December 2017: The Future of Microprocessors

Welcome to the December 2017 edition of the Embedded Artistry Newsletter!

This month I'd like to share my research on interesting innovations and research projects that will affect the future of microcontroller design and manufacturing.

The Future of Microprocessor Development and Manufacturing

In the past few months I've written to you about Intel's new FinFET transistor and "hyperscaling" chip design techniques and new DARPA electronic initiatives. I want to share my research on other innovations and programs that will affect microprocessor design and manufacturing.

Bespoke Processors

Most processors designed today are "general purpose" and meant to support a wide range of applications. By relying on general purpose processors, the manufacturing ecosystem can take advantage of economies of scale and enjoy reduced component costs. Even in situations where generic processors are too powerful for our specific application, it's cheaper to purchase an overpowered processor than it is to design an application-specific one.

Over-design is still costly, as unused features still have an impact on product size and power consumption. A research team at the University of Minnesota is investigating methods for identifying unused peripherals and logic gates in these generic processors. The team found that many of their test applications (e.g. FFT, autocorrelation, interpolation filtering) only used about 60% of the logic gates. They then created "bespoke" application-specific processors that removed completely unused circuitry. The resulting chip designs were on average 62% smaller and 50% lower-power than the starting openMSP430 microcontroller design. Since this effort is still early in its development, the solution is not yet cost-effective or manufacturable. However, it does allude to a future where we can create small, low-power, application-specific processors.

More on bespoke processors:

Embedded FPGAs

Field Programmable Gate Array (FPGA) technology allows for designers to describe a hardware/chip design using a programming language such as Verilog or VHDL. Traditionally FPGAs have been expensive, standalone components that are part of a hardware design. However, chip designers are increasingly making use of "embedded FPGAs" (eFPGA) in new microcontroller designs. In fact, you may already be using a chip with eFPGA technology without realizing it!

An embedded FPGA is an IP block that allows an FPGA to be integrated into a microcontroller design. Unlike standalone FPGA chips, eFPGAs rely on normal digital interconnects instead of supporting PHYs and I/O interfaces. eFPGA IP blocks provide the same benefits as standalone FPGAs (such as reprogrammability), but their tight coupling inside of the processor can result in higher communication speed and lower power consumption.

Embedded FPGAs provide a variety of chip design benefits:

  • Reduced impact of design changes - instead of expensive RTL changes, software can be updated
  • Reprogrammable and configurable I/O - allowing a single design to support a variety of I/O combinations (GPIO, UART, USART, I2C, I2S, SPI, etc.)
  • Offloading I/O processing from the MCU
  • Dramatically improved hardware accelerator performance (e.g. AES, SHA, FFT, JPEG encoding)
  • Creating reconfigurable hardware accelerators or implementing multiple accelerators using one mask
  • Maximizing battery life by implementing repetitive DSP/processor operations in a more efficient manner

While designers are primarily using eFPGAs to improve flexibility and reduce the impact of RTL changes, I look forward to a time when we will be able to program eFPGAs directly to maximize performance in our applications.

More on eFPGAs:

Embedded DARPA Initiatives

We covered two new DARPA efforts in October: 3DSoC, which is focused on creating design strategies for 3D circuit layouts; and FRANC, which seeks to overturn the Von Neumann architecture and create a new method for handling memory and logic operations. The other new DARPA initiatives are focused on improving the SoC design process to create a new era of innovation in electronics and application-specific designs:

  • Intelligent Design of Electronic Assets (IDEA) is focused on creating a design framework to enable non-experts to quickly design new complex electronics, including mixed-signal ICs, system-in-package modules, and PCBs
  • Posh Open Source Hardware (POSH) is focused on creating an open-source hardware design and verification framework to simplify SoC development
  • Software Defined Hardware (SDH) is exploring technology to create and improve reconfigurable software and hardware systems for use in data-intensive real-time processing applications, such as autonomous driving
  • Domain-Specific System on a Chip (DDSoC) is focused on creating a single platform to create and program SoCs for application-specific needs

More on the new DARPA initiatives:

Plastic Processors

Researchers at ARM and PragmatIC have been working on PlasticARM, a project focused on creating cheap, disposable micro-controllers printed on plastic. PlasticARM is based on the ARM Cortex-M0 32-bit SoC and currently uses a 2 micron process. The ARM team is also working with the University of Minnesota team to use the bespoke processor technique to reduce size and complexity of the resulting chips.

While not bleeding edge computationally, plastic chips will benefit from an estimated 90% lower IC cost than silicon chips. Plastic chips can also be flexible, thinner than a human hair, and have no rigid interconnection points. This could lead to interesting use cases, such as:

  • Disposable packaging displays
  • Sensors around water pipes to record average water pressure
  • Sensors around gas pipes to detect leaks
  • Sensors telling you whether your food is rancid or not
  • Pill bottle displays telling you whether you forgot to take your pills

More on plastic processors:

Lithographic Printing

Silicon chips are currently produced using the complex photolithographic printing process. Photoresist material is applied to a silicon wafer and spun at high speeds to produce a uniform layer. The photoresist is cured using UV light, and some of the photoresist is removed by a special solution. Afterward, a chemical etching process removes the uppermost substrate layer wherever the wafer is not protected by photoresist. This process is repeated to produce patterned layers of various materials that eventually result in a wafer of functional chips.

Molecular Imprints is a company working on utilizing imprint lithography (IL) to stamp out chips using a process similar to a printing press. Photoresist is applied to the silicon wafer using a method similar to inkjet printing. Then a glass stamp with the etching pattern is lowered onto the wafer, and the stamp draws the photoresist into its grooves via capillary action. Since the stamp is glass, the resist can be cured with UV light while the stamp is still on the wafer.

