up to 32-bit) memories and leveraging the MCUs’ broad external interfaces and eXecute in Place (XiP) capability, or by porting to other pin-to-pin compatible STM32F7 or STM32H7 MCU lines, with up to 2 MB Flash and up to 1 MB RAM, supported by the same ecosystem with the same easy-to-use tools.

The Value Lines retain powerful STM32F7 and H7 features, such as the state-of-the-art peripherals, hardware accelerators, and the real-time architecture with ultra-fast internal buses, short interrupt latency, and fast (approximately 1 ms) boot-up. The MCUs are also energy efficient, with flexible power modes, gated power domains, and on-chip power management that simplify design and reduce BOM cost.

With execution performance up to 2020 CoreMark at the heart of a secure and power-efficient architecture, the new Value Line devices are the entry point to IoT innovation in medical, industrial, and consumer applications. CoreMark is the EEMBC standardized benchmark for embedded-CPU performance. With up to 125°C as the maximum junction temperature, developers can leverage the full core and peripherals performance even when ambient temperature increases.

The entry-level STM32F730 delivers 1082 CoreMark performance running at 216MHz aided by ST’s unique ART Accelerator for zero-wait-state execution from Flash. Features include cryptographic hardware acceleration, a USB 2.0 High Speed port with PHY, and a CAN interface. There is a 64Kbyte Flash, 8KByte Instruction and data caches for high-performance execution from internal or external memories, 256KB of system RAM and 16 KB plus 64 KB of Tightly Coupled Memory (TCM) for the most critical routines and data.

The STM32F750 adds a TFT-LCD controller with ST’s proprietary Chrom-ART Graphics Accelerator. It has hardware acceleration for hash algorithms, two CAN interfaces, an Ethernet MAC, camera interface, and two USB 2.0 interfaces with Full Speed PHY. There are 64Kbytes of Flash, 4Kbyte instruction and 4 KB data caches, 320 KB of system RAM and 16 KB plus 64 KB TCM.

The high-end STM32H750 delivers 2020 CoreMark performance at 400 MHz and adds a hardware JPEG coder/decoder to the TFT controller and Chrom-ART Accelerator for even faster GUI performance. There is also a CANFD port and additional CANFD with time-trigger capability and best-in-class operational amplifiers and 16-bit ADCs running at up to 3.6 Msample/s. The 128 KB flash, 16 KB instruction and data caches, 864 KB system RAM and the 64 KB+128 KB of TCM all feature ECC (Error Correction Code) for safe execution from internal or external memory.

The STM32F730, STM32F750, and STM32H750 Value Line MCUs are in production, in various LQFP and BGA package options from 64-pin to 240-pin. Prices start from $1.64 for the STM32F730, $2.39 for the STM32F750 and $2.69 for the STM32H750 for orders of 1,000 pieces.

STMicroelectronics | www.st.com

Compact MCU Offers Enhanced Security Features

Maxim Integrated Products has announced the MAX32558 “DeepCover” family of secure microcontrollers that provide advanced cryptography, secure key storage and tamper detection in a 50% smaller package. As electronic products become smaller and increasingly connected, there is a growing threat to sensitive information and privacy, requiring manufacturers to keep security top of mind when designing their devices. While designers should prevent security breaches at the device level, they often struggle with the tradeoff of enhanced security with minimized board space, as well as the cost of design complexity and meeting time to market goals.
The MAX32558 DeepCover Arm Cortex-M3 flash-based secure microcontroller solves these challenges by delivering strong security in a small footprint while simplifying design integration and speeding time to market. It integrates several security features into a small package, including secure key storage, a secure bootloader, active tamper detection and secure cryptographic engines. It also supports multiple communications channels such as USB, serial peripheral interface (SPI), universal asynchronous receiver-transmitter (UART) and I2C, making it ideal for a wide range of applications. Maxim’s long-standing reputation and experience in payment terminal certifications as well as its established support and technology can help streamline the certification process for customers, reducing the process up to 6 months’ time (rather than the typical 12 to 18 months).

