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49 lines
1.3 KiB
C++
49 lines
1.3 KiB
C++
/*
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Input Pull-up Serial
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This example demonstrates the use of pinMode(INPUT_PULLUP). It reads a
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digital input on pin 2 and prints the results to the Serial Monitor.
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The circuit:
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- Momentary switch attached from pin 2 to ground
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- Built-in LED on pin 13
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Unlike pinMode(INPUT), there is no pull-down resistor necessary. An internal
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20K-ohm resistor is pulled to 5V. This configuration causes the input to
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read HIGH when the switch is open, and LOW when it is closed.
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created 14 March 2012
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by Scott Fitzgerald
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http://www.arduino.cc/en/Tutorial/InputPullupSerial
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This example code is in the public domain
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*/
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void setup() {
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//start serial connection
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Serial.begin(9600);
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//configure pin 2 as an input and enable the internal pull-up resistor
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pinMode(2, INPUT_PULLUP);
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pinMode(13, OUTPUT);
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}
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void loop() {
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//read the pushbutton value into a variable
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int sensorVal = digitalRead(2);
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//print out the value of the pushbutton
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Serial.println(sensorVal);
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// Keep in mind the pull-up means the pushbutton's
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// logic is inverted. It goes HIGH when it's open,
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// and LOW when it's pressed. Turn on pin 13 when the
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// button's pressed, and off when it's not:
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if (sensorVal == HIGH) {
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digitalWrite(13, LOW);
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} else {
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digitalWrite(13, HIGH);
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}
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}
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