MCU, MPU Deliver IoT To Auto Industry

Image Source: metamorworks/Shutterstock.com

By Adam Kimmel for Mouser Electronics

Published August 2, 2021

Introduction

The growing connectivity of the modern automobile shouldn’t be a surprise. First, automotive sensors, such as oil pressure, coolant temperature, and fuel level, illuminate warning light icons on the dashboard to alert the driver of an issue. Later, integrated global positioning (GPS) became the earliest smart feature automakers began including in vehicles, with Mazda introducing the first mobile communication system containing GPS in the 1990 Eunos Cosmo. Modern cars also incorporate autonomous features such as automatic parking and lane deviation assist.

Vehicle systems now have over 100 microcontrollers and microprocessors, controlling everything from turning on the headlights to regulating exhaust emissions to how the vehicle interacts with the instrument panel. The following reviews the evolution of sensors, their applications, and how this data has led to software-controlled features increasing our safety, comfort, and connectedness while driving.

MCUs, MPUs Build Bridge Between Vehicle, IoT

Data is the lifeblood of the Internet of Things (IoT). For computers to respond and develop algorithms to improve a device’s performance, engineers must collect massive amounts of data. Sensors surrounding and inside the vehicle gather the data. It is then processed and used to control previously manual features in the car. The processor or controller accepts the data and regresses it to a form that the program algorithm can assess. Then, based on the data it collects, the controller can respond with the appropriate action. Three categories produce the most impactful automotive data: emissions, performance, and passenger comfort.

Automating data transmission from vehicle to external receiver minimized the lag between the vehicle’s signal and response. With this capability, cars can interact with other users, vehicles, or smart cities.

Technology Spectrum of Connected Vehicles

Three primary categories drive automakers to increase sensors’ use: emissions legislation, improved on-road performance, and passenger comfort and safety. These areas define the sensors’ application and provide insight into the emergence of software control.

Emissions Legislation (Powertrain)

After oil, coolant, and fuel measurements, federal emissions regulations compelled automakers to upgrade their sensor technology to monitor combustion performance, leading to emissions output. As a result, engineers developed manifold absolute pressure (MAP) sensors to control the engine’s performance to limit emissions. MAP sensors measure manifold pressure, with which the engine’s control unit calculates air density and mass flow rate.

The combination of these parameters enables automated control of fuel dosing to maximize combustion. In addition, operating as close to stoichiometric combustion chemistry as possible maximizes the extent of the combustion reaction, limiting undesired combustion reaction products that create harmful emissions. A higher degree of reaction and reduced undesired combustion products means that the engine is also operating more efficiently. This condition creates a secondary benefit in that more efficient combustion reduces coking and other unburned hydrocarbon exhaust materials, such as nitrogen oxides (NOx).

Further tightening of automotive emissions regulations, first enacted in the early 1960s, drove automakers’ need to increase the measurement sensitivity and performance of on-vehicle sensors. In response to this need, they adopted microelectromechanical measurement systems sensors (MEMS). These novel sensors, designed for engine control through pressure measurement, quickly expanded throughout the vehicle. Two intertwined factors of MEMS make them adept for engine control: the integration of electronic intelligence with mechanically measured parameters and the small footprint the sensors consume on-vehicle. The marriage of these two factors provides an economical, high-performing solution for data capture and software control. With present-day vehicles manufactured with MEMS that improve engine performance, reduce emissions, increase safety, and add convenience, these sensors continue to gain importance.

Meeting new emissions targets first puts the automaker in a position of strength. Leveraging the data and on-board process/control provides the user the opportunity to reduce the harmful emissions below regulatory targets first, forcing the competition to scramble to catch up.

Improved On-Road Performance (Chassis)

Along with the benefits to powertrain performance, sensors measuring on-road performance at the chassis have advanced. This moment is the point where the features historically linked to vehicular autonomy reside. Examples of these applications include automatic braking systems (ABS), road noise cancellation, traction control, and automated parking. Sensors also measure vibration data for stability control, along with on-wheel tire pressure to prevent a blowout.