Security:Features:

  • Shields sensitive data by providing the most secure key storage available
  • Offers secure bootloader, active tamper detection and secure cryptographic engines
  • Compliant with Federal Information Processing Standard (FIPS) 140-2 L3&4 certification

Compared to a secure authenticator, the MAX32558 provides 30x more general-purpose input/output (GPIO) in the same PCB footprint (4.34 mm x 4.34 mm) wafer-level package (WLP). The closest competitor, meanwhile, offers a device with similar features but in a much larger package (8 mm x 9 mm ball-grid array 121 (BGA121)). The devices reduces footprint by embedding a number of security features to address point-of-sale Payment Card Industry (PCI) pin transaction security (PTS) requirements, as well as several analog interfaces. It provides 512 KB of internal flash and 96 KB of internal SRAM

Easy design integration is enabled by a complete software framework including real-time operating system (RTOS) integration and code examples in evaluation kit. Code can be easily ported from one device to another as it shares the same API software library as the rest of the product family. A pre-certified Europay, Mastercard and Visa (EMV)-L1 stack for smartcard interface is provided. Extensive documentation and code is provided for managing the device lifecycle, such as secure firmware signing and device personalization. The MAX32558 is available at Maxim’s website for $3.80 (1,000-up).

Maxim Integrated | www.maximintegrated.com

Tuesday’s Newsletter: Microcontroller Watch

Coming to your inbox tomorrow: Circuit Cellar’s Microcontroller Watch newsletter. Tomorrow’s newsletter keeps you up-to-date on latest microcontroller news. In this section, we examine the microcontrollers along with their associated tools and support products.

Bonus: We’ve added Drawings for Free Stuff to our weekly newsletters. Make sure you’ve subscribed to the newsletter so you can participate.

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Our weekly Circuit Cellar Newsletter will switch its theme each week, so look for these in upcoming weeks:

IoT Technology Focus. (8/21) Covers what’s happening with Internet-of-Things (IoT) technology–-from devices to gateway networks to cloud architectures. This newsletter tackles news and trends about the products and technologies needed to build IoT implementations and devices.

Embedded Boards.(8/28) The focus here is on both standard and non-standard embedded computer boards that ease prototyping efforts and let you smoothly scale up to production volumes.

Analog & Power. (9/4) This newsletter content zeros in on the latest developments in analog and power technologies including DC-DC converters, AD-DC converters, power supplies, op amps, batteries and more.

Pitfalls of Filtering Pulsed Signals

Waveform Woes

Filtering pulsed signals can be a tricky prospect. Using a recent customer problem as an example, Robert highlights various alternative approaches and describes the key concepts involved. Simulation results are provided to help readers understand what’s going on.

By Robert Lacoste

Welcome back to the Darker Side. A couple of months ago, one of our customers was having trouble with its project and called us for help. As is often the case, the problem was more a misunderstanding of the underlying concepts than any kind of hardware or software issues. We helped him, but because the same issue could jeopardize your own projects I thought it would be a nice topic for this column.

The Project

What is it about? Of course, I won’t be able share the details of our customer’s project, but I will describe a close example. Let’s imagine you need to build an ultrasonic ranging system. Just as bats do, you want to transmit short bursts of ultrasound, then listen for echoes. As you probably know, the time between transmission and reception divided by twice the speed of sound will give you the distance of the obstacle.

Moreover, the shift in frequency between transmitted and received bursts will give you the relative speed of this obstacle, thanks to the so-called Doppler shift. Ok, but how will you design such a ranging device? First, you’ll need to generate and transmit bursts of sine waves—also called tone bursts—with the proper ultrasonic frequency, say 40 kHz. That’s easy to do even with a pair of trusty NE555 chips or NAND gates, or maybe with a microcontroller if you prefer dealing code rather than a soldering iron. These bursts will need to be as short as possible—maybe 1 ms or so—because this will improve the distance resolution.

The transmit side is easy, but the receiver will be a little more complex. In real life, the received signal will have a very low amplitude and probably plenty of added noise. This is especially true if you consider that the Doppler shift could be significant, meaning with fast-moving objects. In that case you will not know the exact frequency of the burst you should detect.

