What’s up with the latest slew of low power MCUs?

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Q. Since a microcontroller can spend substantial amounts of time inactive, many designers use a ‘power budget’ to determine the average power consumption and to calculate the battery requirements. Your thoughts on this?
JT: Microchip’s free Battery Life Estimator provides MCU models to generate a report of the average current, the life of a battery in that configuration, and if the battery will support the modelled application. This allows trying different approaches to save power like whether it is better to run a portion of their code at full speed, to finish faster, or if running slower for longer gives lowest power consumption.

(Note that this is only a model. There are a lot of other variables involved, so bench trials are always important.)

VT: Yes, designers are using power budget these days to determine the power consumption and also to improve and calculate the battery performance and its further requirements. This is a good practice as one can check the performance of the battery and exactly know where it lags (if it does). This ensures good quality battery and also a longer life cycle.

ST: Power budget calculation is never an easy exercise. There are many aspects that need to be considered while working out the battery life estimate. Important parameters include:

– Battery self leakage

– Duty cycle calculation (active & sleep modes)

– Time duration during switching of different modes

– Optimised voltage & frequency levels

– Peripheral circuitry – power calculations (Iq Currents of active devices)

BHO: Power budgeting technique is certainly one of the method used to estimate the average power consumption. But one should not take this as accurate and make critical recommendation of a system’s operating hours based on particular battery type. Such estimation should take into consideration of other components on-board too and designers should not make calculation from MCU aspects only.

Q. What are the most exciting features that have come up to delight engineers, be it in the software for programming the MCU or the embedded peripherals within the MCU?
JT: Low power MCUs are now available with 16-bit Sigma-Delta ADCs built in. For communications we are seeing USB, CAN, and I2S™ being adopted in many ways. And finally, we are seeing small bits of programmable logic being added. This is great in that you can now stitch together peripherals in the manner you want within the MCU and have it operate in sleep mode at tiny current levels.

VT: In terms of peripherals, MCU now offer high resolution ADC upto 24 Bit Sigma delta ADC, high res. DAC, USB, Ethernet, high speed PWM’s, RTC, LCD controllers etc. In terms of programming all of them offer IDE and good compilers, we also offer Real time OS free with our 32 bit MCU’s.

ST: From a functionality perspective, we see increased analog peripherals optimised for certain end equipment or applications, being adapted by most suppliers making it a cost effective implementation (Op-Amps, 16-24bit ADCs, DACs) Also, connectivity is gaining ground across embedded applications and peripherals like Ethernet, CAN, USB and RF are increasing in most of their offerings.

BHO: Today, functions that are ‘Smart’ and ‘Connected’ are the much sort after functionalities in MCUs. For example, in Renesas RL78 Smart Analog series, analog front-end are integrated into the MCU. It is a new technology that allows interfacing to hundreds of sensor types with a single, configurable analog front end (AFE) platform – resulting in more intelligent sensors with a smaller footprint, while significantly reducing development time.

Q. “Internet of Things” is bringing about a significant wave of change in electronic devices. Are there MCUs that allow designers to easily build and link projects in the IoT space – an IoT application focused selection of MCUs perhaps?
JT: With the advent of low power radios that run in unison with the low power MCU and as technologies like Bluetooth LE are deployed, these “things” web connected intelligence can be enabled anywhere at very low cost. For example, Microchip has worked with companies such as Powercast™ to develop battery-less sensors powered by RF energy that can be deployed anywhere within a 25 meter radius and send data to a collector that can relay to the web forever.

VT: Internet of things is the next big revolution, giving us power to actually link anything and everything to the internet. Microcontrollers these days do allow that flexibility to the designers. Freescale’s Kinetis 32-bit microcontroller family is a present example of how microcontrollers allow designers to build and link projects in the Internet of Things.

ST: Yes, there are many manufacturers supplying single chip embedded controller for Internet of Things, where microcontroller, RF and software (IPV4, IPV6 compliant) are offered as a complete solution. More recently, TI has launched – CC2538F512 which is a single chip implementation for the Internet of Things space.

BHO: It certainly allows designers to make their products connected today. For example, microcontroller today has integrated front-end radio frequency circuit for communications. Along with appropriate software stacks, the microcontroller ecosystem allows protocols like Bluetooth or Zigbee to be implemented in a range of applications. Among the applications are Smart Grid or Smart Home for example.

Q. Do you think it is important for designers to consider the availability of software development tools, as a major factor, for the selection of an MCU?
JT: Applications are getting more and more sophisticated, software tools are a key consideration, if not a primary consideration, when selecting an MCU. A recent survey concluded that over 66% of design teams now consist of software engineers. This is reflective of where solutions are needed most. To get applications to market on time and within budget, time must be saved on the software development side.

VT: Software and hardware goes hand-in-hand. Gone are the days when the companies only use to look at the hardware aspect and then customer use to source software on it. Today, companies like us are providing complete solutions to our customers which make it easier for the design engineer.

ST: Yes, it is a key decision factor, as developer do consider a certain architecture on the available software tools & libraries built on that MCU platform. Time to market (development) is a very critical need across the industry and software availability plays a very critical role to address this.

BHO: Yes, it is one major factor that designer should take into consideration when selecting MCU. The design should not be compromised by lack of development tools or the lack of the tool’s features and functions. And the designer themselves, should not be loaded with the burden of tools related problems. At Renesas, we always assure our customers of quality development tools and making sure that they are easily available to them.


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