Hardware Design Guide for IoT Projects (Part II): Security, FOTA & Regulatory Compliance

In this Part II of the IoT Hardware Design series, our focus will be on other significant design factors such as Security, FOTA , and Compliance Certifications.

Let us dive deep into them!

1. IoT Hardware Design for Security:

   Your IoT project design must include robust security mechanisms to safeguard the IoT system and data, from any unauthorized access and other security threats like IP theft, malware attacks and more.

   Let us look at some of the common hardware security mechanisms in practice today:

   • Root of Trust: A Root of Trust (RoT) is a set of functions (software codes) that are hardened into a hardware module like Hardware Security Module (HSM). This stores the keys to encrypt and decrypt data, and create digital signatures.
   • PUF for Data Security: Data security can be ensured through public and private key mechanism. In order to ensure that these keys are generated from a secure source, you can select hardware devices with a Physically Unclonable Function (PUF).

     Under the PUF scheme, a unique key is generated depending on the unique properties of each piece of silicon.

   • Board level and chip level security measures help to protect the devices against tampering, IP theft, reverse engineering attacks etc.
   • Hardware security against Differential Power Analysis ( DPA) attacks: Often electronic devices are prone to DPA attacks, whereby a hacker can calculate the power consumption of any hardware device to extract cryptographic keys from the device.

     Using hardware devices with DPA licensed countermeasures in your IoT project is a foolproof method to ensure high-end security of your devices.

   
   

   Image Source: iStock

2. FOTA for Remote Device Management:

   In IoT systems, Firmware Over-The-Air (OTA) is a popular technique for remote and reliable management of field devices and applications.

   You can enable Firmware Over-The-Air (OTA) update in IoT devices either by designing  a customized FOTA module from scratch or use any of the managed platform solution for OTA firmware systems

   • In a custom built FOTA solution, you can plan the scheduling, release, recovery, reporting of firmware images; manage the firmware versions; choose the hardware, device interfaces and software for enabling FOTA- based on project requirements and BOM costs..
   • The managed platform based solution comes with in-built hardware , software tools, and takes care of system firmware, device grouping, event logging – among others.

   Also read: The process details of the FOTA update installation onto the target devices.

   

3. Regulatory Compliance & Certifications:

   The rush to meet the functional requirements combined with the pressure for reducing the time to market , most often, leads the project development team to overlook the compliance and certification regulations.

   However innovative your application might be, if it doesn’t meet the certification and compliance regulatory requirements, it is not destined to see the light of day.

   The Product certification and regulatory compliance process must be an integral part of the IoT hardware design phase. You must check that each of the component you pick for your IoT design meets the essential regulatory standards and certifications such as Restriction of Hazardous Substances (RoHS) Directive, Federal Communications Commission’s (FCC) regulations, EMC/EMI compliance – to name a few.

4. Choosing Hardware for Prototype vs Production:

   Selecting hardware for prototype development is altogether different from choosing hardware for production. The objective of the prototype development usually is to demonstrate the most essential and viable functions.

   On the contrary, at the production stage your focus is on factors like future scalability, ease of integration, tolerance to extreme environment conditions, hardware warranty , BOM cost– to name a few.

   A clear definition of prototype and production goals before the IoT hardware design stage will help you make a wise selection of components for IoT sensor nodes and IoT gateway.

   At the prototype stage , you can go for off-the shelf hardware platforms with added features like breadboard-able headers, USB connectivity, onboard antenna.

   For example,  Particle’s Electron is an Arduino-compatible microcontroller with an integrated cellular modem and can be used for faster prototype production.

   And based on the prototype evaluation and business estimates, you can for an off-the shelf hardware boards & components or custom designed ones or have a mix of both.

Hope you liked this blog series on IoT hardware design considerations. If you are looking for a detailed support for IoT project design, contact our product engineering experts.

