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BusInOut class hierarchy

Use the BusInOut interface as a bidirectional bus that supports up to 16 DigitalInOut pins that you can read and write as one value.

You can create a BusInOut object from any microcontroller pins that are capable of performing digital input and output functions. There is no restriction on the port or bus that the pins are physically connected to.


The order of pins in the constructor is the reverse order of the pins in the byte order. If you have BusInOut(a,b,c,d,e,f,g,h), then the order of bits in the byte is hgfedcba with a being bit 0, b being bit 1, c being bit 2 and so on.

BusInOut class reference

Public Member Functions
 BusInOut (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)
 Create a BusInOut, connected to the specified pins. More...
 BusInOut (PinName pins[16])
 Create a BusInOut, connected to the specified pins. More...
void write (int value)
 Write the value to the output bus. More...
int read ()
 Read the value currently output on the bus. More...
void output ()
 Set all the pins in bus as output. More...
void input ()
 Set all the pins in bus as an input. More...
void mode (PinMode pull)
 Set the input pin mode for all the pins in bus. More...
int mask ()
 Binary mask of bus pins connected to actual pins (not NC pins) If bus pin is in NC state make corresponding bit will be cleared (set to 0), else bit will be set to 1. More...
BusInOutoperator= (int v)
 A shorthand for write() More...
DigitalInOutoperator[] (int index)
 Access to particular bit in random-iterator fashion. More...
 operator int ()
 A shorthand for read() More...

BusInOut hello, world

 * Copyright (c) 2014-2020 Arm Limited and affiliates.
 * SPDX-License-Identifier: Apache-2.0

#include "mbed.h"

BusInOut pins(D0, D1, D2); // Change these pins to buttons on your board.

int main()
    while (1) {
        pins = 0x3;
        if (pins == 0x6) {

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