Meet the Needs of Modern Sensing Applications With Low-Power and Highly Integrated MCUs and Sensors

Modern Sensing

Abstract

With the evolution of the Internet of Things (IoT), sensors are proliferating throughout commercial and industrial environments. The diverse applications of these sensors often only allow for low-power operation with sensor devices, and can be powered with low-cost renewable energy, energy harvesting systems, or battery power. Moreover, this new wave of intelligent applications requires sensors in almost every environment with unique power and communication requirements. Microchip has built a comprehensive portfolio of Microcontrollers (MCUs) with precision integrated analog capabilities, diverse interface and communication options, and industry-leading low-power operation, as well as an extensive line of sensor solutions compatible with modern MCUs.

Predicting the Needs of IoT

There are several predictions that the number of IoT devices will raise from more than 20 billion to almost 80 billion devices by 2025[1]. Many of these IoT devices have one—or multiple—sensors, and there are also a large number of sensor devices not connected to the internet. One of the predominant roles of IoT devices is to acquire, analyze, and report sensor data about the environment around them. This is made possible with sensors and MCUs to digitize, process, and handle communication of the sensor data. 

The modern use of sensors differs from the past where sensor recorders may have only reported at threshold moments, or when data was acquired over long periods of time. It is not uncommon for today’s sensors to capture data continuously, and at high rates, while communicating the sensor data to large cloud servers that support diverse applications. It is also now standard for the density and variety of sensors distributed throughout an environment to far exceed the number of sensor devices of a few years ago. 

Hence, the modern requirements of sensors involve challenges that previous generations of sensor designers didn’t face. Moreover, these challenges require highly integrated MCU solutions to provide power, performance, and select features.

Modern Sensor Challenges

Some of the most significant concerns for sensor applications are meeting a low-power requirement while optimizing performance. Generally, power and performance are proportional, and for greater performance more power is needed. This is a challenge for many sensor applications running on small amounts of AC, DC, renewable energy, or battery power. In the case of renewable energy and battery power, extending battery life while still meeting all sensor, processing, and communication requirements is vital. Frequently, the cost of replacing or charging a battery powered sensor could exceed the cost of merely replacing the sensor unit, making ultra-low-power sensor devices extremely attractive for IoT applications.

Another challenge with the number of sensors distributed throughout the environment is enabling communications connectivity or internet connectivity for IoT devices. Running hardline Ethernet or data cables to multitudes of sensors distributed throughout an environment could be costly, or even unfeasible, for many applications. However, some high-bandwidth sensor applications may need the security, resilience, and speed of hardline data cables, such as with security video and sensors. Hence, sensor connectivity options that include wired and/or wireless capability is critical in efficiently deploying sensor systems. 

There are many opportunities and benefits from sensor synergy-leveraging cloud services, which intelligently enhance the value of sensor data by using machine learning and algorithms during data analysis. Enabling cloud functions for a distributed sensor requires sophisticated connectivity and a software platform. It also opens a variety of security concerns beyond that typically associated with connected sensors. The dangers of tampering, spoofing, hijacking, or otherwise hacking connected sensor devices is also a growing concern as systems become more automated and dependent on connected sensor data. Some applications may require secure communications as well as secure protection of the sensor data, compounding the challenge of developing adequate security measures.

Ensuring environmental stability and calibrated sensor data is an age-old difficulty in environments with extreme temperatures and other harsh conditions. Moreover, many MCUs, sensor and data processing, communications circuits and peripherals aren’t designed to operate in extreme environments. Without a wide operating temperature range, the information from a connected sensor could lose accuracy and ultimately become unusable. This is unless each component and circuit in the sensor, processing, and communication is capable of streamlined operation throughout the environmental requirements.

