Author Archives: Majeed Ahmad

About Majeed Ahmad

Majeed Ahmad is former Editor-in-Chief of EE Times Asia, a sister publication of EE Times. At Global Sources, a Hong Kong-based publishing house, he also headed the content operations of electronic titles, including magazines relating to electronic components, consumer electronics, computer, security and telecom products. Majeed has been a technology and trade journalist for more than 15 years.

The smart router is ready for IoT play


The evolution of router has reached the IoT’s doorsteps, and it raises some interesting prospects for industrial and smart home markets.


The router used to be largely a dumb device. Not anymore in the Internet of Things arena where node intelligence is imperative to make a play of the sheer amount of data acquired from sensors, machines and other ‘things.’ The IoT router marks a new era of network intelligence — but what makes a router smart?

owtbrd.png

For starters, it employs embedded hardware platforms with DIY capabilities while balancing the performance and power consumption requirements. Next, an IoT router provides the operational status on an LCD screen while manipulating the data from different interfaces. In human machine interface (HMI) applications, for example, a smart router offers LCD and touch screen interfaces on expansion I/Os.

Take the case of the DAB-OWRT-53 smart router, which is developed by the Belgian design house DAB-Embedded. The sub-100 euro device — based on Atmel’s SAMA5D36 processor and OpenWRT router hardware platform — is mainly targeted at smart home and industrial IoT applications.

The smart router of DAB-Embedded

The IoT router supports popular wireless interfaces such as Wi-Fi, ZigBee and Z-Wave, as well as a diverse number of wired interfaces including Ethernet, USB, CAN 2.0A/B, KNX and RS-232. And all the data from these interfaces can be stored in either microSD card or NAND flash.

Anatomy of Smart Router

The Atmel | SMART SAMA5D36 is at the heart of the smart router design. First and foremost, it optimizes power consumption in the battery-operated router that features 3.7V lithium polymer battery support with charging capability over a microUSB connector. The router boasts eight hours of battery lifetime while being in full ON mode with Wi-Fi communications.

Second, the ARM Cortex-A5 processor shows a robust performance in the communications domain. For instance, the SAMA5D36 implements routing functionality to transfer data from one Ethernet port to another in a way that router designers don’t require an external hardware hub or switch. Moreover, Atmel’s MPU offers greater flexibility to run a lot of embedded software packages such as OpenZWave and LinuxMCE.

Third, the SAMA5D36-based IoT router offers users the ability to manipulate firewall settings, Disable PING, Telnet, SSH and UPnP features. Furthermore, the hardware security block in SAMA5D3 processor allows the use of CryptoDev Linux drivers to speed up the OpenSSL implementation. The Wi-Fi module — powered by Atmel’s WILC3000 single-chip solution — also supports the IEEE 802.11 WEP, WPA and WPA2 security mechanisms.

The smart router of DAB-Embedded employs Active-Semi’s ACT8945AQJ305-T power management IC, but the real surprise is Altera’s MAX 10 FPGA with an integrated analog-to-digital converter (ADC). That brings the additional flexibility for the main CPU: Atmel’s SAMA5D36.

The FPGA is connected to the 16-bit external bus interface (EBI) so that IoT developers can put any IP core in FPGA for communication with external sensors. All data is converted inside the FPGA to a specific format by using NIOS II’s soft CPU in FPGA. Next, the SAMA5D36 processor reads this data by employing DMA channel over the high-speed mezzanine card (HSMC) bus.

An FPGA has enough cells to start even two soft cores for data preprocessing. Case in point: A weather station with 8-channel external ADC managing light sensors, temperature sensors, pressure sensors and more. It’s connected to the FPGA together with PPS signal from GPS for correct time synchronization of each measurement.

Router.png

OpenWRT Framework

The SAMA5D36 embedded processor enables DAB’s smart router design to customize free OpenWRT Linux firmware according to the specific IoT application needs. The OpenWRT framework facilitates an easy way to set up router-like devices equipped with communications interfaces such as dual-port Ethernet and Wi-Fi connection.

What’s more, by using the OpenWRT framework, an IoT developer can add now his or her own application (C/C++) to exchange data with a KNX or Z-Wave transceiver. OpenWRT even supports the Lua embedded interpreter.