Figure 1
Shown here is a basic ultrasonic meter. A narrow band-pass filter, tuned to the received frequency, allows you to reduce perturbations and noise. But does this work?

One possible architecture to avoid this problem, while minimizing noise, could be the one illustrated on Figure 1. First, do a spectrum analysis of the received signal. Because this signal contains noise plus the received ultrasonic echo, its frequency spectrum will show a peak at the frequency of the received ultrasonic carrier. Therefore, you can measure this actual reception frequency. Assume it is 40.5 kHz due to Doppler shift. You can use this information to tune a very selective band-pass filter, which will isolate the received ultrasonic burst from any other noise. Why not a 40.5 kHz +/-100 Hz filter? You will then recover a clean version of the received pulse and measure the time difference between transmission and reception with a detector and a time counter. Brilliant idea, isn’t it? If you agree, then please read on. This was the concept used by our customer, and unfortunately it doesn’t work! At least not as described. In this article I will explain why, using some easy to understand simulations and as little math as possible. So, don’t’ be afraid. Come with me to the Darker Side of pulsed signals.

Digital Version

Before going into the explanation, I need to present you an alternative version of this intended receiver. Because you are a reader of Circuit Cellar, you know that developing such a design would be far easier using digital signal processing than trying to build analog spectrum analyzers and precisely tuned filters. The digital equivalent of this receiver is illustrated on Figure 2. Just compare it with the former, you will find the same concepts.

Figure 2
Here’s a digital version of the same concept shown in Figure 1. All the yellow functions can be executed on a digital processor (fast microcontroller, digital signal processor, FPGA or anything else).

Here the received signal is preamplified and directly digitized with a properly selected analog-to-digital converter (ADC). Its frequency spectrum can then be calculated with a Fourier Transform, using the well-known Fast Fourier Transform (FFT) algorithm, for example. The frequency peak can then be searched into this spectrum. Then a narrow band-pass filter can be created and tuned to this frequency and the filtered signal can be calculated. …

Read the full article in the August 337 issue of Circuit Cellar

Don’t miss out on upcoming issues of Circuit Cellar. Subscribe today!

Note: We’ve made the October 2017 issue of Circuit Cellar available as a free sample issue. In it, you’ll find a rich variety of the kinds of articles and information that exemplify a typical issue of the current magazine.

Tuesday’s Newsletter: Analog & Power

Coming to your inbox tomorrow: Circuit Cellar’s Analog & Power newsletter. Tomorrow’s newsletter content zeros in on the latest developments in analog and power technologies including ADCs, DACs, DC-DC converters, AD-DC converters, power supplies, op amps, batteries and more.

Bonus: We’ve added Drawings for Free Stuff to our weekly newsletters. Make sure you’ve subscribed to the newsletter so you can participate.

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Our weekly Circuit Cellar Newsletter will switch its theme each week, so look for these in upcoming weeks:

Microcontroller Watch. (8/14) This newsletter keeps you up-to-date on latest microcontroller news. In this section, we examine the microcontrollers along with their associated tools and support products.

IoT Technology Focus. (8/21) Covers what’s happening with Internet-of-Things (IoT) technology–-from devices to gateway networks to cloud architectures. This newsletter tackles news and trends about the products and technologies needed to build IoT implementations and devices.

Embedded Boards.(8/28) The focus here is on both standard and non-standard embedded computer boards that ease prototyping efforts and let you smoothly scale up to production volumes.

IAR Systems Updates Dev Tools for Renesas RX MCUs

IAR Systems has released version 4.10 of the development toolchain IAR Embedded Workbench for Renesas RX. The new version includes several capabilities which enable developers to further ensure code quality and make debugging more efficient for embedded applications based on Renesas RX microcontrollers.
IAR Embedded Workbench for Renesas RX includes the IAR C/C++ Compiler that offers Renesas RX ABI compliance. With version 4.10, the toolchain includes compliance with the latest C language standard ISO/IEC 9899:2011 as well as the latest C++ standard ISO/IEC 14882:2014. The compiler now also supports stack protection.

