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Use the PortInOut interface to read and write an underlying GPIO port as one value. This is much faster than BusInOut because you can write a port all at once, but it is much less flexible because you are constrained by the port and bit layout of the underlying GPIO ports.

A mask can be supplied so you only use certain parts of a port, allowing other bits to be used for other interfaces.

PortInOut class reference

Public Member Functions
 PortInOut (PortName port, int mask=0xFFFFFFFF)
 Create an PortInOut, connected to the specified port. More...
void write (int value)
 Write the value to the output port. More...
int read ()
 Read the value currently output on the port. More...
void output ()
 Set as an output. More...
void input ()
 Set as an input. More...
void mode (PinMode mode)
 Set the input pin mode. More...
PortInOutoperator= (int value)
 A shorthand for write() More...
PortInOutoperator= (PortInOut &rhs)
 A shorthand for write() More...
 operator int ()
 A shorthand for read() More...

PortInOut 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.

// Toggle all four LEDs
#include "mbed.h"
// LED1 = P1.18  LED2 = P1.20  LED3 = P1.21  LED4 = P1.23
#define LED_MASK 0x00B40000
PortInOut ledport(Port1, LED_MASK);
int main() {
    int v = ledport;
    while(1) {
        ledport = LED_MASK;
        ledport = 0;
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