Next, while DAB-Embedded has built its smart router using the embedded Linux with OpenWRT framework, Belgium’s design house also offers a board support package (BSP) based on the Windows Embedded Compact 2013 software. That’s for IoT developers who have invested in Windows applications and want to use them on the new hardware: the DAB-OWRT-53 smart router.

Later, the embedded design firm plans to release smart router hardware based on the Windows 10 IoT software and Atmel’s SAMA5D family of embedded processors. The Belgian developer of IoT products has vowed to release the second version of its router board based on Atmel’s SAMA5D4 embedded processor and WILC3000 chipset that comes integrated with power amplifier, LNA, switch and power management. Atmel’s WILC3000 single-chip solution boasts IEEE 802.11 b/g/n RF/baseband/MAC link controller and Bluetooth 4.0 connection.


Majeed Ahmad is the author of books Smartphone: Mobile Revolution at the Crossroads of Communications, Computing and Consumer Electronics and The Next Web of 50 Billion Devices: Mobile Internet’s Past, Present and Future.

The power of the platform in IoT and wearable designs


What IoT developers want? A candid look at the wearable designs shows how platform approach is helping design engineers confront daunting challenges in the IoT arena.


“Providers become platforms” is the second most prominent finding of the Forbes story entitled “The Five Most Disruptive Innovations at CES 2016.” Interestingly, all the five disrupting forces outlined in the story relate to the Internet of Things blaze one way or the other. A coincidence? Not really.

CES 2016 was mostly about demonstrating how the advent of a connected world is possible with the creation of an array of smart and interconnected devices. However, the IoT juggernaut, while exploring the true value of connectivity, also requires new business models, which in turn, makes time-to-market even more critical.

Smart badge brings efficiency in enterprise, hospitality and healthcare

Take smart wearable devices, for instance, which were arguably the biggest story on the CES floor this year. A wearable design comprises of one or more sensors, connectivity solution like a radio controller, a processor to carry out system-level functions, storage to log information, display and battery. And what IoT and wearable developers want?

A platform that allows them to facilitate the finished products quickly and efficiently. The design engineers simply can’t afford experimentation with the basic blocks as they need a precedence of basic hardware and software functions working efficiently and smoothly.

Anatomy of Wearable Design

First and foremost, wearable designs confront power constraints even greater than mobile devices. Not surprisingly, ultra-low-power MCUs lie at the heart of wearable designs because they combine flash, on-chip RAM and multiple interface options while intelligently turning power on and off during activity and idle periods, respectively.

The next design conundrum relates to the form factor because these devices are being worn, so they have to be small and light. That, in turn, demands even smaller circuit boards with a greater level of integration. Enter the IoT platforms.

Amid power, performance and form factor considerations, the choice of a right IoT platform means that designers will most likely get the basic building blocks right. And that will allow IoT developers to focus on the application, differentiation and customer needs.

That’s what Atmel is aiming for with the launch of a reference platform for cost-optimized IoT and wearable applications. Atmel’s ultra-low-power platform, which was announced over the week of CES, is aimed at battery-operated wearable devices requiring activity and environment monitoring.

Power has a critical role in the key IoT building blocks

IoT Developer Platform

Below are the key highlights of Atmel’s platform offering for the IoT and wearable designs.

Processor: Microcontroller’s low-power requirements make it a likely choice in wearable designs; MCUs that communicate and process sensor inputs draw very little power from the battery while asleep. Remember the L21 microcontroller that made headlines back in 2015 after leading the low-power benchmarks conducted by EEMBC ULPBench.

Atmel’s SMART SAM L21 MCU — based on ARM’s lowest power Cortex-M0+ processing core — scored 185 in the benchmark and was able to bring the power consumption down to 35µA/MHz in active mode and 200nA in sleep mode.

Communications: The BTLC1000 is an ultra-low power Bluetooth Smart (BLE 4.1) system-on-chip (SoC) that comes integrated with ARM Cortex-M0 core, transceiver, modem, MAC, power amplifier, TR switch, and power management unit (PMU). It can be used as a BLE link controller or data pump with external host MCU or as a standalone applications processor with embedded BLE connectivity and external memory.

Atmel claims that its BTLC1000 Bluetooth solution — a 2.2mm x 2.1mm wafer level chip scale package — is 25 percent smaller than the nearest competitor solution. And Electronic Products magazine has corroborated that premise by calling it the lowest power BLE chipset that consumes less than 4mA in RX and less than 3mA in TX at 0dbm.