Hardware Design Guide for IoT Projects (Part I): IoT Sensor Nodes and Gateway Devices

There is no substitute to the ‘in-depth understanding of the business requirements’, if you aspire to deliver a robust hardware design for your next IoT (Internet of Things) Project!

We will allow you some time to imbibe the following words of wisdom from our veteran and highly respected Hardware Design Expert – Mr. Raghavendra (Technical Manager, Embitel Technologies)

He shared with us that before starting with hardware design of an IoT project, he makes sure that the team has all the answers for the following important hardware design considerations:

• What are the physical signals that need to be measured?
• How frequently we need to collect signals and how fast the data should be exchanged over the network?
• Should sensors be connected to the cloud directly or via gateway device?
• How much memory is required?
• And more!

Image Source: Encrypted.com

With this, Raghvendra (known for these no-nonsense talks) nudged us in the right direction for our search for critical hardware design aspects.

This blog can serve as a ‘Hardware Design Guide’ for your IoT (Internet of Things) projects. Read along for more details!

1. Factors Critical to Hardware Design of IoT Sensor Nodes:

   An IoT sensor node consists of sensor device, microcontroller, communication interfaces, power management module and other peripherals

   Let’s discuss the critical hardware design decisions that you may have to take and factors that influence the design:

   • First step is evaluation and selection of an appropriate sensor. Here are the factors/specifications that will have an influence on your decision
     • IoT Sensor resolution: This determines the smallest measurement that a particular type of sensor can reliably detect.

       – Type of sensors required: One can integrate either a digital or analog sensors in the hardware design. If you are using an analog sensor, you must also consider components for signal conditioning and signal processing in your design.

     In such cases, the sensor circuit will also have to include either analogue-to-digital converter (ADC) or Sigma-Delta modulator.

     • Sensor Nodes within an IoT network are expected to transmit 8 to 16 decimals of data in one millionth of second. And choosing a sensor with required data throughput is essential for efficient operations.
   • Microcontrollers: The selection of industrial grade microcontroller is done after a careful evaluation of the business requirement (time and cost of project design) and functional factors that include:
     • Algorithms: A microcontroller uses certain algorithm like ‘Random Number Generation’ algorithm to process sensor data into analog or digital format. So, you need to evaluate the algorithm supported by the particular microcontroller before choosing it.
     • Security: Using a microcontroller with built-in hardware Crypto engines, such as Data Encryption Standard (DIS) and Advanced Encryption Standard (AES) engines, helps to ensure a secure transmission of data from sensor nodes to the IoT network.
     • Power Consumption: Choosing low power microcontrollers helps in optimizing the overall power consumption. One can evaluate microcontrollers specifically designed for ultra-low-power applications, such as TI MSP430 or CC2650 wireless microcontroller.
   • Communication Interfaces: Most of the IoT applications require sensors that use low-power wireless communication modems like NBIoT, LoRA, 4G LTE Cat-M1 for communication.
   • Power management: The sensor nodes are designed to last for years. And this depends on the power source of the sensor nodes. One can choose low power batteries such as CR2032 lithium-ion coin-cell battery, as it outputs a constant voltage, is low-cost and offers a battery life of greater than 10 years.

   Additionally, one may integrate nano-timer such as TPL5110 to optimize the power consumption, as the sensor nodes switch between wake-up and sleep modes.
   

   Image: IoT sensors used today are numerous in types ; Source:IoTOne

   You may read about some common type of sensors – IR sensors, proximity sensors, used in industrial automation systems here in detail.

I

Hardware Related Factors that influence your IoT Gateway Design:

An IoT gateway could either be a simple gateway device that executes core  functions such as protocol compatibility and device management; or an Advanced edge gateway devices with additional data analytical capabilities.

Designing an IoT gateway hardware would thus depend largely on the type of functions it is expected to perform.

