Driving I2C-Bus Signals Over Twisted Pair Cables with PCA9605

NXP Semiconductors

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.


C++ Tutorial

Juan Soulié
5 comments

These tutorials explain the C++ language from its basics up to the newest features of ANSI-C++, including basic concepts such as arrays or classes and advanced concepts such as polymorphism or templates. The tutorial is oriented in a practical way, with working example programs in all sections to start practicing each lesson right away


Arduino Programming Notebook

Brian W. Evans

This notebook serves as a convenient, easy to use programming reference for the command structure and basic syntax of the Arduino microcontroller. To keep it simple, certain exclusions were made that make this a beginner’s reference best used as a secondary source alongside other websites, books, workshops, or classes. This decision has lead to a slight emphasis on using the Arduino for standalone purposes and, for example, excludes the more complex uses of arrays or advanced forms of serial communication.


Introduction to Embedded Systems - A Cyber-Physical Systems Approach

E. A. Lee, S. A. Seshia
3 comments

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.


Embedded Systems – Theory and Design Methodology

Kiyofumi Tanaka (Editor)
3 comments

This book addresses a wide spectrum of research topics on embedded systems, including basic researches, theoretical studies, and practical work.


High Performance Systems, Applications and Projects

Kiyofumi Tanaka (Editor)
1 comment

This book addresses a wide spectrum of research topics of embedded systems, including parallel computing, communication architecture, application-specific systems, and embedded systems projects.


Lessons in Electric Circuits - Volume III - Semiconductor

Tony R. Kuphaldt
2 comments

This book covers all of the common semiconductor devices and their principles of operation. However, the true value of this reference is in the fact that it provides key circuits and applications where they come in handy. A few of the devices that are covered in this book are Bipolar junction transistors, diodes, JFETs, thyristors, OPAMPs and FETs. This book will be a good reference in your library that has a clear style of explanation.


Embedded Linux Primer

Christopher Hallinan
4 comments

This book brings together indispensable knowledge for building efficient, high-value, Linux-based embedded products: information that has never been assembled in one place before. Drawing on years of experience as an embedded Linux consultant and field application engineer, Christopher Hallinan offers solutions for the specific technical issues you're most likely to face, demonstrates how to build an effective embedded Linux environment, and shows how to use it as productively as possible.


A Guide to Approximations

Jack G. Ganssle

Most embedded processors don’t know how to compute trig and other complex functions. Programming in C we’re content to call a library routine that does all of the work for us. Unhappily this optimistic approach often fails in real time systems where size, speed and accuracy are all important issues. The compiler’s runtime package is a one-size-fits-all proposition. It gives a reasonable trade-off of speed and precision. But every embedded system is different, with different requirements. In some cases it makes sense to write our own approximation routines. Why?


Consistent Overhead Byte Stuffing

Stuart Cheshire, Mary Baker

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.