Serial Carrier Card with Flexible I/O and Serial Technology

New 3U CompactPCI Serial Carrier Card from MEN Micro IntegratesThe G204 is a 3U CompactPCI Serial carrier card with an M-Module slot that combines fast CompactPCI Serial technology with flexible I/O options. The card serves as the basis for powerful 19″-based system solutions for transportation and industrial applications (e.g., data acquisition, process control, automation and vehicle control, robotics or instrumentation).

M-Modules are modular I/O extensions for industrial computers (e.g., embedded systems and high-end workstations). The M-Module slot enables users to interchange more than 30 I/O functions within a system. The M-Module, which needs only one CompactPCI Serial slot, is screwed tightly onto the G204 and does not require a separately mounted transition panel.

The G204 modular mezzanine card operates in a –40°C to 85°C extended temperature range for harsh environments and costs $483.

MEN Micro Inc.

Open-Source Guide for Embedded Systems Developers (EE Tip #114)

What comes to mind when you hear the term “open source”? Hopefully, it means more to you than just a software application running on a PC.

As an embedded systems developer, you should familiarize yourself with the wide range of open-source programs, programming tools, and hardware platforms currently available. In addition to saving yourself the costs of pricey user licenses, you’ll find that open-source community forums helpful, informative, and engaging.

Open-source software offers a number of advantages. The product is independent of a particular manufacturer and there aren’t license costs. Plus, the product is usually high quality because it is often supported by a large active community of users. When a program’s source code is available, you have the chance to fix errors, change its behavior, and even add new features.

The aforementioned advantages should be good enough reasons for any designer of microcontroller applications to work with open-source software. PC tools such as editors, documentation programs, toolchains (for the vast majority of microcontrollers), operating systems, and libraries are widely available with open-source code.

On the hardware side, open-source microcontroller boards are gaining popularity among serious engineers. The circuits, PCBs, and CAD files are available so you can modify them, improve them, and add more features to meet the demands of your applications. It’s an added benefit that open-source hardware is always supported by software code and libraries that enable you to get up and running fairly quickly.

Since we couldn’t include in the space provided all the open-source resources currently available, we simply list several open-source projects that Elektor and Circuit Cellar engineers and editors recommend.

Below we provide the following lists: hardware; libraries and run-time tools; PC tools, and GNU toolchains. By no means are the lists complete. Still, they’re helpful starting points.

Download your Arduino Uno poster

Click image to download a free Arduino Uno poster

Arduino—This popular platform offers a range of simple microcontroller and development boards that you can purchase from several suppliers. The Arduino website has an active forum and the wide range of software examples will ensure that you are up and running in minimum time.

Openmoko—It’s a complete software stack for a smart. The Neo FreeRunner mobile phone is the target hardware platform. Development and debug boards are also available.

GNU Radio & Universal Software Radio Peripheral—The GNU Radio project is a software toolkit to produce a software-defined radio. The open-source hardware for this project is the Universal Software Radio Peripheral (USRPBoard), which is based on an FPGA.

KiCAD—One of the best-known suites of CAD programs for hardware production, KiCAD includes tools for generating circuit diagrams and PCBs. You can view 3-D representations of the finished board.

Fab Lab—This interesting project offers 3-D laser cutters, 3-D printers, and other machines for use by the general public. It’s a handy resource for making robot parts and art objects.

uIP/lwIP—Two outstanding network stacks, the first is for 8-bit microcontrollers. lwIP is a development of the first and more suited to medium sized controllers. The uIP licence is not so strict allowing the stack to be used in commercial products.

LUFA (formally MyUSB)—A large library of applications for interfacing (both Host and Device) USB enabled AVR controllers. The demonstration applications allow an AVR controller for example to emulate a keyboard and many other devices (mass storage device, audio I/O etc.)OpenSource2

Crypto-avr-lib—It’s a library of optimized cryptographic routines for the Atmel ATmega controller. Issued under the GPL Version 3 licence. Contact the author for other types of licence.

FreeRTOS—FreeRTOS is a lightweight Real Time kernel which can run on many controller families. It can be used in commercial applications and allows the use of closed-source software.

U-Boot—Universal bootloader with a large range of routines for memory, UART interface, SD card, network and USB etc. Conceived originally as a bootloader but now through comprehensive hardware support can be used as the basis of a C code module.

Embedded Filesystems Library—A useful (FAT) file format, when you are short of memory. The GPL licence includes a clause allowing static linking to the library without public disclosure of your code.

.NET Micro Framework—Now open source this very compact, trimmed down .NET Framework running on diverse ARM platforms. Programmable using the object orientated C variant C#; lots of resources including support for I2C, Ethernet and many more. Helps reduce development time.

Eclipse—This is a good development environment. It has a modular structure which makes it very easy to configure. There are around 1,000 plug-in modules (both open source and commercial) for a range of program languages and target systems.

Kdevelop—Kdevelop is an integrated development environment which should satisfy most power-user needs. Runs in MS Windows, Mac OsX, Linux, Solaris and FreeBSD. Plug-in expandable.

Programmer’s Notepad—A lightweight but efficient editor for writing source code. Allows fast, simple and comfortable program production. Can be expanded with plug-ins.

Doxygen—An intelligent tool which can automatically generate code documentation (C, C++, Java etc.). The programmer provides tags in the source file; Doxygen generates the comprehensive documentation in PDF or HTML format. It can also extract the code structure from undocumented source files.

WinMerge—A good tool for code comparison and code synchronization. The program can also compare the contents of folders/files and display the results in a visual text format that makes it easy to understand.

Tera Term—A terminal program to access COM ports, supports Telnet communication Protocol. A debugging tool to eavesdrop on serial communications.

