The New Face Of MCUs

For years, the humble microcontroller was known as the workhorse of white goods and other embedded applications that required some amount of processing, but not as much as a microprocessor would provide.

Much has changed since then. Today’s MCUs are the star components in fast-growing and increasingly sophisticated application areas such as automotive, smartphones and the Internet of Things – all while maintaining their low power and high efficiency attributes.

Tony Massimini, chief of technology for micrologic at Semico Research, noted that in terms of volume, the biggest market for microcontrollers is still IC cards, and from a revenue perspective the biggest market is still automotive.

“But it’s that whole industrial and consumer space that has a lot of promise,” Massimini said. “You’ve got more and more microcontrollers being designed for portability. What has happened in the last few years has been growth in smart phones that have sensors and a lot of context awareness. The microcontrollers are the center hub controller. The most notable one is NXP’s ARM controller, which was re-labeled M7 in the iPhone 5. There are others, as well, who have similar solutions, most notably STMicroelectronics, Freescale, and anybody that has a 32-bit MCU core from ARM is in this market. This is where a lot of complex algorithms are able to use the performance of the ARM cores, which also offer low-power — that is very key because in addition to smart phones the next step that they are broadening out into is wearable devices.”

The biggest players in this market include ST, Microchip, Atmel, Freescale, NXP, which along with others offer MCUs based on ARM MCU cores.

Historically, 8- and 16-bit microcontrollers mainly have been used in wearables due to power consumption reasons and the fact that they did not need the level of processing power of 32-bit. But, Massamini observed, in the last few months there has been a big move to push 32-bit into wearables and IoT applications. At CES, for example, Bosch showed a wireless sensor node with a 32-bit microcontroller plus lots of sensors to do context awareness.

Jason Tollefson, senior product marketing manager for the MCU16 division at Microchip Technology, noted that MCUs have evolved to include programmability, flash memory and larger memories, which also increase the accompanying software complexity.

A decade ago, everything was primarily digital, but now the MCU is all about the integration of hardware peripherals, said Brett Novak, principal marketing engineer in the MCU32 division at Microchip. “Now the comparators and A-to-Ds are all standard – they are commonplace. But we’ve taken a step further and are integrating more what we call intelligent analog, so the bread-and-butter type analog components such as op amps and voltage references are now being integrated onto the microcontroller itself. Discrete op amps and discrete analog are always going to have a place. They are higher performance, they’re highly specialized, but most of these applications that we find ourselves into are looking for bread-and-butter type analog. They don’t need the best performance or the fastest response time. They just need general-purpose specifications. That’s the kind of hardware we’re integrating onto the microcontroller itself.”

Taking that even further, there is also activity to remove the CPU from the application in a lot of respects, he said, because the peripherals integrated now are core-independent, so all of the different peripherals being integrated are autonomous to the core. “For example, maybe I have certain peripherals that are driving the LED and they’re feeding back into the micro using the analog but the CPU is typically not even involved. The CPU only intervenes when it recognizes that there is an issue or that there is an interrupt or it needs to go and react to something. The advantage is that the core can go off and do other things so while I am driving that LED — basically I’m running a touchpad or maybe am running some safety software in the background — but that’s the advantage that we provide. We’ve actually raised the ceiling of what you can do with an 8-bit core. We’re the thing in ‘the Internet of Things.’”

Thomas Ensergueix, senior product marketing manager at ARM, agreed. “If you compare [MCUs] to 10 years ago, it’s a quantum leap in terms of complexity.” He said MCUs are extremely flexible and come in different flavors, ranging from basic with only a few peripherals and a few pins all the way to the high end where there are number of peripherals integrated, including Ethernet, USB, sometimes wireless connectivity, a big number of timers, and a big number of cell communications. “It’s really incredible when you download one of the user manuals for the latest MCUs from Atmel, Freescale, ST — it is 1,000 pages thick. If I was an engineer designing stuff today I would be completely lost.”

