Consistent Overhead Byte Stuffing
Byte stuffing is a process that transforms a sequence of data bytes that may contain ‘illegal’ or ‘reserved’ values into a potentially longer sequence that contains no occurrences of those values. The extra length is referred to in this paper as the overhead of the algorithm. To date, byte stuffing algorithms, such as those used by SLIP [RFC1055], PPP [RFC1662] and AX.25 [ARRL84], have been designed to incur low average overhead but have made little effort to minimize worst case overhead. Some increasingly popular network devices, however, care more about the worst case. For example, the transmission time for ISM-band packet radio transmitters is strictly limited by FCC regulation. To adhere to this regulation, the practice is to set the maximum packet size artificially low so that no packet, even after worst case overhead, can exceed the transmission time limit. This paper presents a new byte stuffing algorithm, called Consistent Overhead Byte Stuffing (COBS), that tightly bounds the worst case overhead. It guarantees in the worst case to add no more than one byte in 254 to any packet. Furthermore, the algorithm is computationally cheap, and its average overhead is very competitive with that of existing algorithms.
Introduction to Embedded Systems - A Cyber-Physical Systems Approach
This book strives to identify and introduce the durable intellectual ideas of embedded systems as a technology and as a subject of study. The emphasis is on modeling, design, and analysis of cyber-physical systems, which integrate computing, networking, and physical processes. This book is intended for students at the advanced undergraduate level or the introductory graduate level, and for practicing engineers and computer scientists who wish to understand the engineering principles of embedded systems.
Design and Implementation of the lwIP Stack
LwIP is an implementation of the TCP/IP protocol stack. The focus of the lwIP stack is to reduce memory usage and code size, making lwIP suitable for use in small clients with very limited resources such as embedded systems. In order to reduce processing and memory demands, lwIP uses a tailor made API that does not require any data copying. This report describes the design and implementation of lwIP. The algorithms and data struc- tures used both in the protocol implementations and in the sub systems such as the memory and bu®er management systems are described. Also included in this report is a reference manual for the lwIP API and some code examples of using lwIP.
Time in Wireless Embedded System
Wireless embedded networks have matured beyond academic research as industry now considers the advantages of using wireless sensors. With this growth, reliability and real-time demands increase, thus timing becomes more and more relevant. In this dissertation, we focus on the development of highly stable, low-power clock systems for wireless embedded systems. Wireless embedded networks, due to their wire-free nature, present one of the most extreme power budget design challenges in the field of electronics. Improvements in timing can reduce the energy required to operate an embedded network. However, the more accurate a time source is, the more power it consumes. To comprehensively address the time and power problems in wireless embedded systems, this dissertation studies the exploitation of dual-crystal clock architectures to combat effects of temperature induced frequency error and high power consumption of high-frequency clocks. Combining these architectures with the inherent communication capabilities of wireless embedded systems, this dissertation proposes two new technologies; (1) a new time synchronization service that automatically calibrates a local clock to changes in temperature; (2) a high-low frequency timer that allows a duty-cycled embedded system to achieve ultra low-power sleep, while keeping fine granularity time resolution offered only by high power, high frequency clocks.