While there are still quality control problems to solve, the IL process is much simpler than photolithographic printing: simply spray photoresist, check alignment, stamp the wafer, and repeat. While Molecular Imprints is initially targeting hard drive production, I expect we will see printed processors soon enough.

More on Imprint Lithography:

Around the Web

Phil Koopman, of Better Embedded Software has made the course notes for his new embedded software college course publicly available. The course covers code quality, safety, and security. You can also find the course materials on the CMU course website.

Want to get started with ARM assembly? Check out this excellent 7-part series by Azeria Labs covering ARM assembly basics.

Embedded.com took a look at how embedded software development has evolved. Using surveys collected over the past twenty years, they explore evolutions in programming languages, processor usage, OS usage, and more.

Popular Articles

These were the most popular Embedded Artistry articles in November:

  1. Circular Buffers in C/C++
  2. Installing LLVM/Clang on OSX
  3. Implementing Malloc: First-fit Free List
  4. An Overview of C++ STL Containers
  5. std::string vs C-strings
  6. A GitHub Pull Request Template for Your Projects
  7. Creating and Enforcing a Code Formatting Standard with clang-format
  8. clang-format Wrapper Script Examples
  9. Implementing an Asynchronous Dispatch Queue
  10. A GitHub Issue Template for Your Projects

Thanks for Reading!

Have any feedback, suggestions, interesting articles, or resources to recommend to other developers? Respond to this email and let me know!

While you wait on the next edition, check out our website.

Happy hacking!

-Phillip

November 2017

Welcome to the November 2017 edition of the Embedded Artistry Newsletter! This is a monthly newsletter of curated and original content to help you build better embedded systems. This newsletter is intended to supplement the website and covers topics not mentioned there.

This month we'll be covering:

  • The recently announced vulnerability in the WPA2 algorithm
  • Industry standard APIs to make multi-core programming more accessible
  • The EMB² multicore programming framework
  • The recently announced ARM Platform Security Architecture
  • "The Coming Software Apocalypse"

WPA2 Vulnerability: Key Reinstallation Attacks

A serious flaw in the WPA2 security algorithm, which protects our Wifi networks, was announced this month. The attack vectors is dubbed KRACK for "Key Reinstallation Attack." The KRACK vector exploits a flaw in the WPA2 algorithm itself. Any correct implementation is likely to be affected. By exploiting the 4-away handshake protocol used to exchange encryption keys, a third-party can collect and replay the key installation message. This vulnerability enables packet replays, packet forgery, packet decryption, or man-in-the-middle attacks.

Stay alert and update your devices as soon as updates are available. Do not switch back to the less-secure WEP security protocol: once this flaw is patched, WPA2 will remain secure. If you are building or supporting a Wifi-enabled device, check with your chip or SDK vendors for updates and timelines.

More on the KRACK attack vector:


Industry Standard Multicore APIs

Multicore embedded systems are becoming increasingly popular. However, writing programs to use multicore processors effectively is a challenge. The Multicore Association (MCA) aims to improve the adoption of multicore programming by defining and promoting specifications that better enable multicore product development. If you are writing software destined for a multicore embedded system, consider using these APIs to keep your software portable and abstracted from underlying architectures.

The MCA currently defines three multicore APIs, covering task management (MTAPI), resource management (MRAPI), and communication and synchronization between cores (MCAPI).

The aim of the Multicore Task Management API (MTAPI) is to create a standardized API for task-parallel programming on a wide range of hardware architectures. Manually creating and managing threads can be complex, error-prone, and depends on your operating system and hardware. MTAPI abstracts hardware and operating system details and allows programmers to focus on the parallel programming solution. There are no compiler, hardware, or operating system dependencies, and the API is written in C to minimize ABI interoperability problems. The API can be implemented on resource-limited devices and covers a variety of multicore architectures and hardware acceleration units. Task scheduling can be optimized for latency and fairness, enabling its use on systems with soft real-time requirements.

The Multicore Resource Management API (MRAPI) specifies application-level resource management capabilities. This API allows multicore applications to coordinate concurrent access to various system resources.

The Multicore Communications API (MCAPI) defines an API and semantics for communicating and synchronizing processing cores in embedded systems. MCAPI is a message-passing API that is designed for closely-distributed systems (e.g. multiple cores on a single chip, multiple chips on a single board). The API is kept simple to support sufficient functionality while allowing efficient implementations for resource constrained systems.

More information on the MCA standards:


Multicore Framework: Embedded Multicore Building Blocks

Embedded Multicore Building Blocks (EMB²) is an open-source C/C++ library for developing parallel embedded systems applications. EMB² is built on the Multicore Task Management API that we reviewed in the previous section.

EMB² provides generic building blocks for building parallel embedded applications, including basic parallel algorithms, concurrent data structures, and application skeletons. The majority of the framework APIs are non-blocking, avoiding common multi-threaded problems encountered when using locks.The framework utilizes an abstraction layer that makes it easily ported to new operating systems and processor architectures.

EMB² is implemented as a C API with C++ wrappers. The project is based on C99 and C++03 to provide maximum usability in the embedded world. C11 and C++11 can be selected for use of the standard atomic operations instead of the EMB² atomics.

My favorite aspect about this project is the emphasis on quality: the project maintains zero compiler warnings, sports 90% unit test coverage, utilizes static analysis and automated rule checks, and has formally validated pieces of the system. It's refreshing to find a team that cares about quality!

If you're looking for a simple framework to get started with multicore embedded development, check out EMB²:


The ARM Platform Security Architecture

As the news frequently highlights, inadequate security implementations on embedded systems is a major problem. Last September, ARM announced their intentions to work on a platform security architecture to help combat this threat. based on announcements this month, it looks like ARM is delivering on their promise.

