Cranes Varsity Blog

 The Flex-Ray networking standard for motor vehicles provides a foundation that will shape the control structures of automotive electronic for many years to come. Flex-Ray serves as the next step beyond CAN and LIN, enabling the reliable management of many more safety and comfort features. Flex-Ray suits X-by-Wire applications.

 Flex-Ray focuses on a set of core needs for today’s automotive industry, includes higher data rates than previous standards, flexible data communications, versatile topology options, and fault-tolerant operation. Flex-Ray thus delivers the speed and reliability required for next-generation in-car control systems.The CAN network has reached its performance limits with a maximum speed of 1 Mbps. With a maximum data rate of 10 Mbps available on two channels, giving a gross data rate of up to 20Mbit/sec, Flex-Ray potentially offers 20 times higher net bandwidth than CAN when used in the same application.

 Flex-Ray also offers many reliability features not available in CAN. Specifically, a redundant communication capability enables fully duplicated network configurations and schedule monitoring by hardware. Flex-Ray also offers flexible configurations, with support for topologies such as bus, star, and hybrid types. Designers can configure distributed systems by combining two or more of these topologies. Moreover, Flex-Ray allows both synchronous (real-time) and asynchronous data transfer to meet the demand for various systems in vehicles. For example, a distributed control system usually requires synchronous data transmission.

 To meet diverse communication requirements, Flex-Ray also provides both static and dynamic communication segments within each communication cycle. The static communication segment provides bounded latency, and the dynamic segment helps meet varying bandwidth requirements that can emerge at system run time. The fixed-length static segment of a Flex-Ray frame transfers messages with a fixed-time-trigger method, and the dynamic segment transfers messages with a flexible, time-trigger method. In addition to operating as a single-channel system like CAN and LIN, Flex-Ray can operate as a dual-channel system. The dual-channel option makes data available via a redundant network a vital capability for a high-reliability system. Flex-Ray’s characteristics suit real-time control functions. Flex-Ray offers the highest reliability among the protocols. Further compares networking standards by node cost and data rate.

Globally, Wi-Fi has been used for years to access and transmit data. But more often than not, Wi-Fi and their modems have elicited unsavoury remarks when more users have logged on. 

 Li-Fi is now poised to transform for the better the scenario of data transfer and access.

What is Li-Fi???

  • Li-Fi is a bidirectional, high-speed, fully-networked wireless communications technology. 
  • In simple words, it can be considered a light-based Wi-Fi. Where radio waves are deployed to transmit data and information in Wi-Fi, Li-Fi uses light waves, which is faster and acts as a better tool for communication.
  • In Li-Fi, LED lamps fitted with transceivers can light a room and receive information too. 
  • Unlike Wi-Fi, which can hold limited access points only, Li-Fi can have multiple. 
  • Considered a Visible Light Communications (VLC) system that runs wireless communications at extremely high speeds, Li-Wi uses common household LED (light-emitting diode) bulbs to transfer data, ensuring speeds of up to 224 gigabits per second.

How Li-Fi is generated??

  1. A LED bulb is a semiconductor light source. 
  2. Consequently, the constant current of electricity supplied to a LED bulb can be dimmed and dipped up and down at very high speeds without being detected by the human eye. 
  3. For instance, data can be fed into a LED light bulb via signal-processing technology.
  4. Thereafter, this data is embedded in its beam and sent back at rapid speeds to the photo-detector or photodiode. 5. Miniscule changes in the LED bulb’s swift dimming are converted by the receiver into electrical signals. 
  5. Finally, the signal is reconverted into a binary data stream recognisable as web, video or audio applications running on Internet-enabled devices.

The spectrum of visible light is considered 10,000 times bigger than that of radio waves on the electromagnetic spectrum, which measures radiation frequency. Deploying light can avoid the expenses required for the limited range of radio waves.

The embedded industry was born with the invention of micro controllers/microprocessors and since then it has evolved into various forms, from primarily being designed for machine control applications to various other new verticals with the convergence of data communications. 