Topics in Secure Embedded System Design
Pervasive networks have led to widespread use of embedded systems, like cell phones, PDAs, RFIDs etc., in increasingly diverse applications. Many of these embedded system appli- cations handle sensitive data (e.g., credit card information on a mobile phone/PDA) or perform critical functions (e.g., medical devices or automotive electronics), and the use of security protocols is imperative to maintain con dentiality, integrity and authentication of these applications. Typically embedded systems have low computing power and nite energy supply based on a battery, and these factors are at odds with the computationally intensive nature of the cryptographic algorithms underlying many security protocols. In addition, secure embedded systems are vulnerable to attacks, like physical tampering, malware and side-channel attacks. Thus, design of secure embedded systems is guided by the following factors: small form factor, good performance, low energy consumption (and, thus,longer battery life), and robustness to attacks. This thesis presents our work on tackling three issues in the design of secure embedded systems: energy consumption, performance and robustness to side-channel attacks. First, we present our work on optimizing the energy consumption of the widely employed secure sockets layer (SSL) protocol running on an embedded system. We discuss results of energy analysis of various cryptographic algorithms, and the manner in which this information can be used to adapt the operation of SSL protocol to save energy. Next, we present results of our experiments on optimizing the performance of Internet protocol security (IPSec) protocol on an embedded processor. Depending on the mode of operation, the IPSec computation is dominated by cryptographic or non-cryptographic processing. We demonstrate how both these components of the IPSec protocol can be optimized by leveraging the extensible and con gurable features of an embedded processor. Next, we introduce a satisfability-based framework for enabling side-channel attacks on cryptographic software running on an embedded processor. This framework enables us to identify variables in the software implementations which result in the disclosure of the secret key used. Thus, security of software implementations can be improved by better protection of these identified variables. Finally, we conclude by introducing a novel memory integrity checking protocol that has much lower communication complexity than existing Merkle tree-based protocols while incurring a modest price in computation on the processor. This scheme is based on Toeplitz matrices, and can be very efficiently realized on embedded systems with hardware extensions for bit matrix operations.
Open Source in Embedded System Development
This paper introduces the huge range of free and open source software available to the embedded software developer. Hardware modeling, software tool chains, operating systems (RTOS and Linux), middleware and applications are all covered. Today open source is spreading to the hardware world. The paper addresses the advantages and risks associated with using free and open source software, including the issues of quality, support and licensing.
Embedded Systems – Theory and Design Methodology
This book addresses a wide spectrum of research topics on embedded systems, including basic researches, theoretical studies, and practical work.
Real-time Image Processing on Low Cost Embedded Computers
In 2012 a federal mandate was imposed that required the FAA to integrate unmanned aerial systems (UAS) into the national airspace (NAS) by 2015 for civilian and commercial use. A significant driver for the increasing popularity of these systems is the rise in open hardware and open software solutions which allow hobbyists to build small UAS at low cost and without specialist equipment. This paper describes our work building, evaluating and improving performance of a vision-based system running on an embedded computer onboard such a small UAS. This system utilises open source software and open hardware to automatically land a multi-rotor UAS with high accuracy. Using parallel computing techniques, our final implementation runs at the maximum possible rate of 30 frames per second. This demonstrates a valid approach for implementing other real-time vision based systems onboard UAS using low power, small and economical embedded computers.
An Embedded Object Approach to Embedded System Development
Building an embedded system from an idea to a product is a slow and expensive process requiring a lot of expertise. Depending on the developer’s expertise, the required quantity and price level of the final product, and the time and money available for development, the developer can build a device from different granularity of components, ranging from ready-made platforms, kits, and modules to individual components. Generally, solutions requiring less expertise, time and money produce products with higher production costs. The main contribution of this thesis is the EOC (Embedded Object Concept) and Atomi II Framework. EOC utilizes common object-oriented methods used in software by applying them to small electronic modules, which create complete functional entities. The conceptual idea of the embedded objects is implemented with the Atomi II framework, which contains several techniques for making the EOC a commercially feasible implementation. The EOC and the Atomi II Framework decreases the difficulty level of making embedded systems by enabling a use of ready-made modules to build systems. It enables automatic conversion of a device made from such modules into an integrated PCB, lowering production costs compared to other modular approaches. Furthermore, it also enables an automatic production tester generation due to its modularity. These properties lower the number of skills required for building an embedded system and quicken the path from an idea to a commercially applicable device. A developer can also build custom modules of his own if he possesses the required expertise. The test cases demonstrate the Atomi II Framework techniques in real world applications, and demonstrate the capabilities of Atomi objects. According to our test cases and estimations, an Atomi based device becomes approximately 10% more expensive than a device built from individual components, but saves up to 50% time, making it feasible to manufacture up to 10-50k quantities with this approach.