Here is a glimpse of some common hardware design parameters that will influence your IoT gateway development

• Microcontoller v/s Microprocessor: An IoT Gateway with microcontroller is ideal for small to a medium scale application, while you may need a gateway with a processor, if the gateway has to perform more complex functions such as data analysis and storage.
• Power Consumption: This will depend on the complexity of your IoT hardware & power requirements of other components of the circuit. For example, if your design consist of a number of external devices such as display screens, camera – the overall power consumption might go up.
• Energy from renewable sources: If your device is being powered by renewable energy sources like solar, your design will have additional components. For example, you would need as 2 stage solar converters ( MPPT based converters and DC –DC/DC-AC converters), power management ICs that are compatible to the solar panels to sufficiently charge your devices.
• Processing Power & OS: This becomes a critical factor if you are deploying Gateway with Edge Analytics capabilities. This is because for data processing, IoT Gateway design should include necessary amount of  memory, and a multi-core processor. The OS chosen should have a higher context switching rate and real-time response rate.
• Memory : Most of the gateway devices used in critical IoT systems such industrial automation, fleet management are based on hard real-time controllers and hard real-time schedulers. In such cases , data is stored in RAM memory. Other memory types used in a smart IoT gateway device would include NOR Flash, Flash boot .

As mentioned before, the memory requirement in the design increases, if the IoT gateway device is expected to perform processing and data analytics.

• Communication/ Networking Modules:
  Within an IoT network, devices or systems ( sensor, gateway, end devices) can communicate either through a Wireless ( Bluetooth, Wi-Fi, Cellular) communication channel or  a Wired Connection.

  Your IoT design will have to include Wireless communication modules when when the devices/systems are located in close proximity and there is little scope for setting up hardware installations required by a wired connection. (installing Ethernet cables, routers etc.) .

   

  Communication Interface	Type of Wireless Communication
  Sensor/Device to Gateway	Cellular(4G), NBIoT, ZigBee, Bluetooth
  Device to Cloud	WiFi, Cellular(4G), 6LowPan, LoRa

  
  A wired communication is usually deployed for long range communications. Ethernet, with an average speed of 10 Mbps, is one of the most used wired communication protocol for connecting devices for applications like industrial automation.

  Fast Ethernet (IEEE 802.3u) and Gigabit Ethernet(IEEE 802.3z) with transmission speeds of 100Mbps and 1000Mbps are some of the widely deployed wired connection interfaces.

  Many of the standard IoT hardware boards such as Raspberry Pi, Arduino, Beagle Bone are embedded with a set of communication interfaces ( UART, USB, Bluetooth ,  Wi-Fi, Ethernet port). You can also create a custom hardware board wherein you include only the selected communication interfaces that your project needs.

Hope you liked this blog. If you are looking for a more detailed and personalized support for IoT project design, please get in touch with our product engineering experts.

Challenges your Automotive Team may Confront During Migration from CAN 2.0 to CAN FD

Imagine a scenario where a car driving on a slippery road loses traction and starts to skid. In such an emergency situation, the built-in Electronic Stability Program is required to get into the action.

This program will need to detect the vehicle speed and the torque on each wheel, at real-time, to take corrective measures.

CAN 2.0 protocol, with its 8-bit data rate and lesser payload capacity, may not be the best solution for such applications.

For such data-intensive applications that call for faster response times, CAN FD (Flexible Data Rate), a successor of CAN 2.0 protocol, has been developed.

In the era of ADAS, Remote Diagnostics and other connected car applications, the need for migration to CAN FD is being felt by technology teams across the globe.

This transition has its own set of challenges, which we will discuss in detail.

So before kick-starting your CAN FD migration project, do read about these personal experiences of our Automotive Product Engineering Services team.

Migration of Existing Application from Classical CAN to CAN FD

Before we start to explain this scenario, it is important to highlight the architectural difference between CAN 2.0 and CAN FD.

The increase in data transfer rate and payload capacity in CAN FD is brought about by the change in the data link layer and the physical layer. The CAN messages that had to be split because of 8 byte payload limitation in CAN 2.0, can be combined into one message in CAN FD protocol.