Security: Atmel is among the first chipmakers to offer specialized security hardware for the IoT market. Its microcontrollers come integrated with anti-cloning, authentication and encryption features.

Display: Wearable devices often show data such as time, measurements, maps and notifications on a display, and here, capacitive touch provides a very intuitive form of interfacing with the information. Atmel’s MCUs can directly manage capacitive buttons through software libraries that the firm provides.

Furthermore, Atmel offers standalone display controllers that support capacitive button, slider and wheel (BSW) implementations. These touch solutions can be tuned to moisture environments, a key requirement for many wearable applications. Atmel’s maXTouch capacitive touchscreen controller technology is a leading interface solution for its low-power consumption, precision and sensitivity.

Sensors: The development framework for the wearable designs features BHI160 6-axis SmartHub motion sensor and BME280 environment sensor from Bosch. It’s worth noting that Bosch is one of Atmel’s sensor partners. However, wearable product designers are free to pick sensors of their choice from Atmel’s other sensor partners.

Software support: The software package includes RTOS, Atmel’s Studio 7 IDE and Atmel START, which Atmel claims is the world’s first intuitive web-based tool for software configuration and code generation. Moreover, Atmel Software Framework (ASF) offers communication libraries for Bluetooth radios.

Atmel's developer platform for IoT and wearable designs

The truth is that the design game has moved from hardware and software functional blocks to complete developer ecosystems since the iPhone days. Now the ecosystem play is taking platforms to a whole new level in the design diversity that comes with the IoT products.

The choice of a right IoT platform means that designers will most likely get the basic building blocks right, and then, they can focus on the application and customer needs. It also provides design engineers space for differentiation, a critical factor in making wearable devices a consumer success.

 

 

Security coprocessor marks a new approach to provisioning for IoT edge devices


It’s worth noting that security breaches rarely involve breaking the encryption code; hackers mostly use techniques like spoofing to steal the ID.


The advent of security coprocessor that offloads the provisioning task from the main MCU or MPU is bringing new possibilities for the Internet of Things product developers to secure the edge device at lower cost and power points regardless of the scale.

Hardware engineers often like to say that there is now such thing as software security, and quote Apple that has all the money in the world and an army of software developers. The maker of the iPhone chose a secure element (SE)-based hardware solution while cobbling the Apple Pay mobile commerce service. Apparently, with a hardware solution, engineers have the ecosystem fully in control.

sec-1

Security is the basic building block of the IoT bandwagon, and there is a lot of talk about securing the access points. So far, the security stack has largely been integrated into the MCUs and MPUs serving the IoT products. However, tasks like encryption and authentication take a lot of battery power — a precious commodity in the IoT world.

Atmel’s solution: a coprocessor that offloads security tasks from main MCU or MPU. The ATECC508A uses elliptic curve cryptography (ECC) capabilities to create secure hardware-based key storage for IoT markets such as home automation, industrial networking and medical. This CryptoAuthentication chip comes at a manageable cost — 50 cents for low volumes — and consumers very low power. Plus, it makes provisioning — the process of generating a security key — a viable option for small and mid-sized IoT product developers.

A New Approach to Provisioning

It’s worth noting that security breaches rarely involve breaking the encryption code; hackers mostly use techniques like spoofing to steal the ID. So, the focus of the ATECC508A crypto engine is the tasks such as key generation and authentication. The chip employs ECC math to ensure sign-verify authentication and subsequently the verification of the key agreement.

The IoT security — which includes the exchange of certificates and other trusted objects — is implemented at the edge node in two steps: provisioning and commissioning. Provisioning is the process of loading a unique private key and other certificates to provide identity to a device while commissioning allows the pre-provisioned device to join a network. Moreover, provisioning is carried out during the manufacturing or testing of a device and commissioning is performed later by the network service provider and end-user.

Atmel ATECC508A crypto-engine

Presently, snooping threats are mostly countered through hardware security module (HSM), a mechanism to store, protect and manage keys, which requires a centralized database approach and entails significant upfront costs in infrastructure and logistics. On the other hand, the ATECC508A security coprocessor simplifies the deployment of secure IoT nodes through pre-provisioning with internally generated unique keys, associated certificates and certification-ready authentication.

