Nuts & Volts - September 2005

In The Trenches

guage will have a significant impact on the development of the software. You certainly don’t want to design web pages with COBOL or a database manager in Postscript. Generally, the language choice will be fairly obvious. There are a number of specialized languages for specialized applications. For generic software, a general-purpose language is appropriate.

To limit the scope of discussion, let’s look at one-person software development that supports a hardware product. For example, this could be a uC that controls a microwave oven or a PC-based data-acquisition system.

For PC-based software, you will clearly want to use a high-level language. There are several specialized languages available, and you should learn which of those are appropriate for your application. Most general programming is done with a variation of the C language; C+ and C++ are the most common. These are good general-purpose languages that are suitable for many applications.

For uC applications, assembly language and C+ are typical. However, an important stipulation is that you should always be proficient in the assembly language for that uC because there are times when a high-level language creates too much overhead for efficient code. For real-time applications, it is not unusual to require the maximum speed of the uC. This can only be accomplished in assembly. Additionally, if you don’t know assembly, you are at the mercy of limitations of the high-level language.

(sometimes called “assembled”) is converted into machine language by an external program called a compiler (or assembler). This machine language translation is then loaded into the computer and executed. The compiler is only used during translation, not during execution.

An interpreter permanently resides in the computer and converts one line

of code into machine language and executes that code immediately. Then it takes the next line of code and converts that, and so forth. This line-by-line conversion/execution method is slow, but it has the advantage of being easy. You don’t have to load a compiler, link various files, set compilation attributes, and so on. You just hit “RUN.” For beginners, this powerful simplicity is

Atmel AVRbased Micro64/128

Embedded Controller Module

8-Channel Analog to Digital Convertor

Real Time Clock/Calender 29 Digital I/O SPI & I²C Bus

Two Serial Ports

Serial Boot Loader

RS-232, 422 or 485

Selectable Baud

Rates up to 250 Kbps

Only 1.5 Cubic Inches

Supports Assembly,

BASIC and C Prog. Languages

Inexpensive CodeVision C Compiler

Starting at Only $119 - Single Qty

Basic as a Language Choice

Basic (Beginners All-purpose Symbolic Instruction Code) is easy to learn and has lots of useful instructions. However, it is not a good choice for commercial software development. Before I get a lot of angry letters, let’s examine why this is the case.

First, Basic is an “interpreter,” while most other languages are compiled. This difference is very important. A program that is compiled

SEPTEMBER 2005

Start Developing

The Micro6/128 Development Board takes the Micro64/128 I/O pins and expands them out to solder pads and headers for ease of connection when developing. It also connects USART1 to RS-232 drivers or directly to screw terminals for RS-422 or RS-485 communication. USART0 is also connected to RS-232 drivers. The RS-232 drivers are connected to two DB9 connectors. This board

includes a prototyping area so the user can add external circuitry. There is an onboard voltage regulator for powering the Micro64/128 and additional circuitry. The Micro64/64A/128/128A development system comes complete with a Micro64, Micro64A, Micro128 or Micro128A, a Micro64/128 Development Board, and a power supply.