To make debugging more efficient in IAR Embedded Workbench for Renesas RX, the new version adds support for the advanced on-chip debugging E2 emulator from Renesas. And for developers using IAR Embedded Workbench for Renesas RX with the static analysis tool C-STAT, they can now benefit from 20 new checks, some of which are enabled by default to further ensure code quality.

IAR Embedded Workbench for Renesas RX is available at several different editions to suit different needs, including a functional safety edition certified by TÜV SÜD according to IEC 61508, EN 50128, ISO 26262 and IEC 62304. More information about the tools and trial versions can be found at www.iar.com/iar-embedded-workbench/tools-for-rx/.

IAR Systems | www.iar.com

MCUs Bring Enhanced Security to IoT Systems

Microchip has announced its SAM L10 and SAM L11 MCU families addressing the growing need for security in IoT applications. The new MCU families are based on the Arm Cortex-M23 core, with the SAM L11 featuring Arm TrustZone for Armv8-M, a programmable environment that provides hardware isolation between certified libraries, IP and application code. Security features on the MCUs include tamper resistance, secure boot and secure key storage. These, combined with TrustZone technology, protect applications from both remote and physical attacks.

In addition to TrustZone technology, the SAM L11 security features include an on-board cryptographic module supporting Advanced Encryption Standard (AES), Galois Counter Mode (GCM) and Secure Hash Algorithm (SHA). The secure boot and secure key storage with tamper detection capabilities establish a hardware root of trust. It also offers secure bootloader for secure firmware upgrades.

Microchip has partnered with Trustonic, a member of Microchip’s Security Design Partner Program, to offer a comprehensive security solution framework that simplifies implementation of security and enables customers to introduce end products faster. Microchip has also partnered with Secure Thingz and Data I/O Corporation to offer secure provisioning services for SAM L11 customers that have a proven security framework.

Both MCU families offer Microchip’s latest-generation Peripheral Touch Controller (PTC) for capacitive touch capabilities. Designers can easily add touch interfaces that provide an impressively smooth and efficient user experience in the presence of moisture and noise while maintaining low power consumption. The touch interface makes the devices ideal for a myriad of automotive, appliance, medical and consumer Human Machine Interface (HMI) applications.

The SAM L10 and SAM L11 Xplained Pro Evaluation Kits are available to kick-start development. All SAM L10/L11 MCUs are supported by the Atmel Studio 7 Integrated Development Environment (IDE), IAR Embedded Workbench, Arm Keil MDK as well as Atmel START, a free online tool to configure peripherals and software that accelerates development. START also supports TrustZone technology to configure and deploy secure applications. A power debugger and data analyzer tool are available to monitor and analyze power consumption in real time and fine tune the consumption numbers on the fly to meet application needs. Microchip’s QTouch Modular Library, 2D Touch Surface Library and QTouch Configurator are also available to simplify touch development.

Devices in the SAM L10 series are available starting at $1.09 (10,000s). Devices in the SAM L11 series are available starting at $1.22 (10,000s).

Microchip Technology | www.microchip.com

Bonus Newsletter Tomorrow: PCB Design

Coming to your inbox tomorrow: July has a 5th Tuesday . That’s means there’s an extra Newsletter this month! The bonus topic is PCB Design. The process of PCB design is always facing new complexities. Rules-based autorouting, chips with higher lead counts and higher speed interconnections are just a few of the challenges forcing PCB design software to keep pace. This newsletter updates you on the latest happenings in this area.

Also, we’ve added Drawings for Free Stuff to our weekly newsletters. Make sure you’ve subscribed to the newsletter so you can participate.

Already a Circuit Cellar Newsletter subscriber? Great!
You’ll get your PCB Design newsletter issue tomorrow.

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Our weekly Circuit Cellar Newsletter switches its theme each week, so look for these in upcoming weeks:

Analog & Power. (8/7) This newsletter content zeros in on the latest developments in analog and power technologies including DC-DC converters, AD-DC converters, power supplies, op amps, batteries and more.

Microcontroller Watch. (8/14) This newsletter keeps you up-to-date on latest microcontroller news. In this section, we examine the microcontrollers along with their associated tools and support products.