Dubbed the Platform Security Architecture (PSA), ARM is focusing on three major components:

  1. Threat Models and Security Analyses derived from a range of typical IoT use cases
  2. Architecture specifications for firmware and hardware
  3. An open source project similar to Arm Trusted Firmware

The PSA is targeted for smaller cores and low-cost devices. Sensitive assets, such as keys and credentials, will be managed by a Secure Processing Environment (SPE) and will be separated from the application firmware.

In addition to the PSA, ARM has announced two new security-related cores. The CryptoIsland-300 is a programmable security core which expands upon the CryptoCell that they announced last year. The SDC-600 is a secure debugging channel that will allow users to enable or disable debugging abilities by using a cryptographic certificate.

The PSA is initially targeted for Cortex-M devices and will include open-source implementation examples. The PSA release is expected in Q1 of 2018. Support for Cortex-R and Cortex-A devices will follow after Cortex-M.

More on the ARM PSA:


The Coming Software Apocalypse

The Atlantic recently published an article titled "The Coming Software Apocalypse". Our world is becoming increasingly digitized and we are encountering more and more flaws in the software we depend on. Even our cars, which were primarily mechanical systems once upon a time, are now comprised of 100 million lines of code. The article dives into some of the challenges involved with the increase in software complexity, primarily focusing on limitations in our intellectual management of large software project. Following this premise, the author advocates increased emphasis on using tools during the development process. Software should be modeled before any code is written, algorithms should be checked with formal methods or tools such as TLA+, and code generators should be used to reduce programmer errors.

I later stumbled across a response to The Atlantic's article titled "Tools are not the Answer". The author of this post emphasizes a point which I wholeheartedly agree with: tools are helpful, but not the complete answer. Programmers must hold themselves to higher standards.

The rebuttal emphasizes that our software woes primarily stem from two causes:

  1. Too many programmers take sloppy short-cuts under schedule pressure.
  2. Too many other programmers think it’s fine, and provide cover.

And the obvious solution:

  1. Raise the level of software discipline and professionalism.
  2. Never make excuses for sloppy work.

This is not to say that tools won't help: our software is still becoming increasingly complex and difficult to manage. We must improve our development processes and hold ourselves to higher standards.

Read more here:


Selected Quotes from the Articles

“Typically the main problem with software coding—and I’m a coder myself,” Bantégnie says, “is not the skills of the coders. The people know how to code. The problem is what to code. Because most of the requirements are kind of natural language, ambiguous, and a requirement is never extremely precise, it’s often understood differently by the guy who’s supposed to code.”

This is the trouble with making things out of code, as opposed to something physical. “The complexity,” as Leveson puts it, “is invisible to the eye.”

The software did exactly what it was told to do. The reason it failed is that it was told to do the wrong thing.

Take error handling and correction seriously in your designs:

But, as described in a report to the FCC, “the situation occurred at a point in the application logic that was not designed to perform any automated corrective actions.”

We already know how to make complex software reliable, but in so many places, we’re choosing not to. Why?

I stood before a sea of programmers a few days ago. I asked them the question I always ask: “How many of you write unit tests on a regular basis?” > Not one in twenty raised their hands.


Website Updates

I added additional C++ references to the Software References page. I also expanded the Glossary with additional terms and an improved organizational scheme.

These were the most popular articles in October:

  1. Circular Buffers in C/C++
  2. Installing LLVM/Clang on OSX
  3. Implementing Malloc: First-fit Free List
  4. std::string vs C-strings
  5. An Overview of C++ STL Containers

Thanks for Reading!

Have any feedback, suggestions, interesting articles, or resources to recommend to other developers? Respond to this email and let me know!

Happy hacking!

-Phillip

October 2017

Welcome to the October 2017 edition of the Embedded Artistry Newsletter! This is a monthly newsletter of curated and original content to help you build better embedded systems. This newsletter is intended to supplement the website and covers topics not mentioned there.

This month we'll be covering:

  • The BlueBorne Bluetooth vulnerability
  • DARPA funds embedded initiatives
  • A helpful introductory RTOS series
  • Amazon launches an FPGA cloud
  • A terrible security flaw discovered in pacemakers
  • Limiting the number of characters printf displays

The BlueBorne Bluetooth Vulnerability

Armis Labs recently announced a series of eight attack vectors that endanger the majority of our Bluetooth devices, including Android, iOS (pre-10.0), Windows, and Linux. The threat is dubbed "BlueBorne", a blend between Bluetooth and airborne. Affected devices are vulnerable to BlueBorne as long as Bluetooth is enabled, even if the device is not discoverable and not paired to the attacker's device. BlueBorne does not require any action to be completed by the user, and the user may never know his device has been compromised. The disclosed vulnerabilities are fully operational and enable a variety of attacks, such as arbitrary code execution, man-in-the-middle, and information leakage.

Bluetooth is a nearly ubiquitous technology and Armis estimates that over 8.2 billion devices may already be affected. Popular libraries like BlueZ which is used on a variety of PC and embedded systems are compromised. It is recommended to turn off Bluetooth when you are not using it until the vulnerabilities have been addressed. Ensure your software is up-to-date and keep an eye out for software updates on your Bluetooth-enabled systems. If you are building a Bluetooth-enabled system, review the technical paper and ensure that your design is not suspect to the disclosed vulnerabilities.