It’s a new approach toward provisioning that not only prevents over-building, as done by the HSM-centric techniques, but also prevents cloning for the gray market. The key is controlled by a separate chip, like the ATECC508A coprocessor. Meaning, if there are 1,000 IoT systems to be built, there will be exactly 1,000 security coprocessors for them.

Certified-ID Security Platform

Back at ARM TechCon 2015, Atmel went one step ahead when it announced the availability of Certified-ID security platform for the IoT entry points like edge devices to acquire certified and trusted identities. This platform leverages internal key generation capabilities of the ATECC508A security coprocessor to deliver distributed key provisioning for any device joining the IoT network. That way it enables a decentralized secure key generation and eliminates the upfront cost of building the provisioning infrastructure for IoT setups being deployed at smaller scales.

AT88CKECCROOT-SIGNER

Atmel, a pioneer in Trusted Platform Module (TPM)-based secure microcontrollers, is now working with cloud service providers like Proximetry and Exosite to turn its ATECC508A coprocessor-based Certified-ID platform into an IoT edge node-to-cloud turnkey security solution. TPM chips, which have roots in the computer industry, aren’t well-positioned to meet the cost demands of low-price IoT edge devices.

Additionally, the company has announced the availability of two provisioning toolkits for low volume IoT systems. The AT88CKECCROOT toolkit is a ‘master template’ that creates and manages certificate root of trust in any IoT ecosystem. On the other hand, AT88CKECCSIGNER is a production kit that allows designers and manufacturers to generate tamper-resistant keys and security certifications in their IoT applications.

mbed eval boards showcase focus on IoT software and connectivity


Chipmakers like Atmel are joining hands with ARM to bring the entire ecosystem under one roof and thus facilitate the creation of standards-based IoT products.


ARM’s mbed operating system is winning attention in the highly fragmented embedded software space by promising a solid software foundation for interoperable hardware and thus scale the Internet of Things designs by narrowing the development time.

Atmel has put its weight behind ARM’s mbed OS by launching the single-chip evaluation board for the IoT ecosystem in a bid to ensure low software dependence for the embedded developers. The leading microcontroller supplier unveiled the mbed evaluation platform at the recent ARM TechCon held in Santa Clara, California.

The mbed OS platform is focused on rapid development of connected devices with an aim to create a serious professional platform to prototype IoT applications. So IoT developers don’t have to look to software guys for help. The mbed stack features a strong focus on enhancing the IoT’s connectivity and software components.

Atmel mbed Xpro board

ARM is the lead maintainer for the mbed OS modules while it adds silicon partners, like Atmel, as platform-specific dependencies for the relevant mbed OS modules. Silicon partners are responsible for their platform-specific drivers.

Atmel’s mbed-enabled evaluation board is based on the low-power 2.4GHz wireless Cortex-M0+ SAM R21 MCU. Moreover, Atmel is expanding mbed OS support for its Wi-Fi modules and Bluetooth Low Energy products.

The fact that Atmel is adding mbed OS to its IoT ecosystem is an important nod for ARM’s mbed technology in its journey from merely a hardware abstraction layer to a full-fledged IoT platform. Atmel managers acknowledge that mbed technology adds diversity to embedded hardware devices and makes MCUs more capable.

Solid Software Foundation

There is a lot of code involved in the IoT applications and software is getting more complex. It encompasses, for instance, sensor library to acquire data, authentication at IoT gateways and SSL security. Here, the automatic software integration engine like mbed lets developers focus on their applications instead of worrying about integrating off-the-shelf software.

The mbed reference designs like the one showcased by Atmel during ARM TechCon are aimed at narrowing the development time with the availability of building blocks and design resources—components, code and infrastructure—needed to bootstrap a working IoT system. Atmel managers are confident that a quality software foundation like mbed could help bring IoT products to market faster.

thingsquare2

Atmel’s mbed-enabled IoT evaluation board promises harmony between hardware and software. Apparently, chipmakers like Atmel are joining hands with ARM to bring the entire ecosystem — OS software, cloud services and developer tools — under one roof, and thus facilitate the creation of standards-based IoT products. Atmel’s mbed evaluation board clearly mirrors that effort to deliver a complete hardware, software and developer tools ecosystem in order to bring IoT designs quicker to market.

