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October 29, 2012

Tech Focus

Managing interrupts for low latency response time

Improve Cortex M4 MCU interrupt responses with an Intelligent Peripheral Event System

Interrupts short and simple: Part 1 - Good programming practices

Introduction to Interrupt Debugging

Introduction to Interrupts


Editor's Note

Bernard Cole Bernard Cole
Site Editor
Embedded.com
bccole@acm.org
Read his blog

No matter whether it is design based on an 8-bit or 16-bit MCU, a 32-bit ARM or Atom, or a multicore SoC, one common challenge faces the embedded system developer: as a system's functional requirements and the size of the software grow, it becomes more difficult to ensure that time-critical operations are performed with as little interruption as possible.

The problems can be addressed by either using a faster processor - which is not realistic in many resource-constrained designs - or more commonly execute them in a prioritized manner, through the use of a variety of interrupt management and scheduling schemes.

But this is not achieved easily, as the designer is faced with a variety of roadblocks. Because software cannot predict when interrupts will occur and thus pause execution of other operations, it is no surprise that without a considerable degree of effort, the result is the inability to perform system and application critical operations within the design constraints originally defined.

Collected here are a range of design articles, white papers, webinars and columns by Jack Ganssle, Jack Crenshaw and Dan Saks to help you sort through the problems and their possible solutions. In addition to "Improve Cortex M4 MCU interrupt responses with an Intelligent Peripheral Event System," by Andreas Eieland, and Espen Krangnes, and "Interrupts short and simple," a three part series of tutorials by Priyadeep Kaur, my Editor's Top Picks are:

Optimized interrupt handling
Testing the Interrupt Priority Levels of a Microprocessor
Introduction to interrupt debugging

Editor's Note: Planning is currently underway for the program of events and classes at the Spring ESC DESIGN West in April, 2013. If there is a topic you think is important to communicate to your fellow embedded systems developers, submit an abstract, right away. Submission deadline is Nov. 2, the end of this week. We are also looking for ideas for the keynote events, so go to "Design your own keynote," and leave your suggestions about topics and speakers.


Development

Improve Cortex M4 MCU interrupt responses with an Intelligent Peripheral Event System

In this Product How-To design article, Atmel's Andreas Eilan and Espen Krangnes describe how they improved interrupt response times and reduced device driver development time for developers of applications using the company's Cortex M4 MCU based implementation with the use of an intelligent Peripheral Even System previously used on its 8- and 16-bit MCUs

Interrupts short and simple: Part 1 - Good programming practices

In this first part in a series on the appropriate use of interrupts in embedded systems design, Priyadeep Kaur of Cypress Semiconductor starts with general guidelines and good practices that should be followed.

Interrupts short & simple: Part 2 - Variables, buffers & latencies

In this second part in an on-going series on the appropriate use of interrupts in a variety of embedded systems design environments, Priyadeep Kaur discusses ISRs, global/local variables, data buffers, shared memory and the interrupt timing latencies.

Interrupts short and simple: Part 3 - More interrupt handling tips

In this third part in a series on the appropriate use of interrupts in embedded systems design, Priyadeep Kaur discusses right and wrong practices while using buffers with ISRs.

Reduce RTOS latency in interrupt-intensive apps

Here is a way to bypass the RTOS in latency-sensitive interrupt situations. The use of a hybrid interrupt handling technique may reduce or eliminate the latency introduced by the RTOS in many embedded designs

Minimize your ISR overhead

With all the automated tools available today, it's easy to lose track of the overhead that such tools are introducing.

Interrupts in C++

An ideal C++ device driver would be a class containing, among other things, the ISR as a member function. But this is harder to achieve than many C programmers assume.

Interrupt Management Under Linux: Using the Interrupt Controller API

Bill Gatliff provides a walkthrough of the portions of the Linux kernel that manage interrupts and describes how Linux interacts with interrupt controllers and how to adapt code for custom hardware.

Building Bare-Metal ARM Systems with GNU: Part 1 - Getting Started

In this first part in an on-going series of ten articles, Miro Samek of Quantum Leaps details developing apps on the ARM processor using QNU, complete with source code in C and C++. First up, laying the ground work

Back to the basics: Doing Hardware Counter/Timer design using High School Science

Using the same unit-conversion techniques and dimensional analysis techniques learned in high school, Zane Purvis takes non-engineers and newcomers to embedded design step-by-step through the configuration of a counter/timer.


Products

Tektronix introduces one-stop PCIe 3.0 testing and debug

Tektronix now offers designers a single destination for PCI Express 3.0 testing with its automated transmitter (Tx) and receiver (Rx) compliance and debug testing solution for the PCI Express 3.0 standard.

Atmel combines maXTouch controllers and maXFusion technology on a single chip

Atmel Corporation has announced new microcontroller-based solutions that integrate touch and sensor hub functionality for a variety of mobile devices including smartphones, tablets, Ultrabooks and convertible PCs.

