Sensors, signals and movement
This broad section deals with the various pieces of hardware and software that allow computers and equipment to communicate, feel, see, hear, smell, sense and move.
Basic electronics
This section will cover topics on electronics.
Circuit design
There are several pieces of software available that help you design circuit schematics and circuit board layouts:
- Eagle Layout Software (http://www.cadsoftusa.com/)
- Fritzing (http://www.fritzing.org/)
Eagle
Eagle is not totally free. It has a freeware and professional version. The limit on the freeware is the size of board you can build, which probably is not an issue for small projects. Beyond this Eagle is a fully functioning professional circuit design software. It works like many CAD programs. There are Windows, Linux and Mac OS X, versions of the software. The interface can be a bit daunting at first, but if you understand circuit design, it isn’t too hard to go from schematic to board layout.
Fritzing
Fritzing is a very new project, as of this writing (still in alpha as of 1/30/2008) but looks promising. Its back end is actually built off of Eagle and so there for to use it full you need Eagle installed. But it is a bit more user friendly than Eagle allowing users to see designs made of more like real wires and boards than circuit diagrams.
Ohm's Law: Current, Voltage and Resistance
Ohm’s law is one of the most important ideas to understand in electronics. It describes the relationship between voltage, current and resistance. Ohm’s law was first presented in a 1827 treatise by German physicist Georg Ohm.
Voltage
Voltage is the measure of electrical pressure or potential. The greater the pressure the more current can pass
through the same conductor. The unit of Voltage is the Volt and is named for the Italian physicist Alessandro Volta.
Current
Current is the measurement of electrons through an electrical conductor. The unit for measuring current is the Amp or Ampere, named for the French physicist André-Marie Ampère.
Resistance
Resistance is the measure of how much a material resists or slows down an electrical current flowing through it. Every material including conductors have some resistance. The unit of resistance is the Ohm.
Resistor Codes
Resistors values are coded with colored stripes. The stripes are weighted to one end of the resistor. That is the end to start from. The first to stripes are digits, the third is a multipler and the fourth the tolerance of the resistor.
| Code | Digit | Multiplier |
|
| BLACK | 0 | 1 | |
| BROWN | 1 | 10 | |
| RED | 2 | 100 | |
| ORANGE | 3 | 1,000 | (1K) |
| YELLOW | 4 | 10,000 | (10K) |
| GREEN | 5 | 100,000 | (100K) |
| BLUE | 6 | 1,000,000 | (1M) |
| VIOLET | 7 | 10,000,000 | (10M) |
| GREY | 8 | ||
| WHITE | 9 | ||
| GOLD | 5% | ||
| SILVER | 10% | ||
Microcontrollers
What is a microcontroller?Â
A microcontroller is at its heart a programmable microchip that can be used to control sensors (heat, light, sound, etc.), motors and other electronic devices. It can be used as a stand-alone device or in connection with a computer. It is the heart of many small robots, remote control cars and almost all electronic devices (including most likely your toaster.)Â
When would someone use a microcontoller?Â
If you are thinking of making art that any sort smart element to it: recognizing a viewers presence, controlling motion of an object, having a small electronic device communicate with a computer or the internet, then a microcontroller might be what your looking for.
Where do I start?
There are many possible options of microcontrollers. Today many of these options are cheap, interface with cheap or free software, are easy to learn and there are large online communities to work with.
This section of the database will go over some of your options.Â
Arduino
This page focuses on the arduino microcontroller.
Atmel AVR
Introduction
This article started as some of my (Kelly Egan’s) notes from experimenting with AVR microcontrollers. I am not an expert on AVR chips. This information is just a result of my personal research. AVR is just one type of microcontroller available. Others include PIC, Propeller, Basic Stamp, Make Controller, Arduino, and Wiring I/O boards.
What is AVR?
AVR is a series microcontroller chips designed by Amtel. Like other microcontrollers it can be used as the computer ‘brain’ of small electronic devices and sensors. It can be used independently of a desktop or laptop computer or in communication with such a computer. Some chips allow direct ethernet connections and therefore can be independently connected to the Internet.
Why AVR?
Here are some of the reason I chose the AVR.
- Cost the chip, the programmer(device used to program the chip) and control board are all cheap compared to other options. PIC chips are also cheap but the programmers can be expensive, plus they have other drawbacks. Basic Stamps don’t require programmers but the modules cost from $50 to $100 dollars.
- OS X compatible The Basic Stamp is arguably the easiest to program on a Mac, but with a little effort an AVR chip can be as well. With a lot of effort a PIC might be able to be as well, but who wants to spend $300 on a programmer and find out it won’t work on your MacBook.
- Good support base From the research I have done there seems to be enough people using the AVR to make support fairly widespread. The Arduino, Make Controller and Wiring Boards are all based off AVR chips.
- Good marks the AVR also seems to receive good marks in the microcontroller community. While not as prolific as the PIC it is newer and so it seems it chips offer more power and ease of use. The fact that so many other microcontroller projects chose to base their systems off AVR seems a good sign as well.
External References
- Installing AVR toolchain — Besides actually programming the chips ladyada’s tutorial is the most complete.
- AVR C Programming Tutorial— Micah Carrick’s tutorial on programming AVR chips is one of the most detailed available on using avr-gcc and the avr c library (avr-libc).
attiny2313
One of the Atmel AVR series of microcontrollers. The attiny2313 is pin compatible with the at90s2313. It does not have any analog to digital converters but does have an analog comparitor which compares the voltage on two pins.
Examples:
- Hello world (blinking led)
- Basic input (button)
- Other example
Basic Stamp
This page will be the home for information on the basic stamp.
PIC
This page will talk about pic microcontrollers.
Motors and mechanics
This will cover adding motions, motors or other mechanics to a project.