The platform comprises of mbed OS software for IoT client devices like gateways and mbed Device Server for the cloud services. ARM launched the mbed software platform in 2014 and Atmel has been part of this initiative since then.

mbed in Communications Stack

Additionally, Atmel has tied the mbed association to its SmartConnect wireless solutions to make the best of mbed’s networking stack in the Internet of connected things. The IoT technology is built on layers, and here, interoperability of communications protocols is a key challenge.

For a start, Atmel’s SAM R21-Xpro evaluation board is embed-enabled and is built around the R21 microcontroller, which has been designed for industrial and consumer wireless applications running proprietary communication stacks or IEEE 802.15.4-compliant solutions.

Next up, the evaluation board includes SAM W25 Wi-Fi module that integrates IEEE 802.11 b/g/n IoT network controller with the existing MCU solution, SAM D21, which is also based on the Cortex-M0+ processor core.

XPLAIN
Furthermore, Atmel is offering an mbed-enabled Bluetooth starter kit that includes SAM L21 microcontroller-based evaluation board and ultra-low-power Bluetooth chip BTLC1000, which is compliant with Bluetooth Low Energy 4.1. Atmel demonstrated a home lighting system at the ARM TechCon show floor, which employed SAM R21-based Thread routers that passed light sensor information to an mbed-enabled home gateway. Subsequently, this information was processed and sent to the mbed Device Server using a web interface.


Majeed Ahmad is the author of books Smartphone: Mobile Revolution at the Crossroads of Communications, Computing and Consumer Electronics and The Next Web of 50 Billion Devices: Mobile Internet’s Past, Present and Future.

Profile of an IoT processor for the industrial and consumer markets


 If there’s a single major stumbling block that is hindering the IoT take-off at the larger industrial scale, it’s security.


The intersection of data with intelligent machines is creating new possibilities in industrial automation, and this new frontier is now being increasingly known as the Industrial Internet of Things (IIoT). However, if there is a single major stumbling block that is hindering the IoT take-off at the larger industrial scale, it’s security.

It’s imperative to have reliable data in the industrial automation environment, and here, the additional security layers in the IoT hardware often lead to compromises in performance. Then, there is counterfeiting of products and application software, which is becoming a growing concern in the rapidly expanding IoT market.

sama5d2_google_1160x805_090215

Atmel’s answer to security concerns in the IIoT infrastructure: a microprocessor (MPU) that can deliver the security while maintaining the level of performance that Internet-connected systems require. The company’s Cortex A5 chip — the Atmel | SMART SAMA5D4 — securely stores and transfers data, as well as safeguards software assets to prevent cloning of IoT applications.

The SAMA5D4 series of MPUs enables on-the-fly encryption and decryption of software code from the external DRAM. Moreover, it boasts security features such as secure boot, tamper detection pins and safe erasure of security-critical data. The A5D4 processor also incorporates ARM’s system-wide security approach, TrustZone, which is used to secure peripherals such as memory and crypto blocks. TrustZone —comprising of security extensions that can be implemented in a number of ARM cores — is tightly integrated into ARM’s Cortex-A processors. It runs the processor in two different modes: First, a secure environment executes critical security and safety software, and secondly, a normal environment runs the rich OS software applications such as Linux. This lets embedded designers isolate critical software from OS software.

The system approach allows control access to CPU, memories, DMA and peripherals with programmable secure regions. That, in turn, ensures that on-chip parts like CPU and off-chip parts like peripherals are protected from software attacks.

Trust

Performance Uplift

The Atmel SMART | SAMA5D4 processor is based on the Cortex-A5, the smallest and simplest of the Cortex-A series cores that support the 32-bit ARMv7 instruction set. It’s targeted at applications requiring high-precision computing and fast signal processing — that includes industrial and consumer applications such as control panels, communication gateways and imaging terminals.

The use cases for SAMA5D4 span from kiosks, vending machines and barcode scanners, to smart grid, communications gateways and control panels for security, home automation, thermostats, etc. Atmel’s MPU features peripherals for connectivity and user interface applications. For instance, it offers a TFT LCD controller for human-machine interface (HMI) and control panel applications and a dual Ethernet MAC for networking and gateway solutions.