Telit LTE cellular module delivers 100Mbps download with fallback to HSPA+/GSM/GPRS

The LE920 LTE cellular module from Telit Wireless Solutions features a new 920 form factor measuring 34x40x2.8mm on a 198-pad LGA automotive-grade package.


Industry

FRAM helps TI cut power for Wolverine MSP430 platform

Wolverine is the moniker chosen by Texas Instruments for an ultra-low-power MSP430 microcontroller platform launched here which provides 360 nA real-time clock mode - more than doubling battery life - and less than 100 μA/MHz active power consumption.

LDRA tool suite supports integration with VisualDSP++

LDRA has integrated its tools suite with the Analog Devices VisualDSP++ (VDSP++) software development environment. The tool suite provides automated software testing and verification across all stages of software development.

Cortex-M based MCUS use power profiles to optimize performance

With its latest Cortex-based LPC1100L and LPC1300L microcontrollers NXP Semiconductors is aiming to raise the benchmarks in 32-bit active power consumption.

Get Connected with the Connecting Edge – A new online community from TE
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Insights

Interrupt latency

Knowledge is power, but often we don't know what's really happening in our systems. This column contains some tricks to help you find out.

Disabling interrupts

Accessing shared resources is harder than one thinks

Introduction to interrupts

Normal execution of a given software application is contained within the bounds of one program, or instruction stream. Such execution is provable, as well as traceable. However, system designers and implementers also have to understand how breaks in

Modeling interrupt vectors

Just as you can often treat device registers as a memory-mapped struct, you can treat an interrupt vector as a memory-mapped array.

Introduction to interrupt debugging

Interrupt-related problems are among the hardest to debug. Here's a primer on some common pitfalls to avoid.


Collections on Embedded.com

Embedded.com now has a series of collections of content by topic. We will continue to add content to our collections and will have a rating system in the near future where you can rate your favorite articles (and help others find them). To suggest new collections or to suggest content to add to a collection, contact Susan Rambo, managing editor.

New collection:

Best practices in embedded systems programming

Browse the collections:

A sampling of topics include:
Algorithms
PID control
Digital signal processing
Multicore
Agile programming
Watch Dog Timers


TechOnline Library

Tech Papers

Optimized Interrupt Handling

Interrupt Management Under Linux

Zero Overhead Interrupt Segmentation

Techniques to Disable Global Interrupts

Testing the Interrupt Priority Levels of a Microprocessor

Reducing Interrupt Latency Through the Use of Message Signaled Interrupts

Webinars & Courses

Improve Linux Real-time Behavior with a new Light-weight Threading Model

High Performance, Low Latency Interconnect for AMBA 4 AXI4

Hazards of Multi-threaded and Multi-core Software Development

Designing with the Atmel® XMEGA


Resources

Around the Network Events

Integrated Task and Interrupt Management for Real-Time Systems

Source-aware Interrupt Scheduling for Parallel I/O Systems

Device Handler Migration and Direct Interrupt Scheduling



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Conferences and Events

ESC Silicon Valley Call for Abstracts
Deadline is November 2, 2012:
The Embedded Systems Conference (now part of DESIGN West) is soliciting proposals from speakers with deep technical expertise for the technical conference program and speed-training theater sessions at the ESC Silicon Valley 2013 (April 22 through 25 in San Jose, California). "This year for the first time we're actively soliciting real-world case studies, talks that include demos, and all elements of the design cycle--from concept through to production." says Karen Field, interim conference director.

ESC tracks include:
--Connectivity and networking
--Debugging and test
--Embedded Android
--"Hello World": focused on the latest hardware and software development tools
--Hardware: Design, I/O, and Interfacing
--Linux Kernel and operating systems
--Low-Power design
--Processors and programmable devices
--Programming
--Prototyping
--Real time operating systems
--Safety, security & hacking embedded systems
--Systems design

For more info on tracks and submitting, click here. Submit proposals by November 2, 2012.

Mark your calendar

Registration is now open for Embedded Systems Conference 2013 (part of DESIGN West), to be held April 22 to 25, 2013 at the McEnery Convention Center, San Jose, CA. Super-early pricing available now (save $800 on All-Access Pass).

ARM TechCon 2012 is October 30 through November 1, 2012 at the Santa Clara Convention Center, Santa Clara, CA.
Oct. 30 is Chip Design Day
Oct. 31 through Nov. 1 are the Software & Systems Design Days
Tracks include:
--Android / open source
--Compute platforms
--Developing & debugging
--Low-power design
--Microcontroller and programmable platforms
--Multimedia processing
--Networking & connectivity
--Safety & security
--Software optimization on ARM-powered systems
--The fundamentals of ARM

For more industry events, visit Embedded.com's event page.



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