通过 Arduino UNO输出高电平点亮LED。 注意LED最大承载电压约为2V，10ma~15ma，需要串联一个电阻100R-200R左右都可以。一端连接。GND或者，一端连接输出端子。 /* Input Pull-up Serial
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 necessary. 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 domain.
http://www.arduino.cc/en/Tutorial/InputPullupSerial */
void setup() { //start serial connection Serial.begin(115200); //configure pin 2 as an input and enable the internal pull-up resistor //pinMode(2, INPUT_PULLUP); pinMode(8, OUTPUT);
}
void loop() { //read the pushbutton value into a variable //int sensorVal = digitalRead(2); //print out the value of the pushbutton //Serial.println(sensorVal);
// Keep in mind the pull-up means the pushbutton’s logic is inverted. It goes // HIGH when it’s open, and LOW when it’s pressed. Turn on pin 13 when the // button’s pressed, and off when it’s not: //if (sensorVal == HIGH) { // digitalWrite(13, LOW); //} else { digitalWrite(8, HIGH); delay(500); digitalWrite(8, LOW); delay(500); //} }