IoT Technology Focus. 8/21) Covers what’s happening with Internet-of-Things (IoT) technology–-from devices to gateway networks to cloud architectures. This newsletter tackles news and trends about the products and technologies needed to build IoT implementations and devices.

Embedded Boards. (8/28) This newsletter content focuses on both standard and non-standard embedded computer boards that ease prototyping efforts and let you smoothly scale up to production volumes.

Signature Analyzer Uses NXP MCU

Scope-Free Tester

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.

FIGURE 1
This is a block diagram of the AC signal generation and Voltage/Current monitoring circuit.

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.

Signature Analysis

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

Don’t miss out on upcoming issues of Circuit Cellar. Subscribe today!

Note: We’ve made the October 2017 issue of Circuit Cellar available as a free sample issue. In it, you’ll find a rich variety of the kinds of articles and information that exemplify a typical issue of the current magazine.

Next Newsletter: Embedded Boards

Coming to your inbox tomorrow: Circuit Cellar’s Embedded Boards newsletter. Tomorrow’s newsletter content focuses on both standard and non-standard embedded computer boards that ease prototyping efforts and let you smoothly scale up to production volumes.

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Our weekly Circuit Cellar Newsletter will switch its theme each week, so look for these in upcoming weeks:

July has a 5th Tuesday, so we’re bringing you a bonus newsletter:
PCB Design (7/31) 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 tools are addressing the broader picture of the PCB design process. This newsletter looks at the latest technology trends and product developments in PCB design tools.

Analog & Power. (8/7) This newsletter content zeros in on the latest developments in analog and power technologies including DC-DC converters, AD-DC converters, power supplies, op amps, batteries and more.

Microcontroller Watch (8/14) This newsletter keeps you up-to-date on latest microcontroller news. In this section, we examine the microcontrollers along with their associated tools and support products.

IoT Technology Focus. (8/21) Covers what’s happening with Internet-of-Things (IoT) technology–-from devices to gateway networks to cloud architectures. This newsletter tackles news and trends about the products and technologies needed to build IoT implementations and devices.

Verifying Code Readout Protection Claims

Think Like an Attacker

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 discusses a few threats against code readout and looks at verifying some of those claimed levels.

By Colin O’Flynn

You’ve got your latest and greatest IoT toaster designed, and you’re looking to move forward with production. But one thing concerns you: How do you know this stellar code isn’t going to be cloned as soon as you release it to the market?

You turn to the firmware protection features of your chosen microcontroller, but how good is it? This article can’t hope to answer that question in general, rather it will instead give you a short example of how to help answer that question for any specific microcontroller.

In particular, it will teach you to “think like an attacker” when reading through datasheets. Look for small loopholes that could have big consequences, and you will have a much better time navigating the landscape of potential attacks.

Know What’s Out There

One of the most important things is to keep an eye out for new and interesting attacks against these devices. In my January 2018 article (Circuit Cellar 330) I described how there is a published attack against some of the NXP LPC devices, which makes it very easy to unlock them. You can see the presentation entitled “Breaking Code Read Protection on the NXP LPC-family Microcontrollers” by Chris Gerlinsky which describes this attack. Another recent one is an attack against STMicroelectronics’ STM32F0 devices entitled “Shedding Too Much Light on a Microcontroller’s Firmware Protection” by Johannes Obermaier and Stefan Tatschner. That one is a little more limited, but still has some interesting information regarding potential security attacks.

I’m hoping to distill some of these attacks down into common problems, which will help you close a few loopholes before someone rips off your IoT toaster design. At least now if it fails in the marketplace you have no one to blame but yourself.
To give you something concrete to read (and for me to reference), I’ve chosen to use the ST STM32F303 series because it’s a device I’ve been using myself lately. I’m not going to be revealing any unknown vulnerabilities—so if you’re reading this from your office at  STMicroelectronics, no need to sweat. It also has some pretty common configuration options, so makes for a nice reference you can apply to a range of other devices.