Driving I2C-Bus Signals Over Twisted Pair Cables with PCA9605
The availability of powerful I2C buffers that drive their I/Os on both sides to a nominal ground or ‘zero offset’ logic level allows the removal of noise introduced into one section of a larger bus system. That ‘regeneration’ of clean I2C signals enables building long I2C buses by combining together relatively short bus sections, each say less than 20 meters, using such buffers or multiplexers that contain them. Conventional twisted pair communication cabling with its convenient connectors, and a ‘modular’ I2C system approach, make large system assembly easy. Each drop point or node can be individually selected for bidirectional data communication with the Master just by using normal I2C software addressing. As an example, a system is described for control of LED lighting displays and it is suggested that the power for the LEDs, and the I2C control system, might be economically provided using ‘extra low voltage’ distribution at 48 V using either the control signal cable or similar low cost wiring in a manner similar to that used in ‘Power over the Ethernet’ systems. The simplicity and flexibility of this approach makes it attractive to consider as an alternative to other control systems such as RS-485 or CAN bus.
Five Steps to Improving Security in Embedded Systems
In today’s increasingly interconnected world, security breaches are becoming ever more prevalent, with escalating complexity challenges. How can embedded device developers balance the need for tighter security with competing business and market demands? This paper outlines five steps for building additional security assurance into embedded devices by considering the whole product lifecycle.
Creating a State-of-the Art, Cost Effective Energy Harvesting Bluetooth® Low Energy Switch
As IoT rapidly grows into new markets such as MHealth, Agriculture 4.0, and building automation, new questions are being raised about the energy required to support its growth. Within the industry, we see a broad spectrum of power requirements.
Open Source in Embedded System Development
This paper introduces the huge range of free and open source software available to the embedded software developer. Hardware modeling, software tool chains, operating systems (RTOS and Linux), middleware and applications are all covered. Today open source is spreading to the hardware world. The paper addresses the advantages and risks associated with using free and open source software, including the issues of quality, support and licensing.
Demystifying digital signal processing (DSP) programming: The ease in realizing implementations with TI DSPs
Introduced by Texas Instruments over thirty years ago, the digital signal processor (DSP) has evolved in its implementation from a standalone processor to a multicore processing element and has continued to extend in its range of applications. The breadth of software development tools for the DSP has also expanded to accommodate diverse sets of programmers. From small, low power, yet “smart” devices with applications such as voice and image recognition, to multicore, high-performance compute platforms performing real-time data analytics, the opportunities to achieve the low-power processing efficiencies of DSPs are nearly endless. The TI DSP has benefited from a relatively unique tool suite evolution making it easy and effective for the general programmer and the signal processing expert alike to quickly develop their application code. This paper addresses how TI DSP users are able to achieve the high performance afforded by the TI DSP architecture, in an efficient, easy-to-use development environment.
Arduino Microcontroller Guide
The Arduino microcontroller is an easy to use yet powerful single board computer that has gained considerable traction in the hobby and professional market. The Arduino is open-source, which means hardware is reasonably priced and development software is free. This guide is for students in ME 2011, or students anywhere who are confronting the Arduino for the first time. For advanced Arduino users, prowl the web; there are lots of resources.
Introduction to Arduino
The purpose of this book is to get you started on the road to creating things using micro-controllers. We will discuss only enough electronics for you to make the circuits, and only enough programming for you to get started. The focus will be on your making things. It is my hope that as you go through this book you will be flooded with ideas of things that you can make.
What’s a Multicore Microcontroller?
This tutorial answers the question “What’s a multicore microcontroller?”
New Life for Embedded Systems in the Internet of Things
The Internet of Things (IoT) is no longer a fanciful vision. It is very much with us, in everything from factory automation to on-demand entertainment. Yet by most accounts, the full potential of interconnected systems and intelligent devices for changing the way we work and live has barely been tapped. Up until now, IoT software solutions have largely had to be built from scratch with a high degree of customization to specific requirements, which has driven up the cost and complexity of development and deterred many prospective entrants to the market. What have been missing are developer tools that alleviate the costs associated with building the foundational infrastructure—the “plumbing” of their solutions—so they can focus on optimizing the core functionality and bring solutions to market more quickly with less cost. Wind River® is addressing these challenges with new solutions that have the potential to expand the market for IoT by reducing the cost and complexity of development. This document outlines the challenges that IoT poses for developers, and how Wind River solutions can help overcome them.