Ensergueix said that increasingly, MCU suppliers will provide software to abstract out the complexity. “We have an abstraction layer called CMSIS (Cortex M Standard Interface Software), and thanks to this software API, which is standard across all the MCUs that embed a Cortex M processor, we remove the complexity of the peripherals of the core. This is more for the lowest layer of software on top of the MCUs, but you see also now more and more activities in terms of the firmware. In the past people tended to do everything by themselves, programming every layer on the MCUs, but you cannot master all the software stacks needed to make an advanced project using one of the latest MCUs. You cannot be experienced at USB, you cannot be experienced at Ethernet, you cannot be experienced in RTOS, you cannot be experienced in all of the wireless conductivities like Zigbee, Bluetooth LE. You have to rely on the availability of the software stack.”

The ‘thing’ in the Internet of Things
Indeed, Massimini confirmed, the foundation for the IoT at the edge devices is a sensor, a microcontroller, and connectivity of some kind, which could be wired or wireless.

Again, the flexibility of the devices makes them well suited for a variety of applications. And because of their low power, MCUs are more appropriate than an application processor in some applications – like wearable devices, according to Ensergueix.

“In fact, today the big innovations in terms of applications it’s more driven by the innovative startups,” he said. “Of all of the new wearables on the market like the Fitbit, etc., when you look at all the teardown of the wearables in 90% of the cases you will find a generic cortex M-based MCU.”

MCUs are the basic enablers of innovation across the Internet of Things.

“You are going to have well-known products in your home, in your car, on your wrist, that are now connected,” said Renaud Bouzereau, MCU product marketing manager at STMicroelectronics. “These products need maybe to keep the same form factor, which means that we need to put more value inside the product. — more connectivity, more features — without increasing the form factor. This is very applicable to wearable devices that are connected. More features mean that we need to put more performance in our product. Also, form factor means that we have to make small products for small packages like CSP (chip-scale package). And especially for wearables, we need to have ultra low power and dynamic efficiency. These are two very different concepts.”

For ultra low power, Bouzereau noted that ST tries to achieve the lowest power consumption figures with flexibility of architecture, flexibility of peripherals, as well as an optimized process. “The goal is to achieve the lowest figures in terms of power consumption, run mode, standby mode and flexible architecture. But then you can attack performance – for some applications you need the concept of dynamic efficiency, which is actually the best combination of performance and power consumption in run mode. For applications that are always on, you need tight optimization of performance and power.”

Automotive MCUs continue pushing ahead
The use of MCUs in the automotive space has led the way for some time, but even here there are new opportunities for more sophisticated applications of MCUs. That also translates to a higher value for the MCU provider. “In a car you can expect today from 50 to 100 electronic control units (ECUs), and you are very lucky to have in each of these at least one MCU,” said ARM’s Ensergueix. “An interesting thing is now the automotive industry just came to a point where having this big number of ECUs from a system point of view is quite difficult to program and to test because there are so many entities which are interacting. We see here a trend where people have an interest and incentive to reduce the number of ECUs, to group them, and instead add more higher performance processors to it, which combines multiple functionalities.”

This trend towards more performance and the ability to run on multiple tasks on the same MCU and prevent them from corrupting each other drove ARM to release its ARMv8-R [‘R’ for real time], which introduces vectorization.

In conclusion, Semico’s Massimini observed that with the new markets emerging for microcontrollers, because it is such a huge opportunity, many of the general-purpose microcontrollers will become more specialized for the sensor interfaces. “Whether or not a company will continue to market it as an MCU or put it in the SoC category is debatable. Then of course there will be others who come along who will challenge the entire microcontroller architecture with things like an FPGA or a specialized device. There is going to be within that sensor hub a segment, if you will, of specialized 32-bit microcontrollers, and they will be challenged by new devices, as well. But it is opening up a new market for microcontrollers in general.”

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See below for a sampling of products containing microchips

(Source: STMicroelectronics)

(Source: STMicroelectronics)

(Source: STMicroelectronics)