Skills Dev II - Lulin Shan
Made by Lulin Shan
Made by Lulin Shan
Created: November 14th, 2021
I learned and practiced how to use inputs (button, switch, and potentiometer) and sensors (photoresistor and FSR). For the exercise of combining sensors and inputs, I made a connected sensor device that reminds me to pour the boiled water in the kettle to the thermos.
Combine a switch and potentiometer. The switch should turn on and off the light while the potentiometer will fade up and down the light (but only when it’s on).
I wired a button to the circuit created in the tutorial “using a potentiometer”. I started with reusing the code in that tutorial and defined a new pin that I would place a button on. I reorganized the code related to analog readings/values to the if (buttonState == LOW) condition. Following the 3 step-by-step tutorials is really helpful and it makes the practice exercise less daunting!
// define a pin that I'll place pot on
int potPin = A5;
// create a variable to hold the pot reading
int potReading = 0;
// define a pin I'll place an LED on
int ledPin = D2;
// create a variable to store the LED brightness
int ledBrightness = 0;
//define a pin I'll place a button on
int buttonPin = D3;
void setup() {
// for input, I define the pushbutton as an input-pullup
// this uses an internal pullup resistor to manage consistent reads from the device
pinMode( buttonPin, INPUT_PULLUP ); // sets pin as input
// set up the LED for output
pinMode( ledPin, OUTPUT );
// create a cloud variable of type integer
// called 'light' mapped to photoCellReading
Spark.variable( "pot", potReading );
}
void loop() {
// find out if the button is pushed or not by reading from it
int buttonState = digitalRead( buttonPin );
// when the button is pushed, we will get a LOW signal
// when the button is not pushed, we'll get a HIGH
// set the LED on or off
if( buttonState == LOW )
{
// turn the LED on
digitalWrite ( ledPin, HIGH );
// use analogRead to read the potentiometer reading
// This gives us a value from 0 to 4095
potReading = analogRead( potPin );
// map this value into the PWM range (0-255) and store as the led brightness
ledBrightness = map( potReading, 0, 4095, 0, 255 );
// fade the LED to the desired brightness
analogWrite( ledPin, ledBrightness );
// wait 1/10th of a second and then loop
delay(100);
}else{
// otherwise, turn the LED off
digitalWrite( ledPin, LOW );
}
}// define a pin that we'll place the photo cell on
// remember to add a 10K Ohm pull-down resistor too
int photoCellPin = A0;
// create a variable to hold the light reading
int photoCellReading = 0;
// define a pin we'll place an LED on
int ledPin = D2;
// create a variable to store the LED brightness
int ledBrightness = 0;
void setup() {
// set up the LED for output
pinMode( ledPin, OUTPUT );
// create a cloud variable of type interger called 'light' mapped to photoCellReading
Particle.variable("light", &photoCellReading, INT);
}
void loop() {
// use analogRead to read the photo cell reading
// This gives us a value from 0 to 4095
photoCellReading = analogRead( photoCellPin );
// map this value into the PWM range (255-0) and store as the led brightness
ledBrightness = map( photoCellReading, 0, 4095, 255, 0 );
// fade the LED to the desired brightness
analogWrite( ledPin, ledBrightness );
// wait 1/10th of a second and then loop
delay(100);
}// define a pin that we'll place the photo cell on
// remember to add a 10K Ohm pull-down resistor too
int photoCellPin = A0;
// create a variable to hold the light reading
int photoCellReading = 0;
// define a pin we'll place an LED on
int ledPin = D2;
// create a variable to store the LED brightness
int ledBrightness = 0;
void setup() {
// set up the LED for output
pinMode( ledPin, OUTPUT );
// create a cloud variable of type interger called 'light' mapped to photoCellReading
Particle.variable("light", &photoCellReading, INT);
}
void loop() {
// use analogRead to read the photo cell reading
// This gives us a value from 0 to 4095
photoCellReading = analogRead( photoCellPin );
// find out if light levels are below 1000
// set our LED on or off
if ( photoCellReading < 1000){
ledBrightness = 255;
}else {
ledBrightness = 0;
}
// fade the LED to the desired brightness
analogWrite( ledPin, ledBrightness );
// wait 1/10th of a second and then loop
delay(100);
}
I like hot drinks when I’m working at home. I have a thermos that helps keep boiled water warm for a longer time, which saves the waiting time whenever I want a cup of hot drink. However, I often forget to pour the boiled water into the thermos before it gets cold:(
I hope to design a connected sensor device that reminds me to pour the boiled water in the kettle to thermos.
// Define a pin that I'll place the FSR on, remember to add a 10K Ohm pull-down resistor too.
int fsrPin = A0;
// Create a variable to hold the FSR reading
int fsrReading = 0;
// Define a pin I'll place an LED on
int ledPin = D2;
// Create a variable to store the LED brightness.
int ledBrightness = 0;
// Define a pin I'll place a switch on
int switchPin = D3;
void setup()
{
// for input, I define the switch as an input-pullup
// this uses an internal pullup resistor to manage consistent reads from the device
pinMode( switchPin, INPUT_PULLUP ); // sets pin as input
// Set up the LED for output
pinMode(ledPin, OUTPUT);
// Create a cloud variable of type integer called 'force' mapped to fsrReading
Particle.variable("force", &fsrReading, INT);
}
void loop()
{
// find out if the switch is thrown to the wired terminal ot not or not by reading from it
int switchState = digitalRead( switchPin );
// when the switch is thrown to the wired terminal, we will get a LOW signal
// when the button is thrown to the unwired terminal, we'll get a HIGH signal
if( switchState == LOW )
{
// Use analogRead to read the fsr reading
// This gives us a value from 0 to 4095
fsrReading = analogRead(fsrPin);
// find out if pressure levels are below 3000
// set our LED on or off
if ( fsrReading < 3000){
ledBrightness = 0;
}else {
ledBrightness = 255;
}
// fade the LED to the desired brightness
analogWrite(ledPin, ledBrightness);
// wait 1/10th of a second and then loop
delay(100);
}else{
// otherwise, turn the LED off
digitalWrite( ledPin, LOW );
}
}
It would be helpful to measure the pressure from the kettle with 0.5L water. Due to the size and shape of FSR, it was difficult for me to place the FSR under the center of the kettle base to measure the actual pressure. For this exercise, I set the threshold as 3000 for testing purpose.
I would like to use a temperature sensor to measure the water heat. For example, if the water temperature is more than 80 °C and the switch is on, turn the LED on.
This week’s tutorials helped me become more familiar with using inputs and sensors. I also became more comfortable in wiring and coding. I found it challenging to create a circuit on the breadboard from scratch. For this exercise, I referred to Fritzing circuit diagram in tutorials as a starting point, then add a second component into the mix. This approach smoothed the wiring progress a lot.
If I were to do it again, I would use a temperature sensor that tells me about the water in the electric kettle is warm. Additionally, it would be great if the LED can be placed on my desk. Otherwise, this connected device would not help me a lot if the LED is set by the kettle on the kitchen counter.