Principally, these features center on safety, although a secondary benefit is a smoother driving and riding experience. For example, engineers can use this data to design a more stable frame, optimize tire distances and positions for balance and support, and reduce the stop time by improving the anti-lock braking system (ABS) performance using traditional driving habits. In addition, enhancing the on-road experience is critical to improving the overall driving experience. The IoT can then react to the data the vehicle generates to assure the driver is safe and autonomously move the car to a position out of harm’s way.

Passenger Comfort and Safety (Cabin and Exterior)

The third area that sensors have increased in prevalence is passenger comfort. With the rise of smartphones and connected technology, drivers have become users of the connected interfaces and customizable technology available in their vehicles. With safety at the forefront of the automotive industry, MEMS have improved the deployment patterns and timing of front and side airbags. They also can more accurately predict when to activate headlights in the event of changes in ambient lighting conditions.

Regarding comfort, engineers can use the sensors’ data to remember drivers’ preferences and settings for features such as seat temperature and orientation. Also, sensors can aid in navigation, while driver preferences with the user interface can guide software control preferences. This benefit is likely the most transformative application of MCU/MPU for the passengers.

The Software is in the Driver’s Seat

Implementing MEMS sensors and other technology within the vehicle provides vehicular software engineers the opportunity to tune and optimize the driving experience. Utopia is a robust enough data set that the microprocessing unit (MPU) can receive, analyze, predict, and react to a condition—without the driver needing to employ the control. The challenge has been that internal combustion engines (ICEs) have only limited ability for software-controlled settings. Electrification is the enabler to move toward a substantially software-controlled vehicle environment.

The MPUs and microcontrollers (MCUs), which are located throughout the vehicle, act as the brain to engage the performance, safety, and comfort features drivers and passengers demand from their cars. It is another step toward an autonomous driving experience. With most electric vehicles suited for software control, automakers’ product lines become simpler while providing increased flexibility to their customers. Processing platforms enable software control for the areas listed above. Three use-cases demonstrate the practicality of software-controlled functionality.

Powertrain

System architects select 16-bit digital signal controllers (DSC) and MCUs for an array of ICE and electric vehicle (EV) powertrain applications. A significant benefit of this development is that these platforms provide instant response and high reliability for e-mobility in harsh operating conditions. In addition, they enable software-controlled motor control, exhaust gas recirculation (EGR) valve operation, and water and oil pump control. The 16-bit level equipment, sized for powertrain usage, also facilitates power management, battery charging, and exterior lighting controlled by the vehicle’s software.

Components that are ideal for the software application offer digital signal processing to increase the DSC throughput. Best-in-class DSC and MCUs modulate the pulse width with bidirectional analog/digital converters to maximize speed and performance in both directions.

Chassis

On-road applications such as advanced driver-assist and ABS need access to higher amounts of memory to run the process. Thirty-two-bit solutions can access substantially more memory than 16-bit and often operate at a higher voltage to widen their applicability range. Despite their higher capacity, the 32-bit controllers are still compact enough for automotive while providing the on-road use-cases’ performance.

Cabin and Exterior

For the most complex, innovative, and modern software-controlled car features, a 32-bit MPU is the best choice for a robust design platform. This solution handles infotainment and driver-vehicle interface. With processing power on par with a full computer, the 32-bit MPU analyzes the vast amounts of data that the vehicle computer uses to process high memory-consuming applications and guards against cyber threats with advanced security features.

In addition to providing the cabin and exterior applications’ capacity, the 32-bit MPU also contains security features for data integrity. Furthermore, market-leading MPUs offer embedded audio and video elements to enrich the user experience. These features improve the system’s data processing accuracy, which increases the effectiveness of the software’s prescribed response.

Takeaway

The IoT is encouraging data generation at an unprecedented rate. Processors collect, organize, and act on the data to enable software and autonomous features that improve the vehicle’s carbon footprint, safety, and performance.

MCUs and MPUs are already prevalent in our cars. However, as EVs gain more prominence, solutions such as the 16- and 32-bit MCU and 32-bit MPU are poised to deliver a software-controlled reality. When designers use these components to help process the vast amount of sensor data, they can leverage existing processing infrastructure to set the stage for software-controlled cars to propel the autonomous movement.