The power of the platform in IoT and wearable designs

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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.

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“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.

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.

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.

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.

 

 

Atmel’s SAM L21 MCU for IoT tops low power benchmark

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SAM L21 MCUs consume less than 940nA with full 40kB SRAM retention, real-time clock and calendar, and 200nA in the deepest sleep mode.

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The Internet of Things (IoT) juggernaut has unleashed a flurry of low-power microcontrollers, and in that array of energy-efficient MCUs, one product has earned the crown jewel of being the lowest-power Cortex M-based solution with power consumption down to 35µA/MHz in active mode and 200nA in sleep mode.

How do we know if Atmel’s SAM L21 microcontroller can actually claim the leadership in ultra-low-power processing movement? The answer lies in the EEMBC ULPBench power benchmark that was introduced last year. It ensures a level playing field in executing the benchmark by having the MCU perform 20,000 clock cycles of active work once a second and sleep the remainder of the second.

 

ULPBench shows SAM L21 is lower power than any of its competitor’s M0+ class chips.

Atmel has released the ultra-low-power SAM L21 MCU it demonstrated at Electronica in Munich, Germany back in November 2014. Architectural innovations in the SAM L21 MCU family enable low-power peripherals — including timers, serial communications and capacitive touch sensing — to remain powered and running while the rest of the system is in a reduced power mode. That further reduces power consumption for always-on applications such as fire alarms, healthcare, medical and connected wearables.

Next, the 32-bit ARM-based MCU portfolio combines ultra-low-power with Flash and SRAM that are large enough to run both the application and wireless stacks. Collectively, these three features make up the basic recipe for battery-powered mobile and IoT devices for extending their battery life from years to decades. Moreover, they reduce the number of times batteries need to be changed in a plethora of IoT applications.

Low Power Leap of Faith

Atmel’s SAM L21 microcontrollers have achieved a staggering 185.8 ULPBench score, which is way ahead of runner-up TI’s SimpleLink C26xx microcontroller family that scored 143.6. The SAM L21 microcontrollers consume less than 940nA with full 40kB SRAM retention, real-time clock and calendar, and 200nA in the deepest sleep mode. According to Atmel spokesperson, it comes down to one-third the power of competing solutions.

Markus Levy, President and Founder of EEMBC, credits Atmel’s low-power feat to its proprietary picoPower technology and the company’s low-power expertise in utilizing DC-DC conversion for voltage monitoring. Atmel’s picoPower technology employs flexible clocking options and short wake-up time with multiple wake-up sources from even the deepest sleep modes.

ULPBench aims to provide developers with a reliable methodology to test MCUs.

In other words, Atmel has taken the low-power game beyond architectural improvements to the CPU while optimizing nearly every peripheral to operate in standalone mode and then use a minimum number of transistors to complete the given task. Most lower-power ARM chips simply disable the clock to various parts of the device. The SAM L21 microcontroller, on the other hand, turns off power to those chip parts; hence, there is no leakage current in thousands of transistors in that part.

Here is a brief highlight of Atmel’s low-power development efforts that now encompass almost every peripheral in an MCU device:

Sleep Modes

Sleep modes not only gate away the clock signal to stop switching consumption, but also remove the power from sub-domains to fully eliminate leakage. Atmel also employs SRAM back-biasing to reduce leakage in sleep modes.

Consider a simple application where the temperature in a room is monitored using a temperature sensor with the analog-to-digital converter (ADC). In order to reduce the power consumption, the CPU would be put to sleep and wake up periodically on interrupts from a real-time counter (RTC). The measured sensor data is checked against a predefined threshold to decide on further action. If the data does not exceed the threshold, the CPU will be put back to sleep waiting for the next RTC interrupt.

SleepWalking

SleepWalking is a technology that enables peripherals to request a clock when needed to wake-up from sleep modes and perform tasks without having to power up the CPU Flash and other support systems. For instance, Atmel’s ultra-low-power capacitive touch-sensing peripheral can run in all operating modes and supports wake-up on a touch.