Apart from providing high-grade security, SAMA5D4 adds two other crucial features to address the limitations of its predecessor, SAMA5D3 processor. First, it uplifts performance through ARM’s NEON DSP engine and 128kB L2 cache. The NEON DSP with 128-bit single instruction, multiple data (SIMD) architecture accelerates signal processing for more effective handling of multimedia and graphics. Likewise, L2 cache enhances data processing capability for imaging applications.

The second prominent feature of the SAMA5D4 is video playback that boasts 720p resolution hardware video decoder with post-image processing capability. Atmel’s embedded processor offers video playback for H.264, VP8 and MPEG4 formats at 30fps.

A Quick Overview of the SAMA5D4

The SAMA5D4 processor, which got a 14 percent performance boost from its predecessor MPU, increasing operating speed to 528 MHz, is a testament of the changing microprocessor market in the IoT arena. Atmel’s microprocessor for IoT markets delivers 840 DMIPS that can facilitate imaging-centric applications hungry for processing power. Aside from that, the SAMA5D4 is equipped with a 32-bit wide DDR controller running up to 176 MHz, which can deliver up to 1408MB/s of bandwidth. That’s a critical element for high-speed peripherals common in the industrial environments where microprocessors are required to process large amounts of data.

sama5d4-block-diagram_734x612_large

Finally, the SAMA5D4 is configurable in either a 16- or 32-bit bus interface allowing developers a trade-off between performance and memory cost. There are four distinct chips in the SAMA5D4 family: SAMA5D41 (16-bit DDR), SAMA5D42 (32-bit DDR), SAMA5D43 (16-bit DDR along with H.264 video decoder)and SAMA5D44 (32-bit DDR along with H.264 video decoder).

The SoC-specific hardware security and embedded vision capabilities are a stark reminder of specific requirements of different facets of IoT, in this case, industrial and consumers markets. And Atmel’s specific focus on security and rich media just shows how the semiconductor industry is getting around the key IoT stumbling blocks.


Majeed Ahmad is the author of books Smartphone: Mobile Revolution at the Crossroads of Communications, Computing and Consumer Electronics and The Next Web of 50 Billion Devices: Mobile Internet’s Past, Present and Future.

4 designs tips for AVB in-car infotainment


AVB is clearly the choice of several automotive OEMs, says Gordon Bechtel, CTO, Media Systems, Harman Connected Services.


Audio Video Bridging (AVB) is a well-established standard for in-car infotainment, and there is a significant amount of activity for specifying and developing AVB solutions in automobiles. The primary use case for AVB is interconnecting all devices in a vehicle’s infotainment system. That includes the head unit, rear-seat entertainment systems, telematics unit, amplifier, central audio processor, as well as rear-, side- and front-view cameras.

The fact that these units are all interconnected with a common, standards-based technology that is certified by an independent market group — AVnu — is a brand new step for the automotive OEMs. The AVnu Alliance facilitates a certified networking ecosystem for AVB products built into the Ethernet networking standard.

Figure 1 - AVB is an established technology for in-car infotainmentAccording to Gordon Bechtel, CTO, Media Systems, Harman Connected Services, AVB is clearly the choice of several automotive OEMs. His group at Harman develops core AVB stacks that can be ported into car infotainment products. Bechtel says that AVB is a big area of focus for Harman.

AVB Design Considerations

Harman Connected Services uses Atmel’s SAM V71 microcontrollers as communications co-processors to work on the same circuit board with larger Linux-based application processors. The software firm writes codes for customized reference platforms that automotive OEMs need to go beyond the common reference platforms.

Based on his experience of automotive infotainment systems, Bechtel has outlined the following AVB design dos and don’ts for the automotive products:

1. Sub-microsecond accuracy: Every AVB element on the network is hooked to the same accurate clock. The Ethernet hardware should feature a time stand to ensure packet arrival in the right order. Here, Bechtel mentioned the Atmel | SMART SAM V71 MCU that boasts screen registers to ensure advanced hardware filtering of inbound packets for routing to correct receive-end queues.

2. Low latency: There is a lot of data involved in AVB, both in terms of bit rate and packet rate. AVB allows low latency through reservations for traffic, which in turn, facilitate faster packet transfer for higher priority data. Design engineers should carefully shape the data to avoid packet bottlenecks as well as data overflow.