How Highly Efficient MCUs and a Wealth of Options Enable Sensor Applications

Meeting the challenges listed in the prior section, while keeping MCU and sensor costs low and sensor footprint small, enhances the burden on designers and developers of sensor applications. Microchip has designed several MCU families, along with a variety of sensors, development boards, and tools, to address these challenges. The features built-in to Microchip MCUs are well-suited to sensor applications, including:

• eXtreme Low Power (XLP) operation 
• Intelligent on-chip peripherals• Secure data transfer with a cryptographic engine and key storage
• Highly integrated analog peripherals
• Compatibility with modern analog and digital signals commonly used for sensor communications

Extremely Low Power Operation and Core Independent Peripherals Extend Battery Life

Acknowledging the need for extended battery life, Microchip has further developed its MCU’s low power capability with several internal standards called eXtreme Low-Power (XLP) specifications. The internal XLP specification features low sleep and operational power consumption. These include sleep currents down to 9 nA, a real-time clock down to 300 nA, and a Watchdog Timer (WDT) down to 200 nA. The XLP MCUs also offer energy-saving features such as automatic switch-over on Vdd loss, a Real-Time Clock/Calendar (RTCC), and the ability to be powered separately from a 1.8 to 3.6V backup source. 

The portfolio of XLP MCUs is also sizable enough to offer performance and features to match the needs of many low-power applications. These MCUs range from 8- to 121-pins, 4 KB to 1 MB Flash memory and a wide selection of package sizes and types. They are also designed with active mode currents as low as 30 μA/MHz along with highly efficient instruction sets with over 90% single-cycle instructions. Many of these MCUs are available in QFN, uQFN, and chip-scale packages with reduced footprints for space-constrained designs. 

Furthermore, several Microchip MCUs are equipped with Core Independent Peripherals (CIPs) that allow for these peripherals to operate without the need to turn-on or run the main MCU core. The CIPs along with other highly integrated peripherals reduce energy use and decrease development time. XLP MCU CIPs include op amps, LCD drivers, USB, capacitive touch sensing, DMA and cryptography modules. Therefore, these MCUs use much less processing power during normal operation of peripherals and further extend low-power operation. 

Connectivity Diversity Benefits Sensors

Many 8-bit and 16-bit MCUs are limited in their analog and digital communication capability. This seriously hampers sensor development, as the various types of sensors present diverse interface and communication requirements. For instance, some modern accelerometers may require several digital signal channels, or a fast serial interface, while an older style motion detection sensor may require precision analog conversion and comparison. Hence, Microchip MCUs often include several types of integrated Analog-to-Digital Converters (ADCs), operational amplifiers (op-amps), analog comparators, and Digital-to-Analog Converters (DACs) for enhanced signal conditioning. 

Sensors Options Simplify Designs

Though external sensors enable a wide range of applications, there are several primary sensors that, if integrated, can reduce BOM, footprint, save power, reduce noise, and increase reliability. These sensors include local temperature and capacitive touch controllers. Many Microchip MCUs feature integrated temperature and touch controllers, which eliminates the need for common external components. 

In the case where a variety of sensors are needed, Microchip also offers many other sensors, such as humidity, proximity, weather, temperature, acceleration, position, air quality, alcohol, CO, differential pressure, current, heart rate, gyroscopic, methane, LPG, hydrogen, and compass sensing. Most of these sensors use digital signal connectivity and self-calibrate, removing the need for additional hardware design and development time calibrating sensors from the analog input. 

To further ease development, Microchip offers many of these sensor types as MikroElektronika Click boards™. These are compatible with the included Click board interfaces on Microchip’s Curiosity and Explorer Development Boards. These development boards, code examples, and software libraries for sensor applications reduce the burden of experimenting and prototyping with sensor types, applications, and speed development time. 

Conclusion

The wealth of opportunities to benefit virtually all markets with enhanced sensor use is mind-boggling. Entire new branches of industries have emerged in the last several years due to the cost and size of sensors dropping below a critical threshold. From medical sensing, smart metering/smart grid, to the expanses of the Internet of Things, low-cost and small form-factor sensors and MCUs are vital enablers of intelligent systems that create safer, secure, and more efficient systems.

However, the growing precision, performance, and communication requirements of the sensors able to facilitate these new applications place additional burdens on sensor designers and developers. Microchip offers MCUs, sensors, and development tools that allow for lower-cost sensor modules in smaller footprints, and eases development costs with richly featured development boards compatible with modular sensor boards.