Micro-contrôleurs et robotique

Le premier micro-contrôleur au monde: Intel 8048

Le micro-contrôleur est fondamentalement un ordinateur qui est placé sur une simple puce de circuit intégré. Il est composé d'une mémoire, d'un processeur aussi bien que des interfaces d'entrée/sortie. Le microcontrôleur est programmé pour exécuter certaines tâches, ce qui signifie que s'il y a un besoin de changer ou améliorer cette fonctionnalité, il suffit d'installer un nouveau programme sur la puce. Les aspects qui différencient les micro-contrôleurs d'autres ordinateurs (le PC, l'ordinateur portable, le serveur, etc) sont :

• Toutes les fonctions sont placés sur une simple puce sur une échelle plus compacte et plus petite.
• Il est programmé pour exécuter certaines tâches, afin de changer ses fonctionnalités on doit installer un nouveau programme.
• Il ne consomme que très peu d'énergie, parce que ses caractéristiques physiques sont plus petites et moins gourmande en énergie qu'un PC classique, un ordinateur portable ou un serveur. Habituellement les dévelopeurs de micro-contrôleurs se concentrent sur la basse consommation d'énergie, ce qui permet d'utiliser plus longtemps les batteries des applications mobiles.
• Single purpose inputs and outputs. Les micro-contrôleurs ont des périphériques, qui établissent la connexion entre le micro-contrôleur et d'autres micro-contrôleurs ou des ordinateurs (par exemple USB, PEUT, UART), aidant à comprendre les processus dans le monde physique réel (par exemple les interrupteurs, la mesure de température, etc) et aidant à contrôler l'environnement (par exemple pour contrôler le moteur, déclencher une alerte etc).

Microcontrollers can be found in a variety of everyday items: household appliances (e.g. microwave oven, TV-set), toys (Lego NXT, talking dolls), vehicles (cars, hoists), etc. Microcontrollers’ very wide usage has been possible because they are easy to program and have wide range of functionality, hence is very easy to add new features and upgrade the level intelligence of the appliance they are in.

Robotics is science which combines technology and knowledge necessary to build robots. Due to fast development of technology the term robot, as an automatic machine that replaces human, is not so clear anymore. Robot is not anymore just humanoid robot, robotic hand at automotive industry’s assembly line, autopilot in aircraft, artificial intelligence built of living neurons or simple cleaning robot, it is also computer software witch completes tasks that human has to do (for example complies reports). It is known that robots are built to replace humans at certain tasks. There are many reasons for this: dangerous working conditions, cheaper production, monotonous work may cause humans to err, new systems are so complex and time critical, that automatic system makes better decisions than human.

Because of the wideness of the robotics, we determinate it as hobby robotics, the systems are not very complex there and it is possible to build them alone. Common microcontrollers in hobby robotics are:

• Atmel AVR microcontrollers (ATmega, ATtiny, etc.)
• Microchip Technology PIC microcontrollers (PIC16, PIC24, etc.)
• Microcontrollers based on ARM technology.

Quite often third parties have created development boards and environments based on microcontrollers mentioned herein before. For example: Arduino (AVR), BASIC Stamp (PIC) and Lego NXT (ARM). Necessaries for developing HomeLab witch are described hereinafter in this book are based on AVR ATmega128 microcontroller. Question arises from the large amount of microcontrollers and development boards available: how to find the most appropriate? Generally we can classify following four properties: - price, physical characteristics, development environment and customer support. Notable physical characteristics are:

• processor operating frequency - determines chip operating speed
• program memory capacity – determines the size of the program that can be installed on the chip
• data memory capacity – how much data can be processed in the program
• number of input/output pins and their function – different pins have different possibilities
• number of timers – important for pursue time criteria
• energy consumption – important for mobile applications

Here development environment is PC software, witch allows creating and compiling programs, uploading programs to the microcontrollers and bridging in the programs during work in order to detect possible faults. How easy and comfortable it is to do all that becomes decisive, because during development period of the program it will be the primary working area. All this leads to the fourth characteristic, witch is customer support. It is important that receiving help and support for solving possible issues is as easy as possible. By considering all four mentioned properties, it should be possible to find the development board needed.