Major Differences in CAN 2.0 and CAN FD

For an application to be migrated to CAN FD from Classical CAN, the data link layer needs to be first made compliant with CAN FD.

The data link layer comprises of the ISO Transport Protocol (TP) layer as well as the CAN FD device drivers.

Hence, the migration in this scenario is a 2-step process.

1. ISO Transport Layer Development Based on CAN FD Document

   In case of CAN 2.0, the transport layer can receive or transmit data length in tune of 256*16. However, CAN FD transport layer is capable of receiving/transmitting data length of much larger size i.e. 2^32-1.

   Hence, to support the 64 data bytes payload and CAN FD message frames the automotive software team will have to make relevant changes in the Transport Layer. The changes in the TP layer is made according to the standards mentioned in the CAN FD documents.

2. Developing the CAN FD based drivers for the microcontroller family

   In order for the microcontroller to receive and transmit CAN FD data frames, the CAN FD drivers are written w.r.t the MCU family. The Bit Stream Processor is the component tasked with receiving/transmitting CAN FD frames. Separate drivers are required for each of these components to function.

Need for External CAN FD Controller

At times, there are certain legacy microcontrollers that do not support CAN FD protocol.

One solution is to replace the entire MCU with a CAN FD supported microcontroller. However, changing the entire MCU hardware may not be a viable option. This would mean following the entire process of device driver development, integration and testing. The escalated cost and time-to-market can have a major impact on the ROI.

A better and one of the most widely used methods to make such systems CAN FD compatible is to add an external CAN FD controller. These controllers act as slave devices and communicate with the vehicle network on behalf of the main control unit.

The automotive ECU communicates with an external CAN FD controller using Serial Peripheral Interface (SPI). The communication starts by application asking for some vehicle parameter say engine speed. The transceiver in the MCU will interface with the external CAN FD controller.

The external controller, on the other hand, will act as a CAN FD engine. It will process the CAN messages from the vehicle and pass any relevant information to the MCU.

The role of the automotive software developers here is to develop the SPI based drivers to help the MCU communicate with the external CAN FD controller. Device drivers, as well as, low-level drivers also need to be developed for this slave device.

Mixed Networks and Partial Networking

Mixed networks where both CAN 2.0 and CAN FD nodes exist, on the same network bus, are quite common. Although CAN FD transceivers are compatible with Classical CAN, the data link layer is not.

This implies that if a CAN FD node sends a signal, the CAN 2.0 node will not be able to receive it, causing error and interruption in the communication.

One of the most widely used methods to fix this compatibility issue is partial networking. The partial networking functionality makes use of a CAN transceiver standard, called CAN with selective wake.

When a CAN FD is communicating, the CAN 2.0 nodes are passive i.e. invisible to the network. This condition is akin to putting the CAN 2.0 nodes to sleep while CAN FD communicates. However, the CAN 2.0 nodes are not completely inactive; they are selectively awake.

A Partial Networking (PN) transceiver comes into picture in such a scenario. This transceiver keeps the CAN 2.0 disconnected from the network during CAN FD communication. As soon as a valid CAN 2.0 wake up message appears, the transceiver will wake up the CAN 2.0 nodes and route the message to them. It is interesting to note that this wake up message frame is sent by CAN FD node itself.

“There is a power factor associated with partial networking too. When the CAN 2.0 nodes are made passive, they enter a low-power mode. In electric vehicles, this helps save a fair amount of battery power as well. “

Conclusion

CAN FD not only ensures high speed data transfer but also does it securely. With the emergence of concepts such as telematics, connected cars, and remote ECU reprogramming, security has been a major issue. Also, the update size for certain applications have become larger and frequent.

CAN FD is able to handle both these issues efficiently. And with swift migration of applications to CAN FD, the complete transition from Classical CAN to CAN FD will soon be a reality.

