Digital & Analog Inputs

Review Fundamental parts of an Arduino program are … Setting output types using pinMode. Declaring variables Can write a digital signal (0/1) to a pin using digitalWrite. Can read a digital signal (0/1) from a pin using digitalRead. – Must have a variable to store the value

IF, IF-ELSE, and IF-ELSE-IF if (someCondition) { // do stuff if the condition is true } if (someCondition) { // do stuff if the condition is true } else { // do stuff if the condition is false } if (someCondition) { // do stuff if the condition is true } else if (anotherCondition) { // do stuff only if the first condition is false // and the second condition is true }

Your turn Challenges: Complete in order 1.Push the button and have it display an LED pattern Fireworks! 2.Push the button and have it turn on alternate LEDs Button HIGH – Yellow Button LOW – Red 3. Push the button twice to turn on LED Need a COUNTER -- if you get to this stage, ask one of us for help

ANALOG INPUTS

Analog Signals What is an analog signal and how does it differ from a digital signal?

Analog Signals & Arduinos The Arduino can read an analog signal on one of the analog input pins. – analogRead The signal that can be read must be between 0 and 5 V. The Arduino converts the signal to a number between 0 and How many values are there for a digital signal? How many values are there for an analog signal on the Arduino?

Analog Input Program Time! We’re going to write a program that will turn on the Arduino’s LED when “threshold” value is reached. How: Potentiometer Use a Voltage Divider to change the voltage on the analog input pin. Use the Arduino to detect when the voltage has reached a certain level. Turn on the LED!

Analog Signal Detector Step 1 – Declare Variables: int inputPin = 0; // select the input pin for the potentiometer // ( can be 0 through 5). int ledPin = 13; // select the pin for the Arduino’s LED int inputValue = 0;// variable to store the value coming from // the voltage divider. Step 2 – Setup: void setup() { pinMode(ledPin, OUTPUT); //Declare the LED pin as an //output. } We do NOT have to declare the analog pin as an input. Why?

Analog Signal Detector Step 3 – The Loop: void loop() { inputValue = analogRead(inputPin); // Read the analog //input, what are // the possible values. if(inputValue > 511)// Check our threshold. { digitalWrite(ledPin, HIGH);// Turn on the LED. } else { digitalWrite(ledPin, LOW);// Turn off the LED. } }

Your turn Challenges: Complete in order 1.Design a program to make the LED flash at a speed dependent on the value on the analog input pin. 2.Turn on a number of LEDs that is proportional to the analog input value.