Cranes Varsity Blog

Sensors: 

  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. 

Introduction:

          Linux is popular because, it is available for free of cost, so it was liked by the students, the developers can access and modify the source code due to its open source nature, so it was liked by the programmers, it is having the ability to communicate with other different operating systems, so it was liked by the system administrators, and many more to put on.., but there is a potential threat w.r.t. LINUX kernel because of its open source nature. Any hacker can easily understand the kernel architecture and thereby he can find and exploit the loop holes in the operating system and can steal the data easily. So, we will mainly concentrate on the types of attacks that can allow you to hack the Linux network.

Attacks that can be use to gain access on LINUX network:

  1. WORM ATTACKS
  2. TROJAN HORSE
  3. PROGRAM CODE EXPLOITS
  4. MIS CONFIGURED SERVICES
  5. SCANNING
  6. LOCAL HACKING
  7. MAN IN THE MIDDLE ATTACKS
  8. DOS ATTACKS
  9. SPOOFING

Security measures to be taken care of:

        LINUX or any other operating systems are not secure straight out of the box, but we can suggest you the minimum necessary precautions to be taken to avoid getting hacked by the attackers

  • To fix many of the unknown security vulnerabilities, regularly install the patches found at, http://www.linuxsecurity.com
  • Configure your system according to usage.
    1. Always disable a service you don’t need.
    2. Don’t allow any unnecessary permission to any software’s.
  • Always use tools like tcpd.
  • Make use of good and strong passwords for all the users who are using the system.
  • Check the following path on daily basis for any irregular activity and hack attempts.
    1. /var/adm/syslog
    2. /var/adm/messages

          Network on chip or network on a chip (NoC or NOC) is a communication subsystem on an integrated circuit (commonly called a "chip"), typically between intellectual property (IP) cores in a system on a chip (SoC). NoCs can span synchronous and asynchronous clock domains or use unclocked asynchronous logic. NoC technology applies networking theory and methods to on-chip communication and brings notable improvements over conventional bus and crossbar interconnections. NoC improves the scalability of SoCs, and the power efficiency of complex SoCs compared to other designs. Several researchers are investigating the possibility of designing NoCs with wireless interconnects. Recently, the design of a wireless NoC based on CMOS Ultra Wideband (UWB) technology was proposed Zhao et al. [1]. In Zhao et al. [1] a wireless Media Access Control (MAC) protocol based on time-multiplexing of ultra-short pulses from the UWB transceivers was proposed to enable concurrent use of the wireless channels. A wireless NoC with unequal RF transceivers is proposed in Zhao et al. [2] to improve the performance in a conventional mesh topology overlaid with wireless interconnects. In Lee et al. [3] the design of on-chip wireless communication network with miniature antennas and simple transceivers that operate at the sub-THz range of 100–500 GHz has been proposed. Design of a wireless NoC using the small-world topology using carbon nanotube (CNT) antennas operating in the THz frequency range is also presented by various researchers. Due to the possibility of tuning CNT antennas to various frequencies it was possible to communicate using Frequency Division Multiplexing (FDM) on non-overlapping channels. However, challenges of fabrication and integration of CNT antennas with CMOS processes may hinder its adoption in the near future. In Deb et al. [4] design of a wireless NoC with CMOS compatible mm-wave transceivers was proposed. The access to transfer data over the wireless channel was shared between multiple transmitters using a token passing mechanism. This granted access of the wireless medium to only one transmitter at a time. In Wang et al. [5] digital implementations of a CDMA-based wireline NoC were proposed.

However, both these CDMA based NoCs have centralized controllers that allocate codes to the transceivers and add the encoded CDMA bits (chips) prior to sending over the NoC fabric. Such centralized control schemes are not suitable for the distributed MAC protocol desired in the Wireless NoC.

REFERENCES  

[1] D. Zhao, Y. Wang, J. Li, and T. Kikkawa. Design of multi-channel wireless NoC to improve on-chip communication capacity. In Proceedings of the IEEE/ACM International Symposium on Networks-on-Chip. 177–184, 2011

[2] D. Zhao and R. Wu., Overlaid mesh topology design and deadlock free routing in wireless network-on chip. In Proceedings of the IEEE/ACM International Symposium on Networks-on-Chip, 2012

[3] S.-B. Lee, S.-W. Tam, I. Pefkianakis, S. Lu,M. F. Chang, C. Guo, G. Reinman, C. Peng, M. Naik, L. Zhang, and J. Cong. 2009. A scalable micro wireless interconnect structure for CMPs. In Proceedings of the ACM Annual International Conference on Mobile Computing and Networking (MobiCom’09). 20–25.

[4] S. Deb, A. Ganguly, K. Chang, P. P. Pande, B. Beizer, and D. Heo. 2010. Enhancing Performance of Network-on-Chip Architectures with Millimeter-Wave Wireless Interconnects. In Proceedings of the IEEE International Conference on Application-specific Systems Architectures and Processors. 73–80.

