Servo - January 2008

C PROGRAMMING

for Microcontrollers Made Easy

New, no-cost online system cuts start-up time from hours to minutes

by Sam Christy

Many aspiring roboticists take their transition to writing C code for microcon- A Different Approach first steps in programming embed- trollers can be daunting. Not only do you ded controllers with interpreted have to learn a new programming lan- Machine Science, Inc., of languages, such as LOGO and Basic. guage, you also have to install a range Cambridge, MA, has developed a new These languages are fine entry points for of new software tools: a text editor or on-line system that radically simplifies beginners, but after a short time, their integrated development environment the process of developing C code for limitations can become frustrating. To (IDE) for writing and editing your code, a microcontrollers. This unique, patented tackle more sophisticated projects, C compiler that works with your chip, system enables users to write and com-sooner or later you will have to move up and a utility for downloading the pile code using an on-line interface, to writing code for microcontrollers in C. compiled code to your embedded device. rather than a locally installed IDE. The

With C, your code will run faster Finding all of the necessary software compiler is installed on a server, and and you will gain access to advanced tools and getting them to work together downloading is accomplished with a chip features, like interrupts and univer- properly is a major challenge, even for Java applet, so there is no software for sal asynchronous receiver/transmitter experienced developers. Most compilers the user to install or configure locally. (UART) capabilities. C is also designed provide little or no user interface. They To access the system, users simply to be portable, unlike Basic, whose work mysteriously in the background, log in to the Machine Science website myriad varieties can be incompatible waiting for instructions and files from and write their code in a text window, with one another. Moreover, since most the IDE. Within the IDE, command line which provides useful features such as professional developers program options must be set, telling the compiler editing tools, line numbering, and embedded controllers in C, there is a which chip is being used and what type color-coded C syntax highlighting wealth of C code available on-line to help of output file is expected. Likewise, the (Figure 1). Users can then compile their _get _you _started _on _your _next _{project. downloading} _software _has _to _be _{config- code} _and _send _the _compiled _hex _file _{to ured} _with _the _correct _oscillator _{settings, a} _{microcontroller} _in _real _time, _with _a_{Bootstrapping} _the0_Old _Way0_or _els1_e _the _code1_will _not _run2_correctly.0_single1_mouse _clic0_k. _Since _all1_of _the _soft1_-

Even after the IDE, compiler, and ware is server-based, the system works

For the novice, making the downloader have been installed and on both PCs and Macintosh computers. configured, there is the issue of library In addition to cutting set-up time, and header files. At this stage, the there are other advantages to using an novice programmer may have only raw on-line development environment for C — about 30 recognized words — to microcontroller projects. Code files are work with. Some C compilers come automatically stored on the server and with built-in code libraries, but others can be accessed from any Internet con-do not. So if you are trying to get start- nected computer. This is particularly ed inexpensively, there may be a fair handy if you want to work on the same amount of legwork left to do in order project at the office and at home, or at to establish basic coding functionality, different terminals in a high school or like delay routines and text output. university computer lab. As a resource All of this just to get to “Hello for users, Machine Science also pro-World,” or more likely, in the case of an vides a suite of code libraries, covering embedded controller, a blinking LED! everything from pulse width modulation (PWM) to controls for liquid crystal displays and other external devices.