Various classes of embedded systems such as media systems for homes, portable players, smart phones, embedded medical devices and sensors, automotive embedded systems have surrounded us and with continued convergence of data communications and computing functions within these devices, embedded systems are transforming themselves into really complex systems,  thus creating newer opportunities and challenges to develop and market more powerful, energy efficient processors, peripherals and other accessories.

An embedded system is more than the electronics as most people perceive it. It has electronics – both digital and analog, special purpose sensors and actuators, software, mechanical items etc., and with design challenges of space, weight, speed, cost and power consumption. Its important characteristics are low-power, real-time responsiveness, low thermal dissipation, predictable,small physical form factor/footprint, low radiation/emission, ruggedness in design and impervious to external radiations etc.

In order to achieve key requirements, generally embedded systems are restricted to limited resources in terms of computing, memory, display size etc. With continued convergence of other technologies a lot more functionalities are being pushed into embedded devices which were once part of traditional computing platforms. This further adds a major “decision challenge” for architects and product managers on selection of processors, operating systems, standards of usage etc., as demands on functionality increase with time to market decreases. 

Automotive Embedded System

With drive across the world to improve on emission controls and bring in efficiency in usage of fossil fuels, the automotive segment is challenged by various factors and embedded systems are clearly the ways and means of achieving multiple objectives in this segment taking it from infotainment systems, engine control unit, Car-area-network, fuel management, safety systems all need embedded to be in it. 

Traffic management and prediction systems are being developed for large cities across the world today and the critical systems that has to support this is M2M or V2V communication networks that, form adhoc networks, seamlessly gather information from multiple sources, fuse and make decision that not only help the car users but also city traffic managers.  

The realtime management of this is possible only by having embedded computing and communication systems that are part of the vehicle and the network.  The usage of vehicle tracking and fleet tracking has already been beneficial for the operators by reducing their opex and downtime which has enhanced the customer satisfaction. 

This apart, media oriented systems transport (MOST) is one of the technologies being deployed by OEMs for multimedia and infotainment networking. This technology is designed to provide an efficient and cost-effective fabric to transmit audio, video, data and control information between devices attached even to the harsh environment of an automobile.


MOST (Media Oriented Systems Transport) is a high-speed multimedia network technology optimized by the automotive industry. It can be used for applications inside or outside the car. The serial MOST bus uses a daisy-chain topology or ring topology and synchronous data communication to transport audio, video, voice and data signals via plastic optical fiber (POF) (MOST25, MOST150) or electrical conductor (MOST50, MOST150) physical layers.

MOST technology is used in almost every car brand worldwide, including AudiBMWGeneral MotorsHyundaiJaguar,LanciaLand RoverMercedes-BenzPorscheToyotaVolkswagenSAABSKODASEAT and Volvo. SMSC and MOST are registered trademarks of Standard Micro systems Corporation (“SMSC”), now owned by Microchip Technology.

The first multimedia installation based on MOST bus and protocol was introduced in the year 2001. In the same year, MOST bus was applied in the next ten vehicle models. In the year 2013, MOST Cooperation consortium could report MOST introduction into 140 vehicle models including new models i.e. Audi A3 and Mercedes class S. MOST bus and protocol have been present in popular medium segment vehicles e.g. Volkswagen Golf and Opel Insignia as well as the models: Rolls Royce Ghost, Phantom and Wraith. The functioning of majority of wire communication buses in motor vehicles is based on linear bus topology. Therefore MOST bus is a unique solution because it is based on ring topology (Fig. 1). The application of fiber optic solution is another specific feature. The communication via cable connections is possible after transceivers replacement.

