查看“第三课--按钮控制的LED开关”的源代码

{{Language|第三课--按钮控制的LED开关}}
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==Objective==
The first two experiments showed you how to use software to control the LED directly. If we add a button, 
to control the LED light, then realize the combination of hardware and software.
Actually that two experiment use Microduino I/O port as the output to control the LED, if want to use the button,
how to monitor the input signal of the button?
Today we will take button as an example to show how to use the Microduino as the input.


==Equipment==
*'''[[Microduino-Core]]'''
*'''[[Microduino-FT232R]]'''
*Other hardware equipment
**Breadboard Jumper            one box   
**Breadboard  	               one piece  
**LED Light-emitting diodes    one 
**220ohm resistor 	           one 
**Button                       one  
**USB Data cable               one

==Button==
*Button principle
[[File:第三课-按键原理.jpg|600px|center|thumb]]
If use this wrap button making PCB, if bad wiring, it has two pairs of pins available always conduction as a conductor wiring.

*Button connection
[[File:第三课-按键接法.jpg|600px|center|thumb]]

==Experimental schematic==
[[File:第三课-原理图.jpg|600px|center|thumb]]
Using external pulldown resistor, when didn't press, it is low "0", press for high.


==Program==
*LED display button value

<source lang="cpp">
const int buttonPin = 2;     // Define button input pin
const int ledPin =  13;     //Define LED pin
int buttonState = 0;        //Initialize the button value
void setup() {
  pinMode(ledPin, OUTPUT);    //Set the LED pin as output    
  pinMode(buttonPin, INPUT); //Set button pin as intpu    
}
void loop(){
  buttonState = digitalRead(buttonPin);//Read the value from the buttonPin
  if (buttonState == HIGH) {     
    digitalWrite(ledPin, HIGH); //If the button input signal is high, the LED will light (LED connect method is that anode connects control pin, cathode connects GND)
  } 
  else {
    digitalWrite(ledPin, LOW); //LED goes out
  }
}
</source>

*LED voltage flip
<source lang="cpp">
const int buttonPin = 2;     // Define button input pin
const int ledPin =  13;     

int buttonState = 0; 
boolean led;         //Define LED as boolean（true or false）
void setup() {
  pinMode(ledPin, OUTPUT);      
  // pinMode(buttonPin, INPUT); //Set the button pin as input     
  pinMode(buttonPin, INPUT_PULLUP);//Set button pin as interanl pull-up input    
}
void loop(){
  buttonState = digitalRead(buttonPin);
  if (buttonState ==HIGH) //Use the external pull-down, because the initial state is low, only the press is high, the press was flipped, or not it will blink.
  {  
    delay(200);                     //Short time delay, stabilization
    // delay(1000);               //Long time press
    // if (buttonState == LOW)  //Check still is low
    led=!led;                   //LED state flip
  } 
  digitalWrite(ledPin, led);  
}
</source>
This experiment should be noted the button anti-shake, you can adjust the delay time, 
or at both ends of the input signal plus a 104 capacitor, then voltage signal does not mutant.
The detailed button anti-shake information, please refer to：http://www.geek-workshop.com/thread-74-1-1.html
===digitalRead（）usage===
Read a Pin's value and return HIGH or LOW.

==Result==
*Program 1：LED display input button value. High value will light LED, or Put out the LED.
*Program 2：Each time you press the button, led voltage flipping once, pay attention to button anti-shake.
==Video==
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