For more on BlueBorne:

DARPA Funds Embedded Initiatives

DARPA has announced that it is providing funding for six new programs with an embedded focus. DARPA is focusing the new initiatives on researching new materials and integration techniques, improving circuit design tools, and creating new system architectures for microelectronics. The programs that sound the most exciting are in the Materials and Integration category: "Three-dimensional Monolithic System-on-a-chip" (3DSoC) and "Foundations Required for Novel Compute" (FRANC).

3DSoC is aimed at improving speeds and reducing power consumption by transitioning from a 2D circuit layout to a 3D circuit layout. By constructing microelectronic circuits in 3D space (e.g. in a cube) we can create novel design strategies and arrangements for our circuits and chips. Migrating to a 3D circuit arrangement is expected to improve logic density, increase computational speed, optimize for size, and reduce power.

FRANC is looking to overturn John von Neumann's computer architecture model which separates the memory and processing blocks. Computations are often limited by the speed at which data can be moved back-and-forth between the processor and memory. As a result, memory transfer speeds are a major bottleneck in many systems. FRANC's aim is to address this bottleneck by developing a new method for handling memory and logic in a combined manner.

It's exciting to see DARPA inducing major changes in our microelectronic circuits and system architectures. Innovations like these will have a significant impact on our industry in the coming decades.

More on DARPA's new initiatives:

An Introductory RTOS Series

The embedded guru Colin Walls has been working on a series called RTOS Revealed. This series of articles is a great way to learn more about real-time and OS concepts, multi-threaded scheduling, and how to use an RTOS. Colin covers basic RTOS concepts and dives into the Nucleus SE RTOS to provide concrete examples. I recommend reviewing the entire series if you are new to the embedded systems space.

Here's the current lineup of articles:

New articles in the series are released on a monthly cadence.

Amazon Launches an FPGA Cloud

Xilinx and Amazon have partnered to launch customizable FPGA instances in the AWS Cloud for applications that can benefit from hardware acceleration. These instances are built on the Xilinx Virtex UltraScale+ FPGAs and can include up to eight FPGAs per instance. Amazon also provides an FPGA Hardware Developer Kit (HDK) to simplify development of FPGA instances.

A Terrible Flaw Discovered in Pacemakers

465,000 U.S. patients have been told to visit a clinic to receive a firmware update for their St. Jude pacemakers. The firmware contains a security flaw which allows hackers within radio range to take control of a pacemaker. This is one more example demonstrating that security must be a crucial aspect of embedded systems design and development. Taking security shortcuts never pays.

Limiting the Number of Characters printf Displays

I originally hesitated about sharing this tip, but I've found myself repeatedly it: You can control how many characters printf spits out for the %s symbol by specifying a precision.

There are two options for controlling the length. You can specify the maximum using a fixed value:

// Fixed precision in the format string
const char * mystr = "This string is definitely longer than what we want to print.";
printf("Here are first 5 chars only: %.5s\n", mystr);

You can also control the length programmatically by using an asterisk (*) in the format string instead of the length. The length is then specified as an argument and is placed ahead of the string you want to print.

// Only 5 characters printed. When using %.*s, add an argument to specify the length before your string
printf("Here are the first 5 characters: %.*s\n", 5, mystr);

Website Updates

This month, the website went through a total visual redesign!

Old pages such as "Around the Web" have been split out into separate pages to provide better categorization:

I've also added some new pages in the "About" section:

These were the most popular articles in September:

  1. Installing Clang/LLVM on OSX
  2. Circular Buffers in C/C++
  3. C++11 Fixed Point Arithmetic Library
  4. An Overview of C++ STL Containers
  5. std::string vs C-strings

Goodbye to a Dear Friend

We lost our dear companion and beloved mascot Jensen to stomach cancer. She will be sorely missed.

IMG_7389.jpg

Thanks for Reading!

Have any feedback, suggestions, interesting articles, or resources to recommend to other developers? Respond to this email and let me know!

September 2017

Welcome to the September 2017 edition of the Embedded Artistry Newsletter! This is a monthly newsletter of curated and original content to help you build better embedded systems. This newsletter is intended to supplement the website and covers topics not mentioned there.

This month we'll be covering:

  • Follow-up Bluetooth Mesh reading recommendations
  • A flexible 2.4GHz antenna suitable for metal surfaces
  • A selection of 2017 embedded market reports that are worth reviewing
  • The incredible engineering behind the Voyager spacecraft
  • How Intel's chip design advances have allowed them to keep Moore's Law alive
  • Building your own SMT reflow oven using a halogen lamp

Bluetooth Mesh Articles

In last month's newsletter, we reviewed two major additions to Bluetooth: Bluetooth 5 and Bluetooth Mesh. Since Bluetooth Mesh is fresh off the press, the Bluetooth SIG has been published some great articles to demystify the new standard.

Check out these recent posts:

A Flexible 2.4GHz Antenna for Metal Surfaces

I was surprised to see an announcement this month regarding an antenna designed for metal surfaces. Building connected devices can be quite a challenging experience. You need to give careful attention to antenna placement and tuning in order to optimize your product's performance. These challenges increase significantly if your product has integrated metal. Metal surfaces can wreak havoc on your antenna design, resulting in antenna detuning, efficiency losses, and reduced communication ranges.

Laird's new mFlexPIFA antenna looks like a promising solution for products with metal enclosures. The mFlexPIFA is about the size of a quarter and is built for 2.4GHz devices. The antenna is adhesive-backed and can be mounted directly onto metal surfaces without detuning the antenna. The design is also flexible, allowing you to mount your antenna to curved surfaces.

