As a Final Project

It's great being a student, isn't it? 

Here's my final project, as written for my instructor:

Anita Giraldo

ENT1280

Description of Semester Project

Title: Sound unit for installation "Steel Ice & Stone"

Description: For my upcoming installation, I require a self-contained, free-standing sound unit that reacts to viewers in an exhibition space by 

1. playing a sound byte stored on a chip within it and

2. sending a signal to another sound unit in a remote location within the exhibition space for it to play the sound byte contained on the chip within it.

Implementation: The unit requires three inputs, all sensors:

1. Two sense the presence of a viewer in close proximity

2. one senses a signal from another sound unit

The unit has three outputs:

1. Two outputs are speakers that play back the two sound bytes from chips on the units

2. One sends a signal to another sound unit in a remote location within the exhibition space.

In addition, the unit must:

1. turn on and off

2. have controls to modulate the sensitivity of the sensors

3. have controls to modulate the loudness of the output (amplifiers)

4. be battery operated

5. be fully modular.

An old schematic from an engineer in OH

I had gotten this schematic from a really nice guy in OH who has responded to an email. I was going to contract him to build the sound unit, but discovered the Arduino instead.

Here's what he had come up with:

What could the Arduino be used for?

Perhaps it could:
a) Be used as a timer: IT would run for so may seconds until it turned of for so many seconds and then re-turn itself on.....
b) It could delegate different signals to the outputs

c) Reply the argument in a series of if--then statements.

Playing games with Calibration sketch

Below is the code to an Arduino sketch, Calibration. I'd use this to calibrate the sensitivity of the input sensors and perhaps the output signal to another piece. My questions are in BLUE.


Calibration

Demonstrates one technique for calibrating sensor input.  The
sensor readings during the first five seconds of the sketch
execution define the minimum and maximum of expected values
attached to the sensor pin.

The sensor minimum and maximum initial values may seem backwards.
Initially, you set the minimum high and listen for anything 
lower, saving it as the new minimum. Likewise, you set the
maximum low and listen for anything higher as the new maximum.

The circuit:
* Analog sensor (potentiometer will do) attached to analog input 0
* LED attached from digital pin 9 to ground

created 29 Oct 2008
By David A Mellis
Modified 4 Sep 2010
By Tom Igoe

http://arduino.cc/en/Tutorial/Calibration

This example code is in the public domain.

*/


// These constants won't change:
const int sensorPin = A0;    // pin that the sensor is attached to
const int ledPin = 9;        // pin that the LED is attached to
                                     // THE LED WOULD IN TURN LEAD TO THE 
                                        PLAYBACK CHIP

// variables:
int sensorValue = 0;           // the sensor value
int sensorMin = 1023;        // minimum sensor value
                                              //  HOW IS THIS VALUE ARRIVED TO?
int sensorMax = 0;           // maximum sensor value
                                    



void setup() {
 // turn on LED to signal the start of the calibration period:
 pinMode(13, OUTPUT);
 digitalWrite(13, HIGH);


 // calibrate during the first five seconds 
 // DOES THIS MEAN THAT I ONLY HAVE 5 SECONDS TO CALIBRATE THIS? while (millis() < 5000) {
   sensorValue = analogRead(sensorPin);


   // record the maximum sensor value
   // HOW IS THIS DONE?   if (sensorValue > sensorMax) {
     sensorMax = sensorValue;
   }


   // record the minimum sensor value
   // HOW IS THIS DONE?   if (sensorValue < sensorMin) {
     sensorMin = sensorValue;
   }
 }


 // signal the end of the calibration period
 digitalWrite(13, LOW);
}


void loop() {
 // read the sensor:
 sensorValue = analogRead(sensorPin);


 // apply the calibration to the sensor reading
 sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 255);


 // in case the sensor value is outside the range seen during calibration
 sensorValue = constrain(sensorValue, 0, 255);


 // fade the LED using the calibrated value:
 analogWrite(ledPin, sensorValue);
}

Programming

Other than the hardware and the outside pieces, the issue remains of how to program it.

From the Arduino app and under file, the Arduino could be programmed to be the timer, turn the unit on and off and calbrate the sensor. 

Switches

The ON/OFF switch could be a pressure(push button) or toggle switch. The button switch may be effective if tied to the sensor's sensitivity (see diagram below).

The straight push-button switch may not be good in case the viewers can manipulate the controls of the installation, turning it on and off (unless a timer is used).

However, a toggle switch, which can also be manipulated, breaks too easily.

Or, in the case of the all the switches, perhaps a code operated switch would be the way to go, or the suggested tool-operated switch that is manipulated by a screw-driver.