Figure 2 - Bechtel

Bechtel once more pointed to Atmel’s SAM V71 microcontrollers that provide two priority queues with credit-based shaper (CBS) support that allows the hardware-based traffic shaping compliant with 802.1Qav (FQTSS) specifications for AVB.

3. 1588 Timestamp unit: It’s a protocol for correct and accurate 802.1 AS (gPTP) support as required by AVB for precision clock synchronization. The IEEE 802.1 AS carries out time synchronization and is synonymous with generalized Precision Time Protocol or gPTP.

Timestamp compare unit and a large number of precision timer counters are key for the synchronization needed in AVB for listener presentations times and talker transmissions rates as well as for media clock recovery.

4) Tightly coupled memory (TCM): It’s a configurable high-performance memory access system to allow zero-wait CPU access to data and instruction memory blocks. A careful use of TCM enables much more efficient data transfer, which is especially important for AVB class A streams.

It’s worth noting that MCUs based on ARM Cortex-M7 architecture have added the TCM capability for fast and deterministic code execution. TCM is a key enabler in running audio and video streams in a controlled and timely manner.

AVB and Cortex-M7 MCUs

The Cortex-M7 is a high-performance core with almost double the power efficiency of the older Cortex-M4. It features a six-stage superscalar pipeline with branch prediction — while the M4 has a three-stage pipeline.  Bechtel of Harman acknowledged that M7 features equate to more highly optimized code execution, which is important for Class A audio implementations with lower power consumption.

Again, Bechtel referred to the SAM V71 MCUs — which are based on the Cortex-M7 architecture — as particularly well suited for the smaller ECUs. “Rear-view cameras and power amplifiers are good examples where the V71 microcontroller would be a good fit,” he said. “Moreover, the V71 MCUs can meet the quick startup requirements needed by automotive OEMs.”

Figure 3 - Atmel's V71 is an M7 chip for Ethernet AVB networking and audio processing

The infotainment connectivity is based on Ethernet, and most of the time, the main processor does not integrate Ethernet AVB. So the M7 microcontrollers, like the V71, bring this feature to the main processor. For the head unit, it drives the face plate, and for the telematics control, it contains the modem to make calls so echo cancellation is a must, for which DSP capability is required.

Take the audio amplifier, for instance, which receives a specific audio format that has to be converted, filtered and modulated to match the requirement for each specific speaker in the car. This means infotainment system designers will need both Ethernet and DSP capability at the same time, which Cortex-M7 based chips like V71 provide at low power and low cost.

6 memory considerations for Cortex-M7-based IoT designs


Taking a closer look at the configurable memory aspects of Cortex-M7 microcontrollers.


Tightly coupled memory (TCM) is a salient feature in the Cortex-M7 lineup as it boosts the MCU’s performance by offering single cycle access for the CPU and by securing the high-priority latency-critical requests from the peripherals.

Cortex-M7-chip-diagramLG

The early MCU implementations based on the ARM’s M7 embedded processor core — like Atmel’s SAM E70 and S70 chips — have arrived in the market. So it’d be worthwhile to have a closer look at the configurable memory aspects of M7 microcontrollers and see how the TCMs enable the execution of deterministic code and fast transfer of real-time data at the full processor speed.

Here are some of the key findings regarding the advanced memory architecture of Cortex-M7 microcontrollers:

1. TCM is Configurable

First and foremost, the size of TCM is configurable. TCM, which is part of the physical memory map of the MCU, supports up to 16MB of tightly coupled memory. The configurability of the ARM Cortex-M7 core allows SoC architects to integrate a range of cache sizes. So that industrial and Internet of Things product developers can determine the amount of critical code and real-time data in TCM to meet the needs of the target application.

The Atmel | SMART Cortex-M7 architecture doesn’t specify what type of memory or how much memory should be provided; instead, it leaves these decisions to designers implementing M7 in a microcontroller as a venue for differentiation. Consequently, a flexible memory system can be optimized for performance, determinism and low latency, and thus can be tuned to specific application requirements.

2. Instruction TCM

Instruction TCM or ITCM implements critical code with deterministic execution for real-time processing applications such as audio encoding/decoding, audio processing and motor control. The use of standard memory will lead to delays due to cache misses and interrupts, and therefore will hamper the deterministic timing required for real-time response and seamless audio and video performance.