Automotive Motor Control System: The Brain Behind the Brushless DC Motors in an Automotive Application

In any Mechanical or Electronic system, where ever there is a continuous rotational motion involved, there is a Motor. And in the modern-day automotive, where comfort is as important as the driving efficiency, Motors play a pivotal role.

Be it the windows, seats, steering, turbochargers, ventilation flaps or brakes, there are Electric Motors to be found in each of these components. In fact, there are a few hundred electric motors in a passenger car. You see, they are called Motor-Cars for a reason!

The motors, however, don’t start and stop on their own. Like many other automotive components that are controlled by Electronic Control Units (ECU), there are also Motor Control Systems to drive a Motor.

To understand this system in detail, we met our automotive team members, who were more than eager to share their knowledge and insights with us.

While we had a basic understanding of Automotive Motor Controllers, we didn’t have the faintest of idea about how advanced these motor control systems have become. This blog is about sharing these learning with our community of Automotive Developers.

Different Types of Motors you would find in your Automobile

Our conversation with the Automotive Team began by discussing the various types of electric motors deployed in modern-day cars

During this discussion, we realized that Electric Motors have come a long way, as far as their applications in automotive industry are concerned. And this evolution is still on-going.

Many safety as well as comforting features in a vehicle, require Electric Motors. Depending on the applications, there are primarily 3 types of motors that are widely used in the vehicles:

1. Brushed DC Motors: These DC motors have metallic brushes between the motor coils and the rotors that complete the circuit. There is no electronic component required to operate this motor. They are ideal motors for Power Window, Seating Control, and other such applications where mechanical parts are operated without any assistance of an electronic systems (like an MCU or a drive logic).
2. Brushless DC Motors: These are one of the most widely used DC Motors. A brushless DC motor has permanent magnets as the rotors. As the current is passed through the motor coils (stator), the rotor being a permanent magnet starts to rotate. As there is no physical contact between the stator and rotor, a motor controller is required to alter the speed of the BLDC motor.
3. AC Induction Motor: Most widely used in Electric Vehicle Drivetrain applications, an AC Induction Motor works on the principles of Faraday’s law of induction. There is a rotating magnetic field produced due to the alternating current in the coils. This moves the rotor. The speed of the motor can be altered by varying the frequency of the alternating current supplied to the motor.

Understanding the Anatomy of an Automotive Motor Control System

Business use-cases and applications of Electic Motors in automotive, called for systems which can control the motor according to the application-specific logic. For instance, a motor deployed in an Electronic Power Steering (EPS) system is required to alter its speed based on the torque applied by the driver on the steering wheel.

A motor control system is required to implement this logic.

This system is essentially an Electronic Control Unit (ECU) like all other ECUs in a vehicle. It comprises of a Microcontroller ported with the Motor Drive Logic (software) and integrated with some other Motor-Control peripherals (hardware).

The Motor Drive Logic is the software algorithm that drives the motor in the intended manner. The peripherals like gate driver IC, MOSFETS etc. are part of the control system that performs auxiliary tasks like error feedback handling, signal conditioning, current and voltage amplification. We will learn more in detail about all these components, very soon!

We were also introduced to how a Motor Control System works. But before we get started with this,.

Let’s first learn about the components of a Motor control system:

1. Microcontroller: Microcontroller Unit (MCU) is essentially the component where the Motor Drive Logic is stored.

   For instance, in an electronic power steering application, a steering control algorithm will be stored in a microcontroller platform. The algorithm is used to vary the speed of the motor using Pulse Width Modulation (PWM) signals.

   Input and Output buttons can be interfaced with this MCU. PWM signal which is generated as the output and is interfaced with the next core component of the Motor Control System.

2. Gate Driver IC: Gate Driver IC also known as a pre-driver is that next core component! It, receives the PWM signal from the MCU and amplifies it to make it suitable for the MOSFET.

   This was a little confusing for us because knowing that MOSFETs are generally used to amplify the voltage, then what is the purpose of having a Gate Driver IC in a motor control system.

