Mistake on this page?
Report an issue in GitHub or email us


Use the AnalogOut interface to set the output voltage of an analog output pin specified as a percentage or as an unsigned short. Mbed OS provides separate APIs to use percentage or range. Mbed OS supports a maximum resolution VCC/65,536 V, though the actual resolution depends on the hardware.

Note: Not all pins are capable of being AnalogOut, so check the pinmap for your board.

AnalogOut class reference

Public Member Functions
 AnalogOut (PinName pin)
 Create an AnalogOut connected to the specified pin. More...
 AnalogOut (const PinMap &&)=delete
 Create an AnalogOut connected to the specified pin. More...
void write (float value)
 Set the output voltage, specified as a percentage (float) More...
void write_u16 (unsigned short value)
 Set the output voltage, represented as an unsigned short in the range [0x0, 0xFFFF]. More...
float read ()
 Return the current output voltage setting, measured as a percentage (float) More...
AnalogOutoperator= (float percent)
 An operator shorthand for write() More...
AnalogOutoperator= (AnalogOut &rhs)
 An operator shorthand for write() More...
 operator float ()
 An operator shorthand for read() More...
virtual ~AnalogOut ()

AnalogOut hello, world

/* mbed Example Program
 * Copyright (c) 2006-2015 ARM Limited
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

#include "mbed.h"

// Initialize a pins to perform analog and digital output fucntions
AnalogOut  aout(A5);
DigitalOut dout(LED1);

int main(void)
    while (1) {
        // change the voltage on the digital output pin by 0.1 * VCC
        //  and print what the measured voltage should be (assuming VCC = 3.3v)
        for (float i = 0.0f; i < 1.0f; i += 0.1f) {
            aout = i;
            printf("aout = %1.2f volts\n", aout.read() * 3.3f);
            // turn on the led if the voltage is greater than 0.5f * VCC
            dout = (aout > 0.5f) ? 1 : 0;

AnalogOut example

Create a sine wave.

#include "mbed.h"

const double pi = 3.141592653589793238462;
const double amplitude = 0.5f;
const double offset = 65535/2;

// The sinewave is created on this pin
AnalogOut aout(A5);

int main()
    double rads = 0.0;
    uint16_t sample = 0;
    while(1) {
        // sinewave output
        for (int i = 0; i < 360; i++) {
            rads = (pi * i) / 180.0f;
            sample = (uint16_t)(amplitude * (offset * (cos(rads + pi))) + offset);

Important Information for this Arm website

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies. If you are not happy with the use of these cookies, please review our Cookie Policy to learn how they can be disabled. By disabling cookies, some features of the site will not work.