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I’m a community programs manager who is skillful at building vibrant local and global communities and has a proven track record of driving engagement and fostering collaboration. I am committed to empowering students and individuals and achieving impactful results.
In this series, I will document my experience with the projects in the project book of the Arduino starter kit and the Arduino engineering kit.
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I am particularly excited about project 02 not only because it was named Spaceship Interface but also because this is the first project where we will write code for the Arduino Uno board. If you haven't gotten your Arduino IDE installed yet follow th...
In project 02, we wrote our first lines of Arduino code. In this project, we will not only be writing code, but we will also work with our first sensor, the temperature sensor.
The project description as written in the project's book;
You'll be using a temperature sensor to measure how warm your skin is. This component outputs a changing voltage depending on the temperature it senses. It has three pins: one that connects to the ground, another that connects to power, and a third that outputs a variable voltage to your Arduino. In the sketch for this project, you'll read the sensor's output and use it to turn LEDs on and off, indicating how warm you are. There are several different models of temperature sensors. This model, the TMP36, is convenient because it outputs a voltage that changes directly proportional to the temperature in degrees Celsius.
The Arduino software (IDE) comes with a serial monitor tool that enables you to report back results from the microcontroller. Using the serial monitor, you can get information about the status of the sensors and get an idea about what is happening in your circuit and code as it runs.
The breadboard and circuit schematics as drawn in the project's book;
We covered the structure of Arduino code in project 02, where we talked about the setup() and the loop() functions. We also dealt with variables and digital pins. In this project, in addition, we will be dealing with analog pins and constants.
Analog systems, unlike digital systems, which transmit information in either 0 or 1 format, transmit the information as electric pulses of different amplitude. The Arduino has a built-in Analog-to-Digital Converter (ADC). Analog pins A0-A5 have values that range from 0-1023 Constants are different from variables in the sense that they cannot change.
Let's run through the code below.
setup(), we use Serial.begin() to allow the Arduino to send messages via the Serial monitor. It takes two arguments Serial.begin(speed, config), the latter is optional. In this case, we're telling the Arduino to communicate at a rate of 9600 bits per second.for() loop to set the pins we connected to the LEDs, unlike project 02, where we defined each pin one after the other, here we set everything in the loop LOW, pin 2 to 4.loop(), we defined a variable sensorVal which stores the value of the sensorPin, which is our analog pin. Then, we use analogRead() to get the value from the analog pin.Serial.print() displays human-readable data on the serial monitor. It can display the value of a variable or of anything you type in quotation marks.
In this case, we're looking for the voltage value, making that the subject of the formula, we store the value in the variable named voltage. Then we print it out to the serial monitor.
Serial.println() this is different from the Serial.print() as it creates a new line.The code as written in the project's book:
const int sensorPin = A0;
const float baselineTemp = 25.00;
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
for(int pinNumber=2; pinNumber <5; pinNumber++){
pinMode(pinNumber, OUTPUT);
digitalWrite(pinNumber, LOW);
}
}
void loop() {
// put your main code here, to run repeatedly:
int sensorVal = analogRead(sensorPin);
Serial.print("Sensor Value: ");
Serial.print(sensorVal);
// convert ADC reading to Voltage
float voltage = (sensorVal/1024.0) * 5.0;
Serial.print(", Volts: ");
Serial.print(voltage);
Serial.print(", degrees C: ");
// convert the voltage to temperature in degrees
float temperature = (voltage - 0.5) * 100;
Serial.println(temperature);
if(temperature < baselineTemp+2){
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
}
else if(temperature >= baselineTemp+2 && temperature < baselineTemp+4){
digitalWrite(2, HIGH);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
}
else if(temperature >= baselineTemp+4 && temperature < baselineTemp+6){
digitalWrite(2, HIGH);
digitalWrite(3, HIGH);
digitalWrite(4, LOW);
}
else if(temperature >= baselineTemp+6){
digitalWrite(2, HIGH);
digitalWrite(3, HIGH);
digitalWrite(4, HIGH);}
delay(1);
}
The steps to upload the program to your board;
From the menubar, click tools;
Let's check out the Serial monitor:
If you weren't sure of your baselineTemp before you touch the sensor, the temperature reading is that of your environment, and you can update your baselineTemp and upload the code again.
Your body temperature is always higher than your environment; if you hold the sensor for a while, one or more LEDs should light up.
My body temperature was hot enough to make one LED light up.
I decided to use a 16x2 LCD to display the temperature and a Potentiometer to control the contrast on the LCD screen.
Something to note: The LCD is labeled from 1 to 16. In this diagram, one is at the bottom and 16 at the top.
Let's jump into the differences here.
lcd.print() to display content to the LCD screen. It works the same way as Serial.print(); the difference is that we're displaying to the LCD and the Serial Monitor, respectively.lcd.clear() so that each value stands alone on the screen.#include <LiquidCrystal.h>
LiquidCrystal lcd(12,11,5,4,3,2);
const int sensorPin = A0;
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
lcd.begin(16,2);
}
void loop() {
// put your main code here, to run repeatedly:
int sensorVal = analogRead(sensorPin);
Serial.print("Sensor Value: ");
Serial.print(sensorVal);
float voltage = (sensorVal/1024.0) * 5.0;
Serial.print(", Volts: ");
Serial.print(voltage);
Serial.print(", degrees C: ");
float temperature = (voltage - .5) * 100;
Serial.println(temperature);
lcd.print(temperature);
lcd.print(" degrees C");
delay(2000); //two seconds delay
lcd.clear();
delay(50);
}
After uploading your program, the temperature you see on display is the temperature of the environment. Place your finger over the sensor and observe the changes in the temperature values displayed on the screen.