   We were informed that there is a certain threshold voltage value that is required by a MOSFET to be able to function; Gate driver IC provides that threshold voltage. Also, there are some signal conditioning algorithms in the Gate driver IC that removes the noise from the signal and smoothens it.

3. MOSFETs: These are field effect transistors that can amplify a few milliamps current to ten times and small voltage value to several hundred volts. As electric motors require minimal switching time in varying the current flow to the motor, MOSFETs are an indispensable part of the Motor Control System.
4. Hall Effect Sensors: The role of Hall Effect sensors in automotive motor control application is to determine the position of the motor. It is essentially a transducer that will induce a voltage when the flowing charge comes under the effect of a permanent magnet.

   Hall sensors are fitted to the rotor so that its position is known before the motor coils are energized.

   The following diagram shows the different components of a motor control system
   

   
   A Typical Automotive Motor Control System with a 3-phase BLDC Motor

How a Motor Control System Works?

The signal to start or stop an electric motor comes from the microcontroller. Unlike a brushed DC motor, where there are brushes to complete the motor circuit, BLDC motors use Hall-effect sensors to energize the motor coils.

The microcontroller uses the input from Hall-effect sensor to determine the position of the rotor. Based on the position, it will energize the motor coils thus creating a rotating electrical field. This field will move the rotor along with it.

This is the physics and mechanics behind the motor movement.

Post this, we discussed the electronics behind the motor control system and the role of MCU and the gate drivers.

The Microcontroller unit is ported with the motor drive logic, Pulse Width Modulation module and other algorithms depending on the application. Based on the logic, the PWM signals will be relayed from the MCU. The Hall-effect sensor will determine the exact moment when the PWM signal should be sent to the motor.

For example, if the BLDC is deployed in an electronic power steering, the MCU will have steering control/assist algorithms and PWM signal will be produced according to that logic. The timing will still be controlled by the Hall-effect sensor.

While the microcontroller unit gives the BLDC motor a start, there are other components required to keep it running. They are the gate driver IC or the MOSFETs. Power control and motor drive are two things that the MOSFETs and gate driver unit are tasked with.

As mentioned earlier, MOSFETs can amplify current and voltage to fairly high levels. However, at times, a gate driver IC is also required to condition the signal going to the MOSFET. The gate driver IC or the pre-driver IC is a kind of pre-amplifier that filters out the noise in the signal before it is fed to the MOSFET and eventually to the BLDC motor.

In most automotive motor control applications, these MOSFETs are structured in an H-bridge configuration where they control the current flow path to the motor coils. This ensures full control of the speed and direction of the BLDC motor.

Now that the working of a motor control system is clear, let’s look at some of their applications in the area of automotive:

Some Common Applications of Motors in Vehicles:

• Electronic Power Steering-A BLDC motor works with a MCU with steering control algorithm, PWM, current loop PI etc.
• Seating Control: Electronically adjustable seats are also driven by electric motors. Some advanced algorithms in the motor control system ensure that there is no jerk or sudden start/stop in the seat. It is called soft stop/start.
• Electric Vehicles Drivetrain: Most electric vehicles deploy an AC induction motor in their drive train. A three-phase AC power input is given to the motor that produces rotating magnetic field. By altering the frequency of the AC power supply, the speed of the wheel can be adjusted.

Concluding Thoughts

The combination of mechanics and electronics has led to various advancements in automotive motor control system. A simple brushless DC motor is now being deployed to make some smart moves as it is driven by motor drive logic.

If you drive a modern car, you must have noticed how smooth the power steering, power window and seat adjustment etc. has become. All this has been possible with advanced motor control system that not only drive a motor in different speeds and directions, but also in an efficient and smooth manner.

However, the most prominent role of electric motors can be witnessed in electric vehicles that are virtually run by motors, both DC and AC. Electric Vehicle pioneers like Tesla etc. are investing heavily on motor control system that can get maximum output from motors with the least input.