Consider this antenna solution in your next connected design, especially if it involves a metal enclosure

More on the FlexPIFA antenna:

2017 Embedded Systems Market Studies & Surveys

"Embedded systems" is a blanket term describing a vast array of devices with differing purposes, computational capabilities, and reliability levels. It's easy to forget the differences in embedded applications and devices, and I find that reviewing market surveys provides some great insight into how the field is developing. I want to share three market surveys with you today:

The Hax hardware accelerator's embedded market study focuses on general trends in hardware development, development directions in different sectors (e.g. consumer, health, industry), automation (which has taken off in China), and hardware funding models.

The AspenCore market survey is less focused on where the market is heading. Instead it dives into areas such as development practices, tools, project timelines, and processor selection.

The Barr Group's embedded systems safety and security survey provides some interesting and alarming insights. They conclude that even though there is increased risk of bodily injury, many automotive design teams are still not using best practices such as static analysis, regression testing, coding standards, and code reviews.

In reading these surveys, I noticed the following general trends:

  • C is still dominating in the embedded space
  • More and more projects are using multiple processors
  • Industrial sensing and automation is rising
  • Devices are becoming increasingly "connected"
  • In many cases best practices are being overlooked

The Voyager Mission Celebration Series

All About Circuits has been celebrating the 40th anniversary of the Voyager I and II spacecraft by dedicating a series of articles to them. The articles dive into the electronics and engineering behind these incredible systems. I have an intense level of respect for the engineers who built such reliable systems without the bountiful computational and technological capabilities that we have today. It would be amazing if any of my devices are still operating 40 years from now, even on the comfortable confines of Earth!

Ten excellent articles have been published in the Voyager spacecraft series:

  1. Voyager Mission Anniversary Celebration Series: Introduction
  2. Powering the Voyager Spacecraft with Radiation: The RTG (Radioisotope Thermoelectric Generator)
  3. Communicating Over Billions of Miles: Long Distance Communications in the Voyager Spacecraft
  4. The Brains of the Voyager Spacecraft: Command, Data, and Attitude Control Computers
  5. Exploring the Solar System with the Voyager Spacecraft’s Cameras, Polarimeters, and Magnetometers
  6. The Infrared Interferometer, Spectrometer, and Radio Astronomy of the Voyager Spacecraft
  7. How the Voyager Missions’ Plasma Science Investigations Teach Us About Solar Winds
  8. The Low Energy Particle Instruments on the Voyager Spacecraft
  9. The Voyager Mission: Insight into Our Solar System
  10. Voyager Anniversary Celebration: 40 Years in Space

The New York Times has recently published "The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe" which takes a look at the human side of the Voyager missions.

While not part of the Voyager series, there was another recent article describing how the space race gave us GPS. If you're interested in the history and theory behind GPS, take a look at "How the Space Race Gave Us GPS Technology".

Intel's New Processor Designs Keeping Moore's Law Alive

This article was published earlier in the year, but I still think its an illuminating read. Back in 2002, Intel announced a breakthrough with their new field effect transistor ("FinFET") design, dubbed the "tri-gate transistor". In 2011, Intel finally announced their first chips built with tri-gate transistors and that the new transistor was the official future of Intel's processing lines. The 2011 announcement involved a 22nm process, and Intel followed that up in 2014 with a 14nm process. Intel is continuing to maintain their 14nm process and finally coming out with a 10nm process this year.

At a time when keeping up with Moore's Law seems like an impossible task, Intel has managed to keep the law alive: both their 14nm and 10nm processes have more than doubled in transistor density. Intel credits their "hyperscaling" techniques, such as reducing the number of dummy gates required to isolate logic cells and stacking metal contacts above gates. These hyperscaling techniques give Intel a transistor density advantage over their competitors at the same process size. For example, Samsung's 10nm process is comparable in transistor density to Intel's 14nm process.

While I don't think I'll be writing firmware for Intel-powered embedded devices in the near future, I'm excited to see the pressure that Intel's 10nm process puts on other chipmakers. Size is a major concern in the embedded world, so I'm certain we will see some of these hyperscaling techniques applied to other chip families in the future.

More on Intel's new architecture, Transistors, and Moore's Law:

Build Your Own SMT Reflow Oven With a Halogen Lamp

I've been slowly building an electronics lab over the years, and I'm lucky enough to possess an oscilloscope, a bench-top DMM, and a logic analyzer. One project I've had in mind is building an SMT reflow oven. Being able to reflow boards would increase assembly and repair capabilities. I was thrilled to find a blog post about building an SMT reflow oven using a halogen lamp. The author was able to build his own SMT reflow oven for ~$30 by using a halogen lamp, an AC dimmer, and a reflow oven controller.

I discovered the SMT reflow project through Dangerous Prototypes. Check out their website if you're looking for electronics projects to tackle in the future.

Website Updates

I've made a few updates to the website:

  • Updated the Development Kits page to have a much nicer presentation style. Each development kit has its own dedicated blog post, allowing me to provide more detailed information for each kit.
  • Added more terms to the Glossary

These were the most popular articles over the past month:

  1. An Overview of C++ STL Containers
  2. Installing LLVM/Clang on OSX
  3. Choosing the Right STL Container: General Rules of Thumb
  4. C++11 Fixed Point Arithmetic Library
  5. Circular Buffers in C/C++

Happy hacking!

-Phillip

August 2017: Bluetooth Edition

Welcome to the August 2017 edition of the Embedded Artistry Newsletter! This is a monthly newsletter of curated and original content to help you build better embedded systems. This newsletter is intended to supplement the website.

This month we'll be covering:

  • MAX17055 - a new fuel gauge chip from Maxim
  • The Bluetooth 5 standard and changes to the PHY
  • Processors and development kits that support Bluetooth 5
  • The new Bluetooth Mesh standard
  • SDKs that support Bluetooth Mesh
  • A handy trick for when you can't read the part numbers on a chip

MAX17055 - New Maxim Fuel Gauge

Those of us who have used TI's GasGauge line understand how frustrating their parts can be. Undocumented behavior in the gauge firmware, required battery characterization, and per-product configuration can lead to frustrating bugs that are hard to debug. Unless you're a large customer, you have very little chance of getting help from TI and problems often stay unresolved.

