DigitalIn

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The DigitalIn interface is used to read the value of a digital input pin.

Any of the numbered mbed pins can be used as a DigitalIn.

Hello World!

Flash an LED while a DigitalIn is true

#include "mbed.h"

DigitalIn enable(p5);
DigitalOut led(LED1);

int main() {
    while(1) {
        if(enable) {
            led = !led;
        }
        wait(0.25);
    }
}

API

API summary

DigitalIn	A digital input, used for reading the state of a pin
Functions
DigitalIn	Create a DigitalIn connected to the specified pin
read	Read the input, represented as 0 or 1 (int)
mode	Set the input pin mode
operator int()	An operator shorthand for read()

class DigitalIn : public Base

A digital input, used for reading the state of a pin

DigitalIn( PinName pin,
const char * name = NULL )

Create a DigitalIn connected to the specified pin

int read()

Read the input, represented as 0 or 1 (int)

void mode( PinMode pull )

Set the input pin mode

operator int()

An operator shorthand for read()

Details

The pin input is logic '0' for any voltage on the pin below 0.8v, and '1' for any voltage above 2.0v. By default, the DigitalIn is setup with an internal pull-down resistor.

Examples

Boolean logic - NOT, AND, OR, XOR

#include "mbed.h"

DigitalIn a(p5);
DigitalIn b(p6);
DigitalOut z_not(LED1);
DigitalOut z_and(LED2);
DigitalOut z_or(LED3);
DigitalOut z_xor(LED4);

int main() {
    while(1) {
        z_not = !a;
        z_and = a && b;
        z_or = a || b;
        z_xor = a ^ b;
    }
}

Flash a LED while a pin is true, then exit

#include "mbed.h"

DigitalIn enable(p5);
DigitalOut led(LED1);

int main() {
    while(enable) {
        led = !led;
        wait(0.25);
    }
}