ST Read Protection (RDP)

The first step when you are looking at a new device should be to very carefully inspect the security or debug lock protection portion of the datasheet. They will typically go into a fair amount of detail around how the protection mechanism works.
The STM32F3 Reference Manual (RM0316) has this split into two sections. Section 5, entitled “Option byte description” provides information about how the flags are stored in flash. Section 4.3 entitled “Memory Protection” details how this is actually used to protect the code in your device.

Table 1
This excerpt from the datasheet shows how the flash memory read protection levels are defined for the STM32F3 device.

The two important pieces of information for us are replicated in Table 1 and
Table 2. They are the flash memory protection levels, and the associated access allowed at each level. The RDP byte is a special “option byte”, which is the value of a specific location in flash memory. Note the scheme they have chosen uses two bytes, where one is always programmed to be the complement of the other byte. This is presumably used for error checking, and if a byte is not matched with a complement, an error flag is set.

Table 2
Code protection levels 1 and 2 have differing protection abilities. This excerpt from the datasheet shows where flash memory can be read/written/executed from.

Right away you should notice that this scheme does not fall victim to the same problem as the LPC attack I talked about before. In particular the LPC attack exploited the fact a fault or glitch could corrupt the flag value, which caused the CPU to disable the protection.

With the STM32F303, these invalid levels will all map to Protection Level 1. This protection level does not allow external flash access, which “should” be a good sign. The highest protection level also claims to be impossible to remove, but if we could corrupt the value of the option bytes in memory we could downgrade from Protection Level 2 to Protection Level 1. In fact, this “downgrade” is exactly what was presented by Obermaier & Tatschner. The downgrade used a chip decapsulation and light to flip the bits, which is relatively invasive. Other fault attacks (such as voltage or EM) might work but would require investigation before assuming that. Such temporary fault attacks would require the value is read and latched.

But as a good designer, you should assume such faults could be made possible. In this case it would be possible to “downgrade” the device from Protection Level 2 to Protection Level 1. So, what happens if an attacker performed this downgrade? That takes us into the second part of this article. …

Read the full article in the July 336 issue of Circuit Cellar

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Note: We’ve made the October 2017 issue of Circuit Cellar available as a free sample issue. In it, you’ll find a rich variety of the kinds of articles and information that exemplify a typical issue of the current magazine.

August Circuit Cellar: Sneak Preview

The August issue of Circuit Cellar magazine is coming soon. Be on the lookout for a whole shipload of top-notch embedded electronics articles for you to enjoy.

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Here’s a sneak preview of August 2018 Circuit Cellar:

FPGAs REDEFINE THE DEFINITION OF “SYSTEM”

FPGA System Design
Long gone now are the days when FPGAs were thought of as simple programmable circuitry for interfacing and glue logic. Today, FPGAs are powerful system chips with on-chip processors, signal processing functionality and rich offerings or high-speed connectivity. Here, Circuit Cellar’s Editor-in-Chief, Jeff Child, looks at the latest technology and trends in FPGA system design.

Managing FPGA Design Complexity
Modern FPGAs can contain millions of logic gates and thousands of embedded DSP processors allowing FPGA hardware designers to create extremely sophisticated and complex application-specific hardware functions. In this article, Pentek’s Bob Sgandurra explores how today’s FPGA technology has revamped the roles of both hardware and software engineers as well as how dealing with on-chip IP adds new layers of complexity.

HIGH-INTEGRATION AT THE CHIP-
AND BOARD-LEVEL

Product Focus: Small and Tiny Embedded Boards
An amazing amount of computing functionality can be squeezed on to a small form factor board these days. These company—and even tiny—board-level products meet the needs of applications where extremely low SWaP (size, weight and power) beats all other demands. This Product Focus section updates readers on this technology trend and provides a product album of representative small and tiny embedded boards.

Microcontrollers and Processors
Today’s crop of microcontrollers and embedded processors provide a rich continuum of features, functions and capabilities. It’s hard to tell anymore where the dividing line is, especially when a lot of them use the same CPU cores. Circuit Cellar’s Editor-in-Chief, Jeff Child, delves into the technology and product trends of MCUs and embedded processors.