The deterministic critical software routines should be loaded in a 64-bit instruction memory port (ITCM) that supports dual-issue processor architecture and provide single-cycle access for the CPU to boost MCU performance. However, developers need to carefully calibrate the amount of code that need zero-wait execution performance to determine the amount of ITCM required in an MCU device.

The anatomy of TCM inside the M7 architecture

The anatomy of TCM inside the M7 architecture.

3. Data TCM

Data TCM or DTCM is used in fast data processing tasks like 2D bar decoding and fingerprint and voice recognition. There are two data ports (DTCMs) that provide simultaneous and parallel 32-bit data accesses to real-time data. Both instruction TCM and data TCM — used for efficient access to on-chip Flash and external resources — must have the same size.

4. System RAM and TCM

System RAM, also known as general RAM, is employed for communications stacks related to networking, field buss, high-bandwidth bridging, USB, etc. It implements peripheral data buffers generally through direct memory access (DMA) engines and can be accessed by masters without CPU intervention.

Here, product developers must remember the memory access conflicts that arise from the concurrent data transfer to both CPU and DMA. So developers must set clear priorities for latency-critical requests from the peripherals and carefully plan latency-critical data transfers like the transfer of a USB descriptor or a slow data rate peripheral with a small local buffer. Access from the DMA and the caches are generally burst to consecutive addresses to optimize system performance.

It’s worth noting that while system memory is logically separate from the TCM, microcontroller suppliers like Atmel are incorporating TCM and system RAM in a single SRAM block. That lets IoT developers share general-purpose tasks while splitting TCM and system RAM functions for specific use cases.

A single SRAM block for TCM and system memory allows higher flexibility and utilization

A single SRAM block for TCM and system memory allows higher flexibility and utilization.

5. TCM Loading

The Cortex-M7 uses a scattered RAM architecture to allow the MCU to maximize performance by having a dedicated RAM part for critical tasks and data transfer. The TCM might be loaded from a number of sources, and these sources aren’t specified in the M7 architecture. It’s left to the MCU designers whether there is a single DMA or several data loading points from various streams like USB and video.

It’s imperative that, during the software build, IoT product developers identify which code segments and data blocks are allocated to the TCM. This is done by embedding programs into the software and by applying linker settings so that software build appropriately places the code in memory allocation.

6. Why SRAM?

Flash memory can be attached to a TCM interface, but the Flash cannot run at the processor clock speed and will require caching. As a result, this will cause delays when cache misses occur, threatening the deterministic value proposition of the TCM technology.

DRAM technology is a theoretical choice but it’s cost prohibitive. That leaves SRAM as a viable candidate for fast, direct and uncached TCM access. SRAM can be easily embedded on a chip and permits random accesses at the speed of the processor. However, cost-per-bit of SRAM is higher than Flash and DRAM, which means it’s critical to keep the size of the TCM limited.

Atmel | SMART Cortex-M7 MCUs

Take the case of Atmel’s SMART SAM E70, S70 and V70/71 microcontrollers that organize SRAM into four memory banks for TCM and System SRAM parts. The company has recently started shipping volume units of its SAM E70 and S70 families for the IoT and industrial markets, and claims that these MCUs provide 50 percent better performance than the closest competitor.

SAM-E70_S70_BlockDiagram_Lg_929x516

Atmel’s M7-based microcontrollers offer up to 384KB of embedded SRAM that is configurable as TCM or system memory for providing IoT designs with higher flexibility and utilization. For instance, E70 and S70 microcontrollers organize 384KB of embedded SRAM into four ports to limit memory access conflicts. These MCUs allocate 256KB of SRAM for TCM functions — 128 KB for ITCM and DTCM each — to deliver zero wait access at 300MHz processor speed, while the remaining 128KB of SRAM can be configured as system memory running at 150MHz.

However, the availability of an SRAM block organized in the form of a memory bank of 384KB means that both system SRAM and TCM can be used at the same time.The large on-chip SRAM of 384KB is also critical for many IoT devices, since it enables them to run multiple communication stacks and applications on the same MCU without adding external memory. That’s a significant value proposition in the IoT realm because avoiding external memories lowers the BOM cost, reduces the PCB footprint and eliminates the complexity in the high-speed PCB design.