One of my clients is using a new fuel gauge chip - the MAX17055 Fuel Gauge. Maxim claims that their gauge "eliminates battery characterization requirements and simplifies the host software interaction" and requires only 7µA of operating current. Unlike TI, Maxim provided great direct support for integrating this part into the new system.

Maxim provides a software implementation guide which describes various methods of using the part. By following the software guide, I implemented a driver for my system in less than an hour. Once the new boards arrived, the driver was working perfectly in a matter of minutes and the initial calibration resulted in readings that were within 5% of the actual voltage value. Since the Maxim Fuel Gauge is a learning gauge, this initial accuracy should improve over a few charge/discharge cycles.

If you're looking for a fuel gauge to use in your next battery-powered device, I recommend the MAX17055.


Bluetooth 5 & Bluetooth Mesh

We've seen two major Bluetooth specification releases in the past 12 months: Bluetooth 5 and Bluetooth Mesh.

It typically takes ~6 months for us to see devices once a new specification is released. We're well into that window for Bluetooth 5, so expect to start seeing new devices soon. Bluetooth Mesh is fresh off the press, so now is the time to start familiarizing yourself with the specification to stay ahead of the curve.

Next, I'll describe the changes involved with the Bluetooth 5 and Bluetooth Mesh specifications. I'll also provide some supplementary reading material and showcase some interesting Bluetooth 5 chips and development kits.


Bluetooth 5

The Bluetooth 5 specification was released in December 2016. The new specification claims a variety of improvements:

  • 4x range
  • 2.5x lower power (BLE)
  • 2x speed (supporting a new 2Mbit/s high-throughput mode)
  • Increased advertising data payload from 31B to 255B
  • Ability to chain advertising packets to create extended payloads
  • Improved coexistence with other WiFi, Bluetooth, and 2.4GHz devices via an improved channel hopping algorithm

The speed and range improvements are brought about by changing the physical layer (PHY) of the Bluetooth protocol stack. The Bluetooth PHY now supports two additional modes, which allow for increased speed or increased range. The three Bluetooth PHYs are:

  1. "LE 1M" - the PHY used in Bluetooth 4
  2. "LE 2M" - the 2Mb/s PHY, which doubles the speed of the LE1M PHY
  3. "LE Coded" - the new long-range PHY that adds error correction

The increased range does not involve any transmit power increases. Instead, the increase is provided by improving receiver sensitivity and utilizing Forward Error Correction (FEC). FEC adds redundant data bits to the transmitted packets. These redundant bits allow for error correction to be performed by the receiver and for messages to be correctly decoded at a lower signal-to-noise ratio (SNR). This provides a ~12dB improvement in receiver sensitivity, resulting in the 4x range improvement. Of course, the redundant information does come with a penalty in reduced data throughput due to the need to transmit redundant bits.

You can switch between PHYs by using the new HCI command "LE Set PHY". You can independently select the PHY to use for both transmit (TX) and receive (RX). This means that we can switch between PHY modes depending on our operational situation. Additional HCI commands are defined to support setting the default PHY and for querying the PHY capabilities of remote devices.

Bluetooth 5 is operationally compatible with Bluetooth 4.x devices. However, the changes to the Bluetooth 5 specification have been made at the PHY layer. You will be tied to the LE 1M PHY and will not be able to take advantage of Bluetooth 5 benefits.

For more details on Bluetooth 5, read these:

Bluetooth 5 Chips & Development Kits

Let’s take a look at some development kits and chips from Nordic and Silicon Labs that already support the new standard.

Nordic nRF52

Nordic offers Bluetooth 5 support in its nRF52 line, consisting of three chips: nRF52810, nRF52832, and nRF52840. All of the nRF52 chips support the new CSA algorithm, the LE 2M PHY, and increased advertising packet size. However, only the nRF52840 has support for the new long-range LE Coded PHY.

nRF52810 & nRF52 DK

The nRF52810 is the simplest of the three Bluetooth 5 chips, sporting a Cortex-M4 and a basic set of peripherals. Due to the reduced flash, RAM, and peripheral counts, this chip is useful as a dedicated Bluetooth processor in a multi-chip system.

The nRF52810 itself is not included on a development kit. Nordic recommends the nRF52 DK for exploring the low-end of the nRF52 series. This starter board is compatible with Arduino shields, allowing for some interesting prototyping options. The nRF52 DK utilizes a nRF52832, so you'll want to hold off on using unsupported features if you're going to uses the nRF52810.

nRF52810 Specifications:

  • 32-bit Cortex-M4 64MHz Processor
  • 1.7v to 3.6v operation
  • 192kB flash + 24kB RAM
  • Up to +4dBm output power
  • -96dBm sensitivity, Bluetooth low energy
  • 1 x Master/Slave SPI
  • 1 x Two-wire interface (I²C)
  • 1 x PWM (4 channels)
  • AES HW encryption
  • 8-channel 10/12-bit ADC
  • Quadrature decoder
  • 64-level analog comparator
  • Real Time Counter (RTC)
  • Digital microphone interface (PDM)

More on the nRF52810:

Nordic nRF52832 & Nordic Thingy:52

The nRF52832 is the mid-tier Bluetooth 5 chip. The nRF52832 is built on a Cortex-M4F processor. The nRF52832 provides a significant increase in flash, RAM, and peripherals over the nRF52810. These improvements make the nRF52832 an attractive choice as a primary processor for your system or for exploring new BLE features like IPv6 support. The nRF52832 includes an on-chip NFC tag to support out-of-band pairing. You can utilize the NFC pairing method for a simpler process of exchanging authentication information between two bluetooth devices.

