ARDUINO PINS:

Please note that the pin numbering below follows the pin numbering of the Arduino board. They do NOT follow the pin numbering of the Atmega 8 microcontroller. Also see the Arduino Hardware Diagram and the Atmega8 (pdf) [some of you might have newer versions of the Arduino board, that use the Atmega 168 microcontroller].

Digital I/O: pin 0-13:

• 0-1: internally used for serial communication (program Arduino via USB); maybe used for external serial communication when not being programmed. However, external devices need to be disconnected during programming. [solution to problem: use software serial].
  
• 2-8: general I/O pins. Like all I/O pins, these may be defined as either input or output pins.
  
• 9-11: PWM pins. May also be used as standard I/O pins.
  
• 12: general I/O.
  
• 13: output pin. Internally wired to LED. May be connected to other components but must be used as output pin.
  
  

Analog I/O:

• 0-6: These pins have the same numbering as the digital pins, but are located at a different port. A different software function is used in order to write to these ports. These pins may be used as analog input pins (used for sensors for example or for any other variable analog input). They can also effectively be used as digital input or output pins.

Power, Ground, AREF:

• GND: The Arduino provides 3 GND pins. All the grounds are internally connected and should be connected to the ground of your circuity as well.
• +5V: When powered through the USB cable or a power adaptor, this pin provides 5V. This pin may also serve as an input pin for +5V to power the board.
• +9V: This is an input pin and may be used to power the board externally from a battery (for example).
• AREF: Is used to change the resolution of analogue to digital convergence. We won't use this function in this workshop. Instead we will do the same thing by re-writing the wiring.c source file, when using the Ozone sensor. (not for CO).
  
  THE ARDUINO MAY BE POWERED IN 3 DIFFERENT WAYS:
  1) Through the USB cable. This is particulary handy when programming the device.
  2) Through and external power supply, using the power supply connector on the Arduino board.
  3) Through batteries or external power supply using the +5V or +9V pins on the Arduino.
  
  In each case, you have to make sure that the jumper located next to the USB connector on the Arduino board is set to the correct position (USB power vs external power).

OTHER:

• FTDI: Is a chip that converts serial data to a USB readable datastream and vice versa.
• Power indicator LED: Lights up when power is applied to Arduino board, (turned "on").
• Reset Button: Used to reset Arduino board.