Touch Sensitive Audio Desk Trays- Arduino




After having completed my first Arduino project (which can be found here) I wanted to try and create something that had more of a practical use. My idea behind this project was a way of aiding the visually impaired.

By the end of this project you will have created some touch sensitive desk trays which use audio labels that are re-recordable.

Feel free to modify it and make it your own once you have completed these steps.

During this tutorial I have provided serveral links to Arduino’s own tutorials and more about Arduino can be found here.

Hovering over the image squares gives you more information.

Touch Sensitive Audio Desk Trays- Arduino




Total time to complete: 1.5 hours (you do not need to complete all of this in one sitting)

Please note that as always you will need a computer with USB capabilities to program your Arduino.

Step 1: Things you will need

Step 2: Touch sensitive pin with 1 LED

Step 3: Making touch sensitive with 3 LEDs

Step 4: Connecting up the trays

Step 5: Attaching the speaker

Step 6: Attaching the microphones

Step 7: Adding a recording button

Step 8: Finished product

Step 1: Things you will need:

Materials

  • Arduino Uno (£22.19)
  • 9 V Mains Power Supply (500 mA minimum, 2.1mm center-positive plug) (£6.72)
  • USB cable type A Male to type B Male (£8.93)
  • Solder (£0.89) – missing from images
  • Wire
  • 3 * Conductive Desk Trays (£15)

Circuit Components

  • mini push button (£3.20)
  • 3 * LED (£2.89 for 75)
  • 3 * 150 ohm resistor (£1.04 for 100) (colour code = brown, green, brown, gold)
  • 3* 1 Mohm resistor (£0.20 for 20) (colour code = brown, black , black , yellow, brown)
  • Female to Male jumper pins (£1.70)
  • Male to Male jumper pins (£5.99)
  • 8-ohm speaker with cable (£2.48)

Hardware

Tools – missing from images

  • Soldering Iron (£8.99)
  • Wire strippers (£2.68)
  • Small flathead screw driver (£2)

Total Cost

Materials : £53.73

Circuit Components: £17.50

Hardware: £11.60

Tools : £13.67

£96.50

Step 2: Touch sensitive pin with 1 LED

You will need:

  • 1 * LED
  • 5 * Male-Male Jumper Pins
  • 1 * 150 ohm resistor (colour code = brown, green, brown, gold)
  • 1 * 1 Mohm resistor (colour code = brown, black , black , yellow, brown)
  • Breadboard
  • Arduino
  • Arduino USB cable

If this is your first Arduino project or you don’t know how to set up a LED please look at step 2 and 3 here.

Attach the LED to pin 13 as in the Arduino Blink example.

To make the touch sensitive part we are going to use the CapacitiveSensor library.

The capacitiveSensor method toggles a microcontroller send pin to a new state and then waits for the receive pin to change to the same state as the send pin. A variable is incremented inside a while loop to time the receive pin’s state change. The method then reports the variable’s value, which is in arbitrary units.

We are going to use pin 7 as the send pin and pin 6 as the receive pin.
Connecting up the Capacitive Sensor:

  1. Connect pin 7 to the positive rail on the breadboard, this will allow us to use pin 7 for multiple sensors.
  2. Connect one end of the 1 Mohm resistor to pin 7 (using the positive rail)
  3. Connect the other end of the resistor to the receive pin ( pin 6)
  4. Connect the last jumper pin to the receiver pin (by connecting it on the same line on the breadboard). This will be the touch sensor.
  5. Make sure the Arduino/ Laptop is grounded. This can be done either by attaching your laptop to your charger while plugged in to the mains or by attaching a cable from Arduino ground to a water pipe ie. a radiator.

You are now ready to plug in the Arduino and upload the below programme. As you touch and let go of the touch sensor pin, the LED should switch on and off.

You may need to adjust groundHigh variable depending how sensitive you want your pin.

Touch Sensitive Audio Desk Trays- Arduino circuit

#include <CapacitiveSensor.h>
CapacitiveSensor sensor = CapacitiveSensor(7,6);  
int led = 13;
int groundHigh = 100;
void setup()                    
{
pinMode(led, OUTPUT); 
Serial.begin(9600);  
}
void loop()                    
{
long total =  sensor.capacitiveSensorRaw(3);
Serial.println(total);                  // print sensor output 
if(total > groundHigh){
digitalWrite(led, HIGH);  
}else{
digitalWrite(led, LOW);  
} 
}

Arduino Controlled Touch Sensitive Audio Desk Trays – Step #2(320×240) 9

 

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