The nRF52 DK supports the nRF52832, but Nordic also sells the Thingy:52 development kit. The Thingy:52 provides you with a variety of environmental sensors (temp, humidity, pressure, air quality, color, and light), a 9-axis IMU (accelerometer, gyro, and compass), a speaker, and a microphone. The range of components provided with this dev kit is impressive and useful for many Bluetooth prototyping scenarios. Nordic also supplies a Thingy:52 app and demo code to get you up and running as quickly as possible.

nRF52832 Specifications:

  • 32-bit ARM Cortex-M4F 64MHz Processor
  • 1.7v to 3.6v operation
  • 512kB flash + 64kB RAM
  • On-chip NFC tag for Out-of-Band (OOB) pairing
  • Up to +4dBm output power
  • -96dBm sensitivity, Bluetooth low energy
  • 3 x Master/Slave SPI
  • 2 x Two-wire interface (I²C)
  • UART (RTS/CTS)
  • 3 x PWM
  • AES HW encryption
  • 12-bit ADC
  • Real Time Counter (RTC)
  • Digital microphone interface (PDM)
  • On-chip balun

More on nRF52832:

nRF52840 & Preview DK

The nRF52840 is the king of the Bluetooth 5 chips and the only chip in the product line that supports 802.15.4 and the new Bluetooth 5 LE Coded PHY. The nRF52840 provides an impressive 1MB of flash and 256kB of RAM.The chip sports additional peripherals, such as the ARM Cryptocell cryptographic co-processor and a USB 2.0 controller. With an improved output power of up to +8dBm, the nRF52840 is definitely the chip to pick if you're looking at long-range Bluetooth communications.

Nordic has released a nRF52840 Preview Development Kit (PDK). This kit is more similar to the nRF52 DK than the Thingy:52. The PDK provides no external peripherals or sensors to play with, but like the nRF52 DK it is compatible with Arduino shields for easy prototyping.

nRF52840 Specifications:

  • 32-bit ARM Cortex-M4F 64MHz Processor
  • 1.7v to 5.5v operation
  • 1MB flash + 256kB RAM
  • Up to +8dBm output power
  • 802.15.4 radio support (ZigBee and Thread)
  • On-chip NFC
  • PPI –Programmable Peripheral Interconnect
  • 48 x GPIO
  • 1 x QSPI
  • 4 x Master/Slave SPI
  • 2 x Two-wire interface (I²C)
  • I²S interface
  • 2 x UART
  • 4 x PWM
  • USB 2.0 controller
  • ARM TrustZone CryptoCell-310 Cryptographic and security module
  • AES 128-bit ECB/CCM/AAR hardware accelerator
  • Digital microphone interface (PDM)
  • Quadrature decoder
  • 12-bit ADC
  • Low power comparator
  • On-chip balun

More on nRF52840:

Silicon Labs EFR32

Silicon Labs offers Bluetooth 5 support in the EFR32 Blue Gecko line of SoCs. Similar to the Nordic nRF52810, the EFR32 series is built upon a Cortex-M4 processor. The EFR32 line sports a whopping +19dBm of programmable output power in their beefiest configuration.

Silicon Labs provides a Blue Gecko Starter Kit to support EFR32 development. The starter kit is modularized to support a wide variety of radio daughter boards for easy prototyping and chip comparisons. The starter kit comes with two Bluetooth radio daughter boards. Only the provided EFR32BG13 radio board supports the LE Coded and LE 2M PHYs. The starter kit contains a few push buttons and a coin cell battery holder, but does not include other on-board peripherals. A wide variety of headers are supplied for your prototyping needs.

Unlike Nordic's nRF52 line, the EFR32 line has many different chip configurations. Also, not all EFR32 chips support the new 2M PHY and LE Coded PHY, so be sure to include those features in your search. Silicon Labs provides a full list of EFR32 SoCs, so you can find one that fits your needs exactly.

Sample EFR32 Specifications using maximum values:

  • ARM Cortex-M4 Processor (up to 40MHz)
  • Up to 1MB of flash
  • Up to 256kB SRAM
  • Up to +19dBm output power
  • AES256/128 hardware accelerator
  • 12-bit ADC
  • Current DAC (4-bit)
  • Up to 4x analog comparators
  • Low-energy UART
  • Up to 4x USART (SPI, UART, I2S, IrDA)
  • Up to 2x I2C
  • Up to 65 GPIOs
  • On-chip balun

EFR32BG12P632F512FM38 Specifications (Blue Gecko Starter Kit):

  • ARM Cortex-M4 40 MHz Processor
  • 512kB Flash + 64kB SRAM
  • +10dBm output power
  • -103.3dBm receiver sensitivity
  • AES-128/256 hardware accelerator
  • 12-bit ADC
  • Current DAC (4-bit)
  • Up to 4x analog comparators
  • 4x UART Ports
  • 3x USART ports (SPI, UART, I2C)
  • 2x I2C ports
  • 31 GPIOs

More on EFR32:


Bluetooth Mesh

Bluetooth Mesh is not included in the Bluetooth 5 standard. It was released in July 2017. Bluetooth Mesh provides the ability for Bluetooth devices to implement a many-to-many (m:m) network with a maximum size of 32,000 devices. Previously we were limited to a one-to-many (1:m) topology, where a central Bluetooth hub was responsible for broadcasting messages to the various nodes. In addition to m:m topology support, Mesh allows devices to relay data to other devices that are not in direct radio range. This re-broadcasting scheme allows the network to cover a larger area than with Bluetooth LE. Since Bluetooth Mesh is built upon Bluetooth LE, it can be utilized by both Bluetooth 4.x and Bluetooth 5 devices. Existing devices in the field can take advantage of Bluetooth Mesh as long as they are capable of firmware updates.