MOST bus operation is typical for ring topology. The data block received from preceding node is used as information and commands source. The block received from preceding node is regenerated and forwarded. Turned off devices transmit optical signal without its analysis. The data transfer is finished when the block is received by its sender. The ring contains some special nodes responsible for the ring management i.e. commands generation on the basis of user activity and for the ring synchronization (Fig. 1b). MOST protocol and bus are dedicated to multimedia networks which are sometimes called Infotainment networks. High throughput levels are required for data stream in such networks. Despite MOST150 standard functioning since several years, this fact has been not mentioned in many publications. Most often the graphical presentations inform about the throughput of about 25 Mbps (Fig. 2)which is underestimated by three times.  The throughput of 150 Mbps will be probably exceeded soon. The manufacturers of Plastic Optical Fibers (POF) indicate the through puts of 500 Mbps along the section of 20 m or 170 Mbps along the section of 115 m. The transceiving equipment is prepared for operation with throughput of 5 Gbps. The current throughput is sufficient to use MOST as an element in the network supporting images received from security camera or from the games network.


You are working on a new design and want to choose an ARM based processor. The questions at this point could be:

 How do I choose ARM based processors?

 What ARM based processor options are available in the market?

 How do I procure ARM based processors?

 What are the different variants of ARM based processors?


ARM is a fabless company. This means that ARM does not manufacture silicon. ARM designs processor cores and licenses them to its silicon partners. The silicon partners, in turn, design microprocessors / microcontrollers around these cores and manufacture the actual silicon or chips available for commercial purchase in the market.

In case you are keen to know more about the ARM Cores than the silicon variants of the processors available in the market, you may refer to the Processor Overview section ARM’s website. This section provides a lot of information on ARM processor families, the architecture, features, reference methodologies, etc. which would a good starting point. If you wish to see more detailed documents on ARM cores, you may also refer to InfoCenter - the documentation section on ARM website.

Choosing an ARM based processors may involve lot of technical and non-technical considerations. A partial list could look something like this:


  • Electrical charateristics - power, frequency, etc.
  • Processing performance - MIPS, DMIPS, etc.
  • Functional domain - Application, Realtime, Microcontroller
  • Instruction Set - regular, DSP, SIMD, etc.
  • Internal features - Caches, TCMs, MPU/MMU, etc.
  • External Features - IO lines, Communication protocols, Interrupt lines, etc.
  • Development tools - software, hardware, etc.


  • Support
  • Maintenance
  • Development Tools support & maintenance
  • Economic feasibility
  • End product lifespan
  • Third-world acceptance and compatibility (tools, applications, etc.)


  The intrinsic part of embedded system are sensors . Right from simple tv remote to security systems installed at home. They are also becoming important for weather stations to forecast weather parameters(temperature, wind speed, wind direction, solar radiation, and many more) and in IoT(to gather data, sharing data etc) .

Definition and Working of Sensors?

  Sensor is a module or a chip that frequently used to detect the changes happening in the (electrical or optical signals) and revert back to the controller or processor (i.e micro controller or microprocessor). i.e sensor converts the physical parameters (like temperature, distance etc ) to measurable electrical signal. For smooth working of sensor a proper power supply and grounding to be provided.

Classification of Sensors

  Depending on the type of sensors the controller accepts two types of input

  1. Analog
  2. Digital

Analog sensor 

  1. This type of sensor senses the superficial parameters (like speed of air, radiations, intensity of light etc.) and gives analog voltage as an output. 
  2. The output voltage may be in the range of 0 to 5V. 
  3. Logic High is treated as “1” (3.5 to 5V) 
  4. Logic Low is indicated by “0” (0 to 3.5 V).

Digital Sensors: 

  Analog sensors produce a analog voltage as the output, whereas Digital sensors produce a discrete values(0’s-OFF and 1’s-ON) .  Where 0 is low voltage(OFF) and 1 is high voltage(ON). These values are called as digital (binary) signals.

  • Analog sensors are made up of analog components like resistor, capacitor, Operational amplifiers, diodes and transistors.
  • Digital sensors consist of logic gates and micro controller chips. 
  • Analog signals are much affected by external noise and create errors in the output signal. But digital signals are capable to noisy surroundings and hence digital sensors are preferred over analog ones.

Cons  with digital sensors:

  Digital sensors have low calculation range. For ex: some digital temperature sensor series like HYT217 AND SHT have lower range of temperature measurement. But analog temperature sensors (RTD) have higher step size (+ve and -ve temperature). This feature makes analog sensors suitable for wide temperature range and stability.