# Theory and Practice of Tangible User Interfaces

### Announcements

November 24, 2007
Reading for November 27th, are now posted. Enjoy!

October 2, 2007
To upload your thoughtless acts, create a new assignment page like any other lab. You'll see "Thoughtless Acts" listed as one of the assignment options.

May 24, 2008
This site has been archived and is no longer editable. Stay tuned for the next version, coming in the fall!

# [Crawler on the WATER]

Project Members:
Sheng-Ying Pao

Description

How about making a crawler on the water???
I built a boat with the servo motor.
Let's row the boat!!!

` `
Gently down the stream.
Merrily, merrily, merrily, merrily,
Life is but a dream.

`  `
`  `

## Components

• 1 potentiometer
• 1 servo motor
• 1 plastic food container
• 1 chopstick (connecting 2 paddles to the servo motor)
• 1 hand-drawn mini flag with my personal icon
• 1 cotton bud (pole)
• 1 can lid (base for the servo motor)
• 1 basin with water
• lots of tape
• 1 Arduino board
• several wiring

## Code

```/*
* Servo with Potentiometer control
* Theory and Practice of Tangible User Interfaces
* October 11 2007
*/

int servoPin = 7;      // Control pin for servo motor
int potPin   = 0;      // select the input pin for the potentiometer

int pulseWidth = 0;    // Amount to pulse the servo
long lastPulse = 0;    // the time in millisecs of the last pulse
int refreshTime = 20;  // the time in millisecs needed in between pulses
int val;               // variable used to store data from potentiometer

int minPulse = 500;   // minimum pulse width

void setup() {
pinMode(servoPin, OUTPUT);  // Set servo pin as an output pin
pulseWidth = minPulse;      // Set the motor position to the minimum
Serial.begin(9600);         // connect to the serial port
}

void loop() {
val = analogRead(potPin);    // read the value from the sensor, between 0 - 1024

if (val > 0 && val <= 999 ) {
pulseWidth = val*2 + minPulse;  // convert angle to microseconds

Serial.print("moving servo to ");
Serial.println(pulseWidth,DEC);

}
}

// called every loop().
// pulse the servo again if rhe refresh time (20 ms) have passed:
if (millis() - lastPulse >= refreshTime) {
digitalWrite(servoPin, HIGH);   // Turn the motor on
delayMicroseconds(pulseWidth);  // Length of the pulse sets the motor position
digitalWrite(servoPin, LOW);    // Turn the motor off
lastPulse = millis();           // save the time of the last pulse
}
}```
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