Freescale Trust Computing and Security in the Smart Grid
With the increasing deployment of automated technical solutions in the implementation of automated metering reading (AMR), advanced metering infrastructure (AMI) and smart grid infrastructure, possibilities of security attacks like data hacking, introducing malware in the system and cyber attacks are on the rise as well. Vulnerabilities in AMI devices include non-secure data buses, serial connections or remote access to debug port. The question arises: how can data security and customer privacy in smart meters and smart energy gateways be ensured? This paper talks about how trusted computing helps resolve security issues in implementing the smart grid by providing a clear idea of what elements of the system are trusted—and to what level and why. Freescale solutions that embed trusted computing are also covered.
Real-time Image Processing on Low Cost Embedded Computers
In 2012 a federal mandate was imposed that required the FAA to integrate unmanned aerial systems (UAS) into the national airspace (NAS) by 2015 for civilian and commercial use. A significant driver for the increasing popularity of these systems is the rise in open hardware and open software solutions which allow hobbyists to build small UAS at low cost and without specialist equipment. This paper describes our work building, evaluating and improving performance of a vision-based system running on an embedded computer onboard such a small UAS. This system utilises open source software and open hardware to automatically land a multi-rotor UAS with high accuracy. Using parallel computing techniques, our final implementation runs at the maximum possible rate of 30 frames per second. This demonstrates a valid approach for implementing other real-time vision based systems onboard UAS using low power, small and economical embedded computers.
Five Steps to Improving Security in Embedded Systems
In today’s increasingly interconnected world, security breaches are becoming ever more prevalent, with escalating complexity challenges. How can embedded device developers balance the need for tighter security with competing business and market demands? This paper outlines five steps for building additional security assurance into embedded devices by considering the whole product lifecycle.
Introduction to Embedded Systems - A Cyber-Physical Systems Approach
This book strives to identify and introduce the durable intellectual ideas of embedded systems as a technology and as a subject of study. The emphasis is on modeling, design, and analysis of cyber-physical systems, which integrate computing, networking, and physical processes. This book is intended for students at the advanced undergraduate level or the introductory graduate level, and for practicing engineers and computer scientists who wish to understand the engineering principles of embedded systems.
Real-time Image Processing on Low Cost Embedded Computers
In 2012 a federal mandate was imposed that required the FAA to integrate unmanned aerial systems (UAS) into the national airspace (NAS) by 2015 for civilian and commercial use. A significant driver for the increasing popularity of these systems is the rise in open hardware and open software solutions which allow hobbyists to build small UAS at low cost and without specialist equipment. This paper describes our work building, evaluating and improving performance of a vision-based system running on an embedded computer onboard such a small UAS. This system utilises open source software and open hardware to automatically land a multi-rotor UAS with high accuracy. Using parallel computing techniques, our final implementation runs at the maximum possible rate of 30 frames per second. This demonstrates a valid approach for implementing other real-time vision based systems onboard UAS using low power, small and economical embedded computers.
Open Source in Embedded System Development
This paper introduces the huge range of free and open source software available to the embedded software developer. Hardware modeling, software tool chains, operating systems (RTOS and Linux), middleware and applications are all covered. Today open source is spreading to the hardware world. The paper addresses the advantages and risks associated with using free and open source software, including the issues of quality, support and licensing.
Embedded Systems – Theory and Design Methodology
This book addresses a wide spectrum of research topics on embedded systems, including basic researches, theoretical studies, and practical work.
