Category: Lecture

Lecture

In the lecture we spoke about the different ways that you can use an Arduino board to expand simple projects into more complex ones. We looked at different sensors and in particular I looked at a force sensitive resistor.

The link for this image of a FSR – Force-Sensing-Resistor.jpg (1847×1114) (elprocus.com)

Lab

We began the lab by using code for the Arduino that allowed for a sine tone to be created using a small speaker. The circuit that was used is included below and this is followed by the code that allowed us to create a sine tone with breaks in between.

//A sketch to demonstrate the tone() function
//Specify digital pin on the Arduino that the positive lead of piezo buzzer is attached.
const int piezoPin = 8;
void setup() {
}//close setup
void loop() {
/*Tone needs 2 arguments, but can take three
1) Pin#
2) Frequency - this is in hertz (cycles per second) which
determines the pitch of the noise made
3) Duration - how long the tone plays
*/
tone(piezoPin, 450);
delay(500);
noTone(piezoPin);
delay(500);
}

We went through many other commands that you can add to the code in order to create more advanced melodies. We made our own code that ascend up to a specific note and then decrease to another. The code included below is just that.

//A sketch to demonstrate the tone() function
//Specify digital pin on the Arduino that the positive lead of piezo buzzer is attached.
const int piezoPin = 8;
void setup() {
}//close setup
void loop() {
/*Tone needs 2 arguments, but can take three
1) Pin#
2) Frequency - this is in hertz (cycles per second) which
determines the pitch of the noise made
3) Duration - how long the tone plays
*/
for (int i=31; i<10000; i++) {
tone(piezoPin, i, 1000);
delay(10);
}

for (int i=10000; i>700; i--) {
tone(piezoPin, i, 10000);
delay(10);

}
}

Digital Oscillator

Code for digital oscillator

//CODE DigitalOSC
const int ledPin = 13; //variable to represent LED Pin
const int periodKnob = A0; //variable for knob pin (A0 = analog in pin 0)
int delayTime; //variable for the delay time
void setup() {
pinMode(ledPin, OUTPUT); //configure pin 13 as a digital output
}
void loop() {
//set delay time equal to the current value read on analog pin 0
delayTime = analogRead(periodKnob);
//map the analog read range from 0-1023 to 10000-1
//delayTime = map(delayTime, 0, 1023, 10000, 1);
digitalWrite(ledPin, HIGH); //set pin 13 to 5 volts
delayMicroseconds(delayTime); //pause program
digitalWrite(ledPin, LOW); //set pin 13 to 0 volts
delayMicroseconds(delayTime); //pause program
}
//

Lecture

Today we began by looking at the different types of sensors and actuators in the lecture.

A sensor – is a device that detects and responds to some type of input from the physical environment. The specific input could be light, heat, motion, moisture, pressure, or any one of a great number of other environmental phenomena. 

Lab

In the lab we used an Arduino to connect a push button and an LED together which would allow the button when pressed to switch on the LED, this then progressed into allowing the led to fade in and out.

Code

Below is the code used from the lab that allowed for the button to switch on the LED and keep it switched on until the button was pressed again.

const int LED = 13; // the pin for the LED
const int BUTTON = 7; // the input pin where the
// pushbutton is connected
int val = 0; // val will be used to store the state
// of the input pin
int state = 0; // 0 = LED off while 1 = LED on
void setup() {
pinMode(LED, OUTPUT); // tell Arduino LED is an output
pinMode(BUTTON, INPUT); // and BUTTON is an input
}
void loop(){
val = digitalRead(BUTTON); // read input value and store it
// check if the input is HIGH (button pressed)
// and change the state
if (val == HIGH) {
state = 1 - state;
}
if (state == 1) {
digitalWrite(LED, HIGH); // turn LED ON
} else {
digitalWrite(LED, LOW);
}
}

Arduino button switching on/off the LED

Arduino LED – Complete Tutorial – The Robotics Back-End (roboticsbackend.com)

There were several versions of the same code but all of them had different improvements as it was found that as the Arduino runs quicker than the time it takes for a human to press the button, it would sometimes flicker. Altering the code allowed for the Arduino to have time to process so now no flickering would occur with the LED.

Controlling light with pulse-width modulation

We then coded the Arduino board to allow an LED light to fade the light from high to low using this code below.

// Fade an LED in and out, like on a sleeping Apple computer
const int LED = 9; // the pin for the LED
int i = 0; // We'll use this to count up and down
void setup() {
pinMode(LED, OUTPUT); // tell Arduino LED is an output
}
void loop(){
for (i = 0; i < 255; i++) { // loop from 0 to 254 (fade in)

analogWrite(LED, i); // set the LED brightness

delay(10); // Wait 10ms because analogWrite // is instantaneous and we would // not see any change }

for (i = 255; i > 0; i--) { // loop from 255 to 1 (fade out)
analogWrite(LED, i); // set the LED brightness
delay(10); // Wait 10ms
}
}