[5] X. Wang, A. Tapani, and J. Nurmi. 2007. Applying CDMA technique to network-on-chip. IEEE Trans. VLSI 15, 10, 1091–1100.

[6] Maurizio Palesi, Masoud Daneshtalab, “Routing Algorithms in Networks-on-Chip”, Springer Science & Business Media, 2013

Introduction
There is a lots of difference in embedded systems when compared it with general purpose operating systems. An embedded system is holding a microprocessor which is the heart of the entire system we can say. It will check and control the entire system functionality. The applications of the embedded systems are very huge,we can see the embedded devises in our daily routine life. We are using it in many ways starting from microwave oven to a nuclear reactor.general purpose operating system is for different kind of applications where as embedded system is dedicated to some specific task. The designing of the program in embedded system is taken care by the design engineer, it can not be modified by the end user.
The embedded system has following characteristics which can compete with the other trends.

Reliability:
We are using embedded systems mainly for critical systems, which means we need to get the functionality at the moment when it is needed ,for example: air bag system, it has to operate at the moment when it reaches it’s specific criteria otherwise there is a chances of losing the lives.
Specialized Hardware:
Embedded systems are used for performing real time functions so the hardware what we are using should be secured one. For example,to monitor and analyze the audio signals we will use signal processors.

Cost effective:
Now a days embedded systems are widely used in consumer electronics those are cost effective. The cost of this goods should below.

Robustness or with standing capability:
Even though the environment where the system will work changes, that system has to work properly. We can say that embedded system should be harsh to the environmental conditions, which means it can be
capable for with standing power fluctuations ,vibrations and some excess of heat conditions.

EMBEDDED SOFTWARE DEVELOPMENT
In general application developers, develop their applications for the computers which they are working with. This is not possible in embedded systems due to the usage of limited hardware and software. In embedded systems writing a code,compilation, assembling and linking the program is done on a general purpose computer called as a host machine, which has all required tools for develop the application. Finally the machine code is transferred to the target machine i.e. an embedded system.

The developers need to test the embedded systems by using:
1) Simulator:
It is a software tool,which will run on a host machine and simulates the behaviour of the processor of the target machine and its memory. Simulator knows the instruction set and architecture of the target processor.
2) Emulator:
It is a hardware tool,which needs to test and debug the code on the target machine. In the place of target processor, emulator is connected and it drives the signals into the circuit. All the test conditions will be given to the circuit.

CONCLUSION
The main motto of embedded system is to give a low cost system that is capable of dealing with real time scenario’s by meeting the deadlines. Recent developments in hardware -software co-design permits trade offs between hardware and software for cost effective embedded systems.

Hadoop and Spark are the frameworks used for data processing. Both Hadoop and Spark are maintained by Apache Software Foundation.

Both of these frameworks work on different principles .Hadoop is a common or popular name in the world of  Big Data while Spark is still building a name for itself in a ”style”.

Hadoop:

Hadoop is a Open Source software framework for storing data and running applications on a cluster. It is very useful in Big Data Analytics with great Volume, Velocity, Variety, and Value known as the 4V’s of  Big Data. Data in various forms such as structured, semi-structured and unstructured data.

Hadoop has mainly four core components that work on different essential tasks for Big Data analysis.

  1. Distributed File System : Hadoop has its own distributed file system(HDFS) for storing the data.
  2. Map Reduce : Data store in the HDFS is processed or investigated using map reduce.
  3. YARN : combines central resource manager that manages the node manager agents that monitors the processing of individual clustering nodes.
  4. Hadoop Common : It helps the user read and analyse the collected datain various systems

Hadoop is a great tool when it comes to big data analysis for appilcability, flexibilty, availability.

Spark :

Spark is a framework which provides a number of interconnected platforms systems and standards for big data analysis.

The important difference to be noted between Hadoop and Spark is that spark processes data through logical memory and RAM. While Hadoop works with disks. Spark is pretty much like hadoop as a layer which can load data into memory with parallel analysis.

The major cor components of Spark :

  1. Spark Streaming : The real time data streaming where data is in bulk. It helps you analyze ocean of data.
  2. Spark Core : Distributes tasks and works with scheduling.
  3. Spark Machine Learning Library (MLlib): An extensive library of analytic algorithm for spark cluster, adaptable to all other clusters Spark can work with.

Conclusion on Hadoop, Spark or Both?

When hadoop compared with spark , spark is much speeder than hadoop. Hadoop focuses on transfering data through hard disks ,spark runs its operations through memory. Working through logical RAM  increases the speed. Hence, spark can handle data analysis quite faster than hadoop. But, spark lack with a file system and it hence need hadoop. To get spark work without hadoop one would need to go with the third party file organization system. However, this is complicating and since both hadoop and spark are maintained by Apache Software Foundation it is implied that using spark on top of  hadoop is the best long time solution.

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