Administrative issues

Arduino

• www.arduino.cc
  • based on Wiring which is based on Processing
  • what's the next thing? will it be based on Arduino, or on Wiring???
• cheap
• open source
• you can build it yourself
  • from a pre-made board
  • on a breadboard
• on some boards, you can change the microcontroller (ATmega8 or ATmega168)
• you can extend it upwards
  • simple breadboards
  • shields
• many types of boards
  • including a wireless Arduino BT (Bluetooth), quite expensive.
• we have 3 Arduino NG (ATmega8), and 3 Arduino Diecimila (ATmega168)
  • see practical serial communication, FTDI circuit on-oboard
    • ports > COM10 don't seem to work!
  • gets power from the USB, you can change that with a jumper if you need to give it more current
• The Arduino Guide
  • there are other sources of documentation even around the Arduino site. A bit messy.

Hardware layout

from the Arduino booklet or you can look at the board guide or this forum message.

• schematic, nothing mysterious/unexpected
• The L led must blink at reset/power-up
  • otherwise the board doesn't have a bootloader, so you can't program it
  • connected to digital pin 13
• RX and TX LEDs blink during programming
• Just one serial port
  • same as the programming serial port
  • also used for debugging
  • connected to pins 0 (RX) and 1 (TX) and to USB

Programming Arduino

• download the programming environment and see the environment guide
• reference
• tutorials
• how-to Windows, Mac
  • if you can't get it to work, see troubleshooting
  • in the Tools menu, check the Microcontroller and Serial port!
• programming practicalities
  • need reset before programming
  • you need to indicate the serial port you use
  • after reset or power-up, Arduino (the bootloader) waits for a while to be programmed
    • your application will start later!
  • program download takes longer time
  • generated microcontroller object code is large in size
    • (3 kB for a small program out of the 7kB available on the ATmega8)
    • probably because the standard libraries are downloaded each time? sounds inefficient
• the Arduino language
  • implemented in C
  • procedural C syntax, similar to procedural Java syntax
    • differences from Java/Processing
  • programs are called "sketches"
• Since most physical computing applications do a bit of setup then loop to check their sensors (polling), this is pre-programmed in Arduino
  • void setup()
    • setting pin modes (input, output) using pinMode()
    • setting the serial port using Serial.begin()
  • void loop()
• like in any C program:
  • you can define functions
  • you can use #define for constants
  • if(a=10) is legal and most often a programmer mistake (unlike in Java)
  • for, while, switch, etc
• Libraries available
  • SoftwareSerial does serial communication in software, on any pin

Debug

• just do serial output, Serial.println()
  • but this means that you can't do both debugging and serial communication unless the other party is instructed to ignore
• there is also printInteger(), printString()... but the Serial.print() and Serial.println() seem easier
• the serial communication can be read with any other program, not just the Arduino environment. You can e.g. use the Windows Hyperterminal, or the Mac Terminal.
  • just make sure you use the same baud rate in Serial.begin() and in your terminal program.
  • in the environment you can set the baud rate from a chooser.

Digital output

• digitalWrite()
• the blinking LED
• pin 13 has a resistor and is connected to the L LED so digital output on pin 13 doesn't need a LED
• the LEDs we have can actually be used without resistors and they'll blink brighter

Digital input

• digitalRead()
• source
• one can e.g. connect a IR motion detector
  • white to digital pin, red to power, black to ground
  • 220 Ohm between white and red

Analog input

• analogRead()
• source
• variable resistor between power and pin, another resistor between pin and ground
• uses a analog-digital converter (ADC) built in the microcontroller
  • measures voltage

Analog output (PWM= Pulse Width Modulation)

• analogWrite()
• can only be done on pins 9, 10, 11
• dimming LED source
  • simple LED connection from pin 11 to ground seems to work

Driving servos

• special library
• source

Event-based programming

• you can define digital events on 2 pins via interrupts
  • not analog (give me an interrupt when value is under X)
• source example
• attachInterrupt(pin-2, function, mode)
• function is a function name (should actually be &fucntion = the address of the function in strict C language)
• mode can be LOW, CHANGE, RISING, FALLING
  • if mode is LOW, interrupts keep comming as long as the pins stays on LOW voltage
• pin-2: pin 2 -> 0, pin 3->1. Only values 0 and 1 (pins 2 and 3) work for interrups
• detachInterrupt()
• still, there is no event queue like on Phidgets, no event details, no analog events, etc.

Other Arduino functions

• shiftOut(pin, clockPin, order, value) writes a byte synchronously (with clock)
• unsigned long pulseIn(pin, value) measures the length of a pulse waiting for Value (HIGH, or LOW)
• unsigned long millis() tells the number of milliseconds that passed since the board started last
• delayMicroseconds(us) finer than delay()
• functions for random generation, use randomSeed() first, then random()