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BusOut class hierarchy

Use the BusOut interface to create a number of DigitalOut pins that you can write as one value. This API is useful for writing multiple outputs at once. You can use this API to write clearer code faster.

You can use any of the numbered Arm Mbed pins as a DigitalOut in the BusOut.


  • You can have up to 16 pins in a Bus.
  • The order of pins in the constructor is the reverse order of the pins in the byte order. So if you have BusOut(a,b,c,d,e,f,g,h), then the order of bits in the byte would be hgfedcba with a being bit 0, b being bit 1, c being bit 2 and so on.

BusOut class reference

Public Member Functions
 BusOut (PinName p0, PinName p1=NC, PinName p2=NC, PinName p3=NC, PinName p4=NC, PinName p5=NC, PinName p6=NC, PinName p7=NC, PinName p8=NC, PinName p9=NC, PinName p10=NC, PinName p11=NC, PinName p12=NC, PinName p13=NC, PinName p14=NC, PinName p15=NC)
 BusOut (PinName pins[16])
void write (int value)
int read ()
int mask ()
BusOutoperator= (int v)
BusOutoperator= (BusOut &rhs)
DigitalOutoperator[] (int index)
 operator int ()
Protected Member Functions
virtual void lock ()
virtual void unlock ()
Protected Attributes
DigitalOut_pin [16]
int _nc_mask
PlatformMutex _mutex

BusOut Hello World!

/* mbed Example Program
 * Copyright (c) 2006-2014 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"
BusOut myleds(LED1, LED2, LED3, LED4);
int main() {
    while(1) {
        for(int i=0; i<16; i++) {
            myleds = i;
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