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arduino:arduino_crash_course:basic_interaction

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arduino:arduino_crash_course:basic_interaction [2012/11/03 21:12] – [Polling versus interrupts] mithatarduino:arduino_crash_course:basic_interaction [2012/11/12 04:36] – mithat
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 The following examples use polling to determine the state of a switch. If the switch is pressed, Arduino will turn an LED on. If it is not pressed, it will turn the LED off. The following examples use polling to determine the state of a switch. If the switch is pressed, Arduino will turn an LED on. If it is not pressed, it will turn the LED off.
  
-==== Using external pulldown resistors ====+==== With external pulldown resistors ====
 The following example requires **pulldown resistors** on the input switch. The following example requires **pulldown resistors** on the input switch.
  
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 int pushButtonPin = 2;  // connect the push button to digital pin 2 int pushButtonPin = 2;  // connect the push button to digital pin 2
 int ledPin = 13;        // connect the LED to pin 13 int ledPin = 13;        // connect the LED to pin 13
 +int buttonState;        // stores current button state 
  
 void setup() { void setup() {
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 void loop() { void loop() {
-  int buttonState = digitalRead(pushButtonPin);  // read the input pin+  buttonState = digitalRead(pushButtonPin);  // read the input pin
  
     // set LED state accordingly     // set LED state accordingly
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 int pushButtonPin = 2;  // connect the push button to digital pin 2 int pushButtonPin = 2;  // connect the push button to digital pin 2
 int ledPin = 13;        // connect the LED to pin 13 int ledPin = 13;        // connect the LED to pin 13
 +int buttonState;        // stores current button state 
  
 void setup() { void setup() {
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 void loop() { void loop() {
-  int buttonState = digitalRead(pushButtonPin);  // read the input pin+  buttonState = digitalRead(pushButtonPin);  // read the input pin
   digitalWrite(ledPin, buttonState);             // turn the LED on or off   digitalWrite(ledPin, buttonState);             // turn the LED on or off
   //delay(1);        // delay in between reads for stability (?)   //delay(1);        // delay in between reads for stability (?)
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 int pushButtonPin = 2;  // connect the push button to digital pin 2 int pushButtonPin = 2;  // connect the push button to digital pin 2
 int ledPin = 13;        // connect the LED to pin 13 int ledPin = 13;        // connect the LED to pin 13
 +int buttonState;        // stores current button state 
  
 void setup() { void setup() {
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 </file> </file>
  
-==== Using internal pullups ====+==== With internal pullup resistors ====
  
 Using extenal resistors as part of switch state detection is so common that the microchip that is at the heart of the Arduino has built-in pullup resistors that can be turned on manually. Internal pullup resistors can be enabled with: Using extenal resistors as part of switch state detection is so common that the microchip that is at the heart of the Arduino has built-in pullup resistors that can be turned on manually. Internal pullup resistors can be enabled with:
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 int pushButtonPin = 2;  // connect the push button to digital pin 2 int pushButtonPin = 2;  // connect the push button to digital pin 2
 int ledPin = 13;        // connect the LED to pin 13 int ledPin = 13;        // connect the LED to pin 13
 +int buttonState;        // stores current button state 
  
 void setup() { void setup() {
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 void loop() { void loop() {
-  int buttonState = digitalRead(pushButtonPin);  // read the input pin+  buttonState = digitalRead(pushButtonPin);  // read the input pin
  
   // set LED state accordingly   // set LED state accordingly
-  // note the inverted logic+  // becasue we are using pullup resistors, the logic is inverted; 
 +  // in other words, pressed produces LOW, un-pressed produces HIGH.
   if (buttonState == LOW)        // if the button is pushed   if (buttonState == LOW)        // if the button is pushed
     digitalWrite(ledPin, HIGH);  // turn the LED on     digitalWrite(ledPin, HIGH);  // turn the LED on
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 int pushButtonPin = 2;  // connect the push button to digital pin 2 int pushButtonPin = 2;  // connect the push button to digital pin 2
 int ledPin = 13;        // connect the LED to pin 13 int ledPin = 13;        // connect the LED to pin 13
 +int buttonState;        // stores current button state 
  
 void setup() { void setup() {
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 void loop() { void loop() {
-  int buttonState = !digitalRead(pushButtonPin);  // read the input pin +  buttonState = digitalRead(pushButtonPin);  // read the input pin 
-  digitalWrite(ledPin, buttonState);              // turn the LED on or off+  
 +  // set LED state accordingly 
 +  // becasue we are using pullup resistors, the logic is inverted; 
 +  // in other words, pressed produces LOW, un-pressed produces HIGH. 
 +  digitalWrite(ledPin, !buttonState);        // turn the LED on or off
 } }
 </file> </file>
arduino/arduino_crash_course/basic_interaction.txt · Last modified: 2017/12/06 01:05 by mithat
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