Note: Toolchains for GNU projects are available most processor architectures AVR, Coldfire, ARM, MIPS, PowerPC and Intel x86. The GNU-toolchain includes not only compilers for C, C++ and in most cases also Java (GCC = GNU Compiler Collection), but also Linkers, Assemblers and Debuggers together with C libraries (libc = C library). The tools are used from within other-open source projects, like WinAVR, which provides a familiar user interface to speed up program development.

One Desk Serves Two Roles for Professor and Designer

Chris Coulston, head of the Computer Science and Software Engineering department at Penn State Erie, The Behrend College, has a broad range of technical interests, including embedded systems, computer graphics algorithms, and sensor design.

Since 2005, he has submitted five articles for publication in Circuit Cellar, on projects and topics ranging from DIY motion-controlled gaming to a design for a “smart” jewelry pendant utilizing RGB LEDs.

We asked him to share photos and a description of the workspace in his Erie, PA, home. His office desk (see Photo 1) has something of an alter ego. When need and invention arise, he reconfigures it into an “embedded workstation.”

Coulston's workspace configured as an office desk

Photo 1: Coulston’s workspace configured as an office desk

When working on my projects, my embedded workstation contains only the essential equipment that I need to complete my project (see Photo 2).  What it lacks in quantity I’ve tried to make up for in quality instrumentation; a Tektronix TDS 3012B oscilloscope, a Fluke 87-V digital multimeter, and a Weller WS40 soldering iron.  While my workstation lacks a function generator and power supply, most of my projects are digital and have modest power requirements.

Coulston can reconfigure his desk into the embedded workstation pictured here.

Photo 2: Coulston can reconfigure his desk into the embedded workstation pictured here.

Coulston says his workspace must function as a “typical office desk” 80 percent of the time and electronics station 20 percent of the time.

It must do this while maintaining some semblance of being presentable—my wife shares a desk in the same space. The foundation of my workstation is a recycled desk with a heavy plywood backing on which I attached shelving. Being a bit clumsy, I’ve tried to screw down anything that could be knocked over—speakers, lights, bulletin board, power strip, cable modem, and routers.

The head of a university department has different needs in a workspace than does an electronics designer. So how does Coulston make his single office desk suffice for both his professional and personal interests? It’s definitely not a messy solution.

My role as department chair and professor means that I spend a lot time grading, writing, and planning. For this work, there is no substitute for uncluttered square footage—getting all the equipment off the working surface. However, when it’s time to play with the circuits, I need to easily reconfigure this space.

I have found organization to be key to successfully realize this goal. Common parts are organized in a parts case, parts for each project are put in their own bag, the active project is stored in the top draw, frequently used tools, jumper wires, and DMM are stored in the next draw. All other equipment is stored in a nearby closet.

I’ve looked at some of the professional-looking workspaces in Circuit Cellar and must admit that I am a bit jealous. However, when it comes to operating under the constraints of a busy professional life, I have found that my reconfigurable space is a practical compromise.

To learn more about Coulston and his technical interests, check out our Member Profile posted earlier this year.


Chris Coulston

Chris Coulston

CC 277: Using Files in Concurrent Linux Designs

In the August issue of Circuit Cellar, columnist Robert Japenga, who has been designing embedded systems since 1973, wraps up his eight-part series on the benefits and challenges of designing concurrency into your systems and some of the specific tools Linux provides for IPC.

His final installment discusses file usage. It also recounts how the development of read/write nonvolatile memory (i.e., flash technology) enabled embedded systems to contain cost-competitive file systems.

“Disk drives in the early days were too big and weren’t reliable enough for embedded systems. The first real disk drive I used in 1975 was a Digital Equipment RK-05 for a PDP-11 that held an amazing 2.5 MB of data,” Japenga says in his column. “The RK-05 was released in 1972. It initially weighed 100 lbs. The $74 monthly maintenance cost would buy a 1-TB drive today or 12 per year.

In 1972, a Digital Equipment RK-05 disk drive held only 2.5 MB of data. (Photo courtesy of Mark Csele)

“In 1977, a friend from Bell Labs carried an RK-05 with a copy of Unix onto a plane. At the gate, the inspector opened the lid and put his finger on the magnetic platter. Whoops. The disk gloriously crashed when inserted into my disk drive. It seemed I would have to wait for my first copy of Unix.

“”For a time, companies produced hardened disk drives. The cost was very prohibitive and the reliability was questionable. Then in 2001, the iPod changed all that when Apple used Toshiba’s 1.8” hard drive, which is only 0.2” thick. As a consumer product, it had to be extremely rugged. Very small embedded systems now had hard drives.

“But not all of us built millions of systems, nor could we afford to put a hard disk in our temperature controllers, motion-control devices, or avionics boxes. However, with the advent of read/write nonvolatile memory (i.e., flash technology), embedded systems now had a way to contain cost-competitive file systems. This paved the way for putting real OSes into embedded systems. In the late 1990s and later, we were putting DOS on a flash card. Well, not everything was a real OS! And that is where Linux comes into the picture.”

Japenga’s column goes on to discuss file systems and the mechanisms to create concurrent systems, including nonvolatile flag files, volatile flag files, data sharing, and event triggering. It concludes with a thorough discussion of some of the risks of using a file system in a concurrent system.

“Modern embedded systems are doing more than I ever imagined when I started out,” Japenga says. “Adding a file system to your design can provide significant advantages to improve your product. As with all OS functions, we need to understand how our file system works if we are going to use it properly—especially in systems with concurrency.”

For more, check out  Japenga’s column, Embedded in Thin Slices, in Circuit Cellar‘s August issue.