For the temperature monitoring application, as mentioned above, this means that the ADC’s peripheral clock will only be running when the ADC is converting. When the ADC receives the overflow event from the RTC, it will request its generic clock from the generic clock controller and peripheral clock will stop as soon as the ADC conversion is completed.

Event System

The Event System allows peripherals to communicate directly without involving the CPU and thus enables peripherals to work together to solve complex tasks using minimal gates. It allows system developers to chain events in software and use an event to trigger a peripheral without CPU involvement.

Again, taking temperature monitor as a use case, the RTC must be set to generate an overflow event, which is routed to the ADC by configuring the Event System. The ADC must be configured to start a conversion when it receives an event. By using the Event System, an RTC overflow can trigger an ADC conversion without waking up the CPU. Moreover, the ADC can be configured to generate an interrupt if the threshold is exceeded, and the interrupt will wake up the CPU.

Low Power MCU Use Case

Paul Rako has mentioned a sensor monitor in his recent post in Atmel’s Bits & Pieces blog. Rako writes in his post titled “The SAM L21 pushes the boundaries of low power MCUs” about this sensor monitor being asleep 99.99 percent of the time, waking up once a day to take a measurement and send it wirelessly to a host. Such tasks can be conveniently handled by an 8-bit device.

However, moving to IoT applications, which constitute protocol stacks, there is number crunching involved and that requires a faster ARM-class 32-bit chip. So, for battery-powered IoT applications, Rako makes the case for 32-bit ARM-based chip that can wake up, do its thing, and go back to sleep. If a high-current chip wakes up 10 times faster but uses twice the power, it will still use less energy and less charge than the slower chip.

Next, Rako presents sensor fusion hub as a case study in which the device saves power by skipping the radio chip to send the data from each sensor and instead uses the ARM-based microcontroller that does the math and pre-processing to combine the raw data from all sensors and then assembles the result as a simple chunk of data.

Atmel has scored an important design victory in the ongoing low-power game that is now prevalent in the rapidly expanding IoT market. Atmel already boasts credentials in the connectivity and security domains — the other two key IoT building blocks. Its connectivity solutions cover multiple wireless arenas — Bluetooth, Wi-Fi, Zigbee and 6LoWPan — to enable IoT communications.

Likewise, Atmel’s CryptoAuthentication devices come with protected hardware key storage and are available with SHA256, AES128 or ECC256/283 cryptography. The IoT triumvirate of low power consumption, broad connectivity portfolio and crypto engineering puts Atmel in a strong position in the promising new market of IoT that is increasingly demanding low power portfolio of MCUs to be matched with high performance.

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Majeed Ahmad is 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.

Video: Vegard Wollan talks AVR and ARM low-power operation

In this segment of the series, the co-inventor of the AVR microcontroller chip talks about the famously low power that the chips consume.

I had heard that one of the clever things Atmel does to save memory power is that we turn on the memory, fetch four instruction op-codes then turn the memory off again. Now, if there is a branch in these four op-codes that change the program flow, well, we have to turn on the memory and grab another four instructions. But, you can imagine just how often that the chips are executing all for instructions, so that we get those four op codes for the power cost of one fetch.

Vegard Wollan jokes will fellow Norwegian Andreas Eieland [off camera] about divulging the secrets to Atmel’s ultra-low power.

Vegard confirmed that Atmel does this on both the latest AVR and on our Atmel | SMART ARM-based chips. I love this clip since this is where we break the 4th wall as Vegard jokes to the crew that I am giving away too many secrets. I also confirmed that some of our ARM chips have a switching regulator controller built in. For instance, the SAM4L has one switching and one linear regulator built in. Now we don’t put any giant inductors inside the chip, you supply the external inductor, but all the control circuitry is available so you can really minimize the BOM (bill-of-materials).

To allow single-supply operation the ARM-based SAM4L microcontroller has a switching regulator on board, you only need to supply an external inductor.

This is yet another thing that differentiates our ARM-core parts from the competition. Most engineers know how cool and revolutionary the AVR was, but we have applied all the “cool” and more to our ARM-based chips. As Vegard noted, we have many tricks and innovations to sip the lowest amount of power, and that includes having our own processes at our Colorado Springs fabrication facility.