Bluetooth Mesh devices communicate using a publish/subscribe messaging system. Whenever a device publishes a message to a specific topic, all devices who are subscribed to that topic will receive a copy. Mesh also introduces the concept of device "state" which can be adjusted through published messages. The new "model" concept defines a mesh node's messages, states, and behavior.

Bluetooth Mesh utilizes a "managed flooding" approach, allowing for a peer-to-peer multi-path communication network. Since there is no central hub or routing nodes, the network is more resilient to device failures. Messages are retransmitted by devices which are designated as "relays", allowing messages to reach nodes that are not in direct radio range. A message can make a maximum of 127 hops, allowing us to cover quite a large physical area. Devices contain a message cache which is used to determine whether a particular message has been seen before. If it has, the message is discarded and not processed by the stack.

Some of our mesh nodes are likely to be low-power devices which wake up periodically to relay data. Bluetooth Mesh allows us to designate "friend" nodes which are not power constrained. These friend nodes store messages intended for the low-power node. Once the low-power node wakes up, it can request the cached information from its friend. This concept of "friendship" allows us to implement an efficient wakeup schedule to conserve battery life.

Mesh nodes send out regular heartbeat messages to let us know that they are alive. These heartbeat messages allow the network to learn about its topology and help devices avoid unnecessary message retransmissions. There is also a mandatory "health" model which allows devices to send out fault information, such as in low battery or overheating conditions.

Bluetooth SIG is targeting industrial applications so Bluetooth Mesh is designed with security in mind. Every packet is encrypted and authenticated, asymmetric cryptography can be utilized, and security keys get refreshed periodically.

It's possible to utilize multiple mesh networks in the same location. Each mesh network has an identifier which indicates which network the packet belongs to. Also, thanks to the built-in security, devices cannot decrypt or authenticate mesh packets from another mesh network. Each network remains isolated from the other.

Large-scale sensor networks, asset tracking, building automation, and commercial lighting solutions are expected to be the first use cases of the new mesh networking protocol. Multiple projects that I've worked on recently will benefit from switching to Bluetooth Mesh.

More on Bluetooth Mesh:


Bluetooth Mesh SDKs

In order to build a mesh network, we need a compatible software stack. Bluetooth mesh networks require a Bluetooth LE 4.x or 5.0 which supports GAP Broadcaster and Observer roles. These roles are used to advertise and scan for advertising packets. Luckily, both Nordic and Silicon Labs have made our lives easy and provide full-fledge SDKs to support Bluetooth Mesh development.

Nordic

Nordic supplies an nRF5 SDK for Mesh. The SDK is currently noted as "alpha" quality, but you can download the SDK and start prototyping immediately.

The Mesh SDK is compatible with both the nRF51 and nRF52 processor lines. The SDK comes with example applications and models for beaconing, lighting control, and provisioning devices (including provisioning through relay nodes). The SDK allows for node-to-node and node-to-group communications and supports configurable scanning and advertising interval. It's also worth noting Nordic's excellent OTA DFU support remains in place with the Bluetooth Mesh SDK.

More on the Nordic Mesh SDK:

Silicon Labs

Silicon Labs also supplies a Bluetooth Mesh SDK. The SDK is currently noted as "beta" quality. You must create an account and request access to the SDK before you are able to download it. Silicon Labs is lighter on the describing support currently provided in their SDK, but they claim to be compliant with the existing specification and support the LE 2M and LE Coded PHYs. My SDK access request was approved within 24 hours.

More on Silicon Labs Mesh SDK:


Can't See IC Part Numbers? Try this

I learned an awesome trick from EDN's recent article "Simple Trick Lets You See Your Parts". If you need to read the part number on an IC but can't make out the details, simply apply a clear piece of cellophane tape to the part. I've used this trick multiple times in the past week, and it's extremely helpful when I'm away from a microscope.

EDN provides a great warning that you should heed:

Be careful though, as tape can generate considerable ESD, so avoid touching the actual pins of the package.

ReadingICPartNumbers

Website Updates

I've made a few updates to the website:

  • Created a new Development Kits page. Take a look if you need inspiration for your next project or want to experiment with more complex systems.
  • Added clang and Modern C++ references to Around the Web
  • Added language recommendations to Getting Started. I also removed an outdated C++ Idioms reference and added a book recommendation for developing your software career.
  • Expanded the Glossary

These were the most popular articles over the past month:

  1. Ditch Those Built-in Arrays for C++ Containers
  2. Migrating from C to C++: Take Advantage of RAII/SBRM
  3. Using A C++ Object's Member Function with C-style Callbacks
  4. Ditch Your C-style Pointers for Smart Pointers
  5. Installing LLVM/Clang on OSX

July 2017: First Edition!

Welcome to the first edition of the Embedded Artistry Newsletter! It’s a monthly newsletter of curated and original content to help you build better embedded systems. This newsletter is intended to supplement the website and covers topics not mentioned there.

This month we’ll be covering:

  • One of the best books I’ve found on debugging
  • A great introductory embedded programming book
  • cmocka, a C unit testing framework
  • Particle Development Kits
  • Nordic nRF5x SoCs
  • Marvell MW300 SoC
  • MAX17055 Fuel Gauge
  • Shenzhen in the 1980s: Any guesses?
  • Articles I recommend reading