There is an optional change that can be made to actually have the temperature readings affect the calculations for ping()

unsigned int ultrasoundValue;
unsigned long echo;

//TEMP = 172; // used if one wishes to feed temperature information in calculations for distance

unsigned int ping(){
pinMode(PingPin, OUTPUT); // Switch signalpin to output
digitalWrite(PingPin, LOW); // Send low pulse
delayMicroseconds(2); // Wait for 2 microseconds
digitalWrite(PingPin, HIGH); // Send high pulse
delayMicroseconds(5); // Wait for 5 microseconds
digitalWrite(PingPin, LOW); // Holdoff
pinMode(PingPin, INPUT); // Switch signalpin to input
digitalWrite(PingPin, HIGH); // Turn on pullup resistor
echo = pulseIn(PingPin, HIGH); //Listen for echo
ultrasoundValue = (echo / 58.138)*.39;

//IF one wishes to feed the temperature into this calculation, uncomment the following line, and comment out the previous line
// ultrasoundValue = (echo * TEMP)/25641;

return ultrasoundValue;
}

unsigned int Thermister(int RawADC) { //the value of RawADC should be the returned value of analogRead(THERMISTORPIN);
double Temp;
Temp = log(((10240000/RawADC) - 10000));
Temp = 1 / (0.001129148 + (0.000234125 * Temp) + (0.0000000876741 * Temp * Temp * Temp));
Temp = Temp - 273.15; // Convert Kelvin to Celcius

/*IF one wishes to feed the temperature into this calculation, uncomment the following line
TEMP = (Temp*.6 + 331.5)/20000; //for info on how this was found, check the data sheets*/

Temp = (Temp * 9.0)/ 5.0 + 32.0; // Convert Celcius to Fahrenheit
return Temp;
}

To make a long story short, I got the two Xbee units up & running using a "virtual wire". (As in the Arduino is just using the standard communication methods)

See the video:

The Arduino on the left (powered by the Mac), is commanding, via Xbee, the Arduino on the right (powered by the PC) to turn on/off the LED every second.

Midway through the video I unplug the transmitting Arduino, to show the effect it has on the receiving -- the light stops blinking.

See the extended entry for sketch code

~Zeb "Is not happy with Sparkfun Electronics right now" GrandPre

I was a little concerned the other design group (Solar House) that is using the Xbee units might interfere with our communication, so I created a unique network ID (which offers optional encryption). I gave the network the ID# 1337, for obvious reasons.

Here are the two Arduino's source code:

****************Transmitting Code***********

void setup()
{
Serial.begin(9600);
}

void loop()
{
Serial.print('H'); //instruction to turn LED ON -- but really could be anything
delay(1000);
Serial.print('L'); //instruction to turn LED OFF
delay(1000);
}

**************RECEIVING CODE*******************

int outputPin = 12;
int val;

void setup()
{
Serial.begin(9600);
pinMode(outputPin, OUTPUT);
}

void loop()
{
if (Serial.available()) {
val = Serial.read();

if (val == 'H') {
digitalWrite(outputPin, HIGH); //turn LED ON
}
if (val == 'L') {
digitalWrite(outputPin, LOW); //turn LED OFF
}
}
}

Download file

~Zeb

Fortunately, the sensors arrived, so I got to work on the first proximity sensor. I set up a really basic program that will basically sense if there is a change in distance. So in the video, if an object is placed in front of it (my hand), the red LED will flash. If the hand is removed it will flash again. Also, because it was too hard to quickly record, but the actual distance in inches is being streamed to my computer -- so far when it says 55 inches, it is pretty darn accurate

See the attached video.

Keep in mind, I threw this together rather quickly (notice how there are only 3 wires coming out of the Arduino) If there is concern about the sensitivity, I will be fine tuning it later.

Either way, thought it might build up a little excitement!

~Zeb

An important note is that this is 1 of 2 sensors that we may use.

**********************CODE***************************************************

// * Copyleft 2007 Jason Ch
unsigned long echo = 0;
int ultraSoundSignal = 9; // Ultrasound signal pin
unsigned long ultrasoundValue = 0;
int ledPin = 13;

void setup()
{
Serial.begin(9600);
pinMode(ultraSoundSignal,OUTPUT);
pinMode(ledPin, OUTPUT);
}

unsigned long ping(){
pinMode(ultraSoundSignal, OUTPUT); // Switch signalpin to output
digitalWrite(ultraSoundSignal, LOW); // Send low pulse
delayMicroseconds(2); // Wait for 2 microseconds
digitalWrite(ultraSoundSignal, HIGH); // Send high pulse
delayMicroseconds(5); // Wait for 5 microseconds
digitalWrite(ultraSoundSignal, LOW); // Holdoff
pinMode(ultraSoundSignal, INPUT); // Switch signalpin to input
digitalWrite(ultraSoundSignal, HIGH); // Turn on pullup resistor
echo = pulseIn(ultraSoundSignal, HIGH); //Listen for echo
ultrasoundValue = (echo / 58.138) * .39; //convert to CM then to inches
digitalWrite(ledPin, LOW);
return ultrasoundValue;
}
void loop()
{
int x = 0; //current distance
int x0 = 0; //previous distance
while(1){

x = ping();
if(((x+10)x0)){
digitalWrite(ledPin, HIGH); //there was a difference of +- 10 inches measurement, light it up
}
else{
digitalWrite(ledPin, LOW); //there wasn't a difference sensed, turn off light
}

x0=x; //set current to previous for next time
Serial.println(x);
delay(250); //delay 1/4 seconds.
}
}

*******************************************************************************

This initial prototype displayed the qualities of an active water surface that matched the poetic concept that I had in mind.

Ben Faga, an art student and UROP worked with me to prototype a series of rotating rods with sculpted, reconfigurable cams.

The responsive and fluid nature of this surface and the kinetic play of the video upon it were a perfect embodiment of the qualities that I associate with flux and flow.

This prototype enabled me to share the concept more effectively and led to an invitation by the Weisman Museum of Art to commission this as a site-specific work for the permanent collection.