CAN’T STOP THE SIGNAL

Murphy’s Laws in the DSP World (Part 2)
Many unexpected issues come into play when you move from the real world of analog signals and enter the world of digital signal processing (DSP). Part 2 of this article series by Michael Smith, Mai Tanaka and Ehsan Shahrabi Farahani charges forward introducing “Murphy’s Laws of DSP” #7, #8 and #9 and looks at the spectral analysis of DSP signals.

Signature Analyzer Uses NXP MCU
Doing a signature analysis of a signal used to require an oscilloscope to display your results. In this article, Brian Millier shows how you can build a free-standing tester that uses mostly just the internal peripherals of an NXP ARM microcontroller. He described how the tester operates and how he implemented it using a Teensy 3.5 development module and an intelligent 4.3-inch TFT touch-screen display.

Pitfalls of Filtering Pulsed Signals
Filtering pulsed signals can be a tricky prospect. Using a recent customer implementation as an example, Robert Lacoste highlights various alternative approaches and describes the key concepts involved. Simulation results are provided to help readers understand what’s going on.

PROJECT-BASED STORIES WITH ALL THE DETAILS

Electronic Speed Control (Part 2)
In Part 1, Jeff Bachiochi discussed the mechanical differences between DC brushed and brushless DC (BLDC) motors. This time he dives into basics of an Electronic Speed Controller’s operations and its circuitry. And all this is illustrated via his ESC-based project that uses a Microchip PIC MCU.

Build an Audio Response Light Display
Light shows have been a part of entertainment situations seemingly forever, but the technology has evolved over time. These light shows have their origin in the primitive “light organs” of the 1960s in which each spectral band had its own color that pulsed in intensity with audio amplitudes within its range of frequencies. In this article, Devlin Gualtieri discusses his circuit design that implements a light organ using today’s IC and LED technologies.

AND MORE FROM OUR EXPERT COLUMNISTS

Internet of Things Security (Part 4)
In this next part of his article series on IoT security, Bob Japenga looks at how checklists and the common criteria framework can help us create more secure IoT devices. He covers how to create a list of security assets and to establish threat checklists that identify all the threats to your security assets.

Thermoelectric Cooling (Part 2)
In Part 1 George Novacek described how he built a test chamber using some electronics combined with components salvaged from his thermoelectric water cooler. To confirm his test results, he purchased another thermoelectric cooler and repeated the tests. In Part 2 he covers the results of these tests along with some theoretical performance calculations.

Bluetooth SIG Appoints New Associate Member Directors

The Bluetooth Special Interest Group (SIG) announced that Peter Liu from Bose and Ron Wong from Cypress Semiconductor will be joining the board of directors of the Bluetooth SIG as Associate Member Directors. The Bluetooth SIG Board of Directors is responsible for the governance of the organization and plays a vital role in driving the expansion of Bluetooth technology to address the needs of a growing number of consumer and commercial markets. Both will serve a two-year term starting in July 2018.

Peter Liu (left) is an Architect of Wearable Systems at Bose, leading programs and creating technology platforms for hearables. Previously, he led the Advanced Electronic Systems group in Bose Consumer Headphones to deliver enabling technologies and architectures for the wireless and noise-cancelling headphones enjoyed today by audio enthusiasts worldwide. Peter delights in bringing new experiences to life by drawing upon his expertise and network cultivated over a career spanning semiconductors and end-products in infrastructure, cellular and consumer electronics industries.

Ron Wong (right) is Director, Product Marketing in the Microcontroller & Connectivity Division of Cypress Semiconductor and manages connectivity software solutions that help companies bring innovative, low-power connected products to market. He is responsible for defining and driving Cypress’ Internet of Things (IoT) product portfolio, including Bluetooth software and Wireless Connectivity for Embedded Devices (WICED) development kits. A veteran of wireless technology, Ron has more than 25 years of experience in wireless communications including 18 years in Bluetooth technology.

With these new appointments, the Bluetooth SIG board now consists of individuals from the following member companies; Apple, Bose, Cypress Semiconductor, Ericsson, Google, Intel, Lenovo, Microsoft, Nokia, Signify and Toshiba.

Bluetooth SIG | www.bluetooth.com

Cypress Semiconductor | www.cypress,com