Switch Plate

Original switch plate schematic with digital sliders and indicators, shown. Rather clean design; wondering if it can still work.

Sensor Ideas

a) Does a sensor exist that detects viewers through the piece--which consists of a piece of linen with a photo laminated to it?
b) What kind of sensor picks up a transmitted signal from another sensor and how is this calibrated? Would sonar work in this case, leading to the question below:
c) What kind of a signal must the unit transmit? Is it audible?

SMV sensor with the plug.

Other Battery Questions

Are there different types of batteries other than the standard 9V?

http://www.batterydepot.com

has so many to look at, which one is the type that I'd need?

And, what is power needed for?
a) LED indicators: are they needed? In SMV the LED indicators which ate up a lot of battery life were used to calibrate the sensors. Perhaps the sensors could be calibrated without the use of an LED. Or, perhaps the LEDs could be turned off after the sensors have been calibrated.
b) Amplifiers and Speakers: I suspect the bulk of the power is going to be needed to bring the sound out of the units and make them loud enough to hear in the space. As was pointed out to me, without sufficient power, the amp might only be able to play the chip once.
c) The power to run the actual unit. I have no idea how much power this would need.

What about a timer?

A timer could be set to turn the unit on and off so no technicians would be needed to turn the installation on or off. or, would the power needed to run the timer cancel itself out?

Wireless IR Sensor?

Nyko Wireless Sensor Bar - IR sensor

$7 online

Back of the piece

Stretcher bars with unit and speakers affixed.

How to power the Unit?

With the sound unit on SMV, batteries were a constant worry. In Brooklyn, where the units only ran for six hours, two days a week, the batteries had to be changed twice during the installation's six week run.

Further, to power the speakers I'm thinking of for SIS, I am going to need a power source that will hold up. The idea of wires running down the piece are less a consideration than last time since the pieces are suspended and the possibility of viewers touching the pieces might result in a shock. Besides, they're unsightly.

The burning questions:
• Is there a battery that lasts longer and still fits in the required depth of 1.5 inches? How long does its power last?
• Is its power storage easily measurable and able to be indicated, so that batteries can be changed before they run out?

Formal Treatment of the Sound Unit for the Nine-Piece Installation, Steel Ice & Stone

For my upcoming installation, I plan to develop an embedded sound unit to play sound from each of the nine pieces.

Each sound unit must react to the presence of viewers in three ways:
• It must detect the presence of a viewer within three feet of its accompanying sensor and play sound from a chip/amplifier/speaker when the viewer crosses it.
• It must have the ability to transmit, to another piece in the exhibition space, a signal of the presence of a viewer so it can play back sound.
• it must play back sound from another chip in the unit when it receives a signal from another piece.

While the above characteristics are expected to go through many design phases and modifications, there are some firm requirements:
• It requires an On/Off switch or a timer to save battery pawer
• It requires a power source not dependent on an outlet or have other wires visible in the exhibition space: that is, it requires battery operation
• It requires modulators and corresponding indicators so that the sensitivity of the sensors and the loudness of the sound can be controlled from a panel easily accessible on the piece

Other requirements:
 • Modularity: The breadboard, sensors, speakers and switches being free-standing, easily-assembled (snap-on/snap-off) units allows interchangeability for ease in installation of the units and in the event of breakage.
• While the size of the unit could measure as large as 8 x 10 inches, the depth of the unit cannot exceed 1.5 inches.

Thin speakers

AliBaba, an international trader, shows speakers for $ 200-500 when buying 100 sets from a manufacturer in Korea.

IMPEX COREA
21 Century City# 1405, Daeyeon-Dong, Nam-Gu
Busan, South Korea  600-822
82-51-4610705 Tel.


Looking at the illustration, it seems to be what I'm looking for; It fits behind a picture (how does the sound get out?) The 100 units is unacceptable, however. 


This can wait until later.

Ideas on Interactivity

Keeping the sound clean and simple is one thing, but will it make sense or sound like noise?
Observations by colleagues have added a new dimension to the piece: considering a better speaker so the sound is better transmitted.
Since the sound is neither music nor spoken word, and I'm planning for it to be multi-directional, it was recommended to me to research and possibly use a thin honey-comb speaker inside the piece which gives superior sound but, I can imagine, is quite expensive.

Moving right along

The electronics are what's taking center stage right now. Working with an instructor at City Tech, I've started a map-out of the sound unit using the Arduino as the micro controller to run it all. Over the next few days, I'll be back-posting the developments of the class, in addition to URL's of supplier websites, the Arduino forum and more.
A schematic has been drawn, and will be posted soon.