Course Notes – 26 Feb 08

Resources:

Class Resource Page – has long lists of local and mailorder places to buy things. Remember to ask here and on the blog to coordinate group orders, you can pay for overnight and split the cost several ways.

Techniques:

Charliplexing – driving a lot of LEDs with only a few pins. You don’t have to understand why it works, but it’s easy to set up and there are plenty of examples using Arduino.

LED drivers – simple chips that can be used to turn on and off a number of switches

LED multiplexers – another way to turn lots of LEDs on and off. I find these the easiest to understand and work with.

Interesting site

Hey guys, I was looking around one day for inspiration on a midterm / final idea when i came across this site called “makezine”.  I’m not sure if someone already linked to this site, but anyways, it’s got some really interesting stuff, not all of it’s arduino related but most of it includes a micro-controller.  Google brought me to page 33 of the blog, but you can start at page one:

Here’s the site, check it out if you need some inspiration.

http://blog.makezine.com/archive/diy_projects/33.html

Finally got the H-Bridge Working!

I have been messing around with a H-bridge to control my linear actuator. The H-bridge switches the negative and positive flows of electricity to be able to change the direction of the actuator. For example, the H-bridge allows me to spin a DC motor in forward and reverse or make the actuator move in or out. Cool stuff.

My initial problem was one of 2 things: 1) There was not a common ground between the arduino and external power source 2) I did not have the correct size capacitor. After I did both of these it worked! Unfortunately, after much excitement, I fried my H-bridge. I accidently let go of the ’switch wire’ I was using to control it and it contacted the H-Bridge and a lot of smoking and nasty smell ensued. I need to get a new H-bridge ASAP. (the joys of working with 24V DC power!)

I used the ITP tutorial to get this to work:

http://itp.nyu.edu/physcomp/Labs/DCMotorControl

(The schematic and code that I used can be found on in this tutorial)

I also used an old architectural Roboctic handout from Mark:

http://www.architecturalrobotics.org/archrobots_handout3.pdf

Solenoid working! Yay!

Finally got a solenoid working, used a TIP 3055 transistor. linked it up with a 3V buzzer to be both activated by a rangefinder on a 2 second loop script. Here’s a schematic, a script, and a video:

int buzzer = 13;                    //buzzer set to digital 13
int rangeFinder = 0;                //rangefinder set to analog 0
int solenoid = 8;                   //solenoid set to digital 8
int val;

void setup ()
{
  Serial.begin (9600);              //serial library set up for troubleshooting
  pinMode (buzzer, OUTPUT);         //buzzer set to output
  pinMode (rangeFinder, INPUT);     //rangefinder set to input
  pinMode (solenoid, OUTPUT);       //solenoid set to output
}

void loop ()
{
  val = analogRead (rangeFinder);   //set definition for "val"
  Serial.print("switch input: ");
  Serial.println(val);
    if (val  50)                    //if object is far...
    {
	digitalWrite(buzzer, LOW);   //do nothing
    	digitalWrite(solenoid, LOW);
    }
}