Unlike pinMode(INPUT), there is no pull-downresistornecessary. An internal 20K-ohm resistor is pulled to 5V. This configuration causes the input to read HIGH when the switch is open, and LOW when it is closed. created 14 Mar 2012 by Scott Fitzgerald This example code is in the public d...
This example demonstrates the use of pinMode(INPUT_PULLUP). It reads a digital input on pin 2 and prints the results to the serial monitor. The circuit: * Momentary switch attached from pin 2 to ground * Built-in LED on pin 13 Unlike pinMode(INPUT), there is no pull-down resistor n...
If you disconnect the digital I/O pin from everything, the LED may blink erratically. This is because the input is "floating" - that is, it will randomly return either HIGH or LOW. That's why you need a pull-up or pull-down resistor in the circuit. 如果断开数字 IO 针脚,LED 会不...
pinMode函数 引脚模式选择,模式有INPUT(输入), OUTPUT(输出), INPUT_PULLUP(上拉输入,自动拉高电平) //GPIO FUNCTIONS #defineINPUT0x00 //输入 #defineINPUT_PULLUP0x02 //上拉输入 #defineINPUT_PULLDOWN_160x04// PULLDOWN only possible for pin16下拉输入仅适用于PIN16脚 #defineOUTPUT0x01 //输出 #...
example by Ryan Owens */// Store the Arduino pin associated with each inputconst byte PIN_BUTTON_LEFT = 2; // Select button is triggered when joystick is pressedconst byte PIN_BUTTON_RIGHT = 3;const byte PIN_BUTTON_UP = 4;const byte PIN_BUTTON_DOWN = 5;const byte PIN_BUTTON_SELECT ...
http://www.arduino.cc/en/Tutorial/InputPullupSerial This example code is in the public domain */ void setup() { //start serial connection Serial.begin(9600); //configure pin2 as an input and enable the internal pull-up resistor
the values of the other analog inputs, how close your hand is to the board, etc.). 假如模拟输入引脚没有连结就任何地方, analogRead() 的返回值也会 因为某些要素而颠簸(如其余模拟输入,你的手与主板靠的太近) Example 例子 int analogPin = 3; Can be used to light a LED at varying ...
{delay(1000);lcd.begin(16,2);Serial.begin(9600);pinMode(enroll, INPUT_PULLUP);pinMode(up, INPUT_PULLUP);pinMode(down, INPUT_PULLUP);pinMode(del, INPUT_PULLUP);pinMode(match, INPUT_PULLUP);pinMode(buzzer, OUTPUT);pinMode(indFinger, OUTPUT);digitalWrite(buzzer, LOW);if(digitalRead(en...
And in this example when I pressed the button the state rose to HIGH. Conclusion – Arduino INPUT_PULLUP recap In this tutorial you’ve seen how to properly use pull up and pull down resistors for your Arduino sensors, and when to use the INPUT_PULLUP option for the pinMode function. ...
数字引脚 0~15可以设置为 INPUT,OUTPUT 或者 INPUT_PULLUP 模式。引脚 16可以设置为INPUT,OUTPUT 或者 INPUT_PULLDOWN_16 模式。在启动时,引脚被配置为INPUT。 引脚同样可以提供其他功能,像串行,I2C,SPI。这些函数通常需要使用相应的库。下图为ESP-12模块的引脚图: ...