Consistent Overhead Byte Stuffing
Byte stuffing is a process that transforms a sequence of data bytes that may contain ‘illegal’ or ‘reserved’ values into a potentially longer sequence that contains no occurrences of those values. The extra length is referred to in this paper as the overhead of the algorithm. To date, byte stuffing algorithms, such as those used by SLIP [RFC1055], PPP [RFC1662] and AX.25 [ARRL84], have been designed to incur low average overhead but have made little effort to minimize worst case overhead. Some increasingly popular network devices, however, care more about the worst case. For example, the transmission time for ISM-band packet radio transmitters is strictly limited by FCC regulation. To adhere to this regulation, the practice is to set the maximum packet size artificially low so that no packet, even after worst case overhead, can exceed the transmission time limit. This paper presents a new byte stuffing algorithm, called Consistent Overhead Byte Stuffing (COBS), that tightly bounds the worst case overhead. It guarantees in the worst case to add no more than one byte in 254 to any packet. Furthermore, the algorithm is computationally cheap, and its average overhead is very competitive with that of existing algorithms.
Design and Implementation of the lwIP Stack
LwIP is an implementation of the TCP/IP protocol stack. The focus of the lwIP stack is to reduce memory usage and code size, making lwIP suitable for use in small clients with very limited resources such as embedded systems. In order to reduce processing and memory demands, lwIP uses a tailor made API that does not require any data copying. This report describes the design and implementation of lwIP. The algorithms and data struc- tures used both in the protocol implementations and in the sub systems such as the memory and bu®er management systems are described. Also included in this report is a reference manual for the lwIP API and some code examples of using lwIP.
Introduction to Arduino
The purpose of this book is to get you started on the road to creating things using micro-controllers. We will discuss only enough electronics for you to make the circuits, and only enough programming for you to get started. The focus will be on your making things. It is my hope that as you go through this book you will be flooded with ideas of things that you can make.
Time in Wireless Embedded System
Wireless embedded networks have matured beyond academic research as industry now considers the advantages of using wireless sensors. With this growth, reliability and real-time demands increase, thus timing becomes more and more relevant. In this dissertation, we focus on the development of highly stable, low-power clock systems for wireless embedded systems. Wireless embedded networks, due to their wire-free nature, present one of the most extreme power budget design challenges in the field of electronics. Improvements in timing can reduce the energy required to operate an embedded network. However, the more accurate a time source is, the more power it consumes. To comprehensively address the time and power problems in wireless embedded systems, this dissertation studies the exploitation of dual-crystal clock architectures to combat effects of temperature induced frequency error and high power consumption of high-frequency clocks. Combining these architectures with the inherent communication capabilities of wireless embedded systems, this dissertation proposes two new technologies; (1) a new time synchronization service that automatically calibrates a local clock to changes in temperature; (2) a high-low frequency timer that allows a duty-cycled embedded system to achieve ultra low-power sleep, while keeping fine granularity time resolution offered only by high power, high frequency clocks.
An Embedded Object Approach to Embedded System Development
Building an embedded system from an idea to a product is a slow and expensive process requiring a lot of expertise. Depending on the developer’s expertise, the required quantity and price level of the final product, and the time and money available for development, the developer can build a device from different granularity of components, ranging from ready-made platforms, kits, and modules to individual components. Generally, solutions requiring less expertise, time and money produce products with higher production costs. The main contribution of this thesis is the EOC (Embedded Object Concept) and Atomi II Framework. EOC utilizes common object-oriented methods used in software by applying them to small electronic modules, which create complete functional entities. The conceptual idea of the embedded objects is implemented with the Atomi II framework, which contains several techniques for making the EOC a commercially feasible implementation. The EOC and the Atomi II Framework decreases the difficulty level of making embedded systems by enabling a use of ready-made modules to build systems. It enables automatic conversion of a device made from such modules into an integrated PCB, lowering production costs compared to other modular approaches. Furthermore, it also enables an automatic production tester generation due to its modularity. These properties lower the number of skills required for building an embedded system and quicken the path from an idea to a commercially applicable device. A developer can also build custom modules of his own if he possesses the required expertise. The test cases demonstrate the Atomi II Framework techniques in real world applications, and demonstrate the capabilities of Atomi objects. According to our test cases and estimations, an Atomi based device becomes approximately 10% more expensive than a device built from individual components, but saves up to 50% time, making it feasible to manufacture up to 10-50k quantities with this approach.
