Mbed OS Reference | DigitalIn.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2006-2020 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * 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,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 #ifndef MBED_DIGITALIN_H
 #define MBED_DIGITALIN_H
 
 #include "platform/platform.h"
 
 #include "interfaces/InterfaceDigitalIn.h"
 #include "hal/gpio_api.h"
 
 namespace mbed {
 
 /**
  * \defgroup drivers_DigitalIn DigitalIn class
  * \ingroup drivers-public-api-gpio
  * @{
  */
 
 /** A digital input, used for reading the state of a pin
  *
  * @note Synchronization level: Interrupt safe
  *
  * Example:
  * @code
  * // 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;
  *         }
  *         ThisThread::sleep_for(250);
  *     }
  * }
  * @endcode
  */
 class DigitalIn
 #ifdef FEATURE_EXPERIMENTAL_API
     final : public interface::DigitalIn
 #endif
 {
 
 public:
     /** Create a DigitalIn connected to the specified pin
      *
      *  @param pin DigitalIn pin to connect to
      */
     DigitalIn(PinName pin) : gpio()
     {
         // No lock needed in the constructor
         gpio_init_in(&gpio, pin);
     }
 
     /** Create a DigitalIn connected to the specified pin
      *
      *  @param pin DigitalIn pin to connect to
      *  @param mode the initial mode of the pin
      */
     DigitalIn(PinName pin, PinMode mode) : gpio()
     {
         // No lock needed in the constructor
         gpio_init_in_ex(&gpio, pin, mode);
     }
 
     /** Class destructor, deinitialize the pin
      */
     ~DigitalIn()
     {
         gpio_free(&gpio);
     }
 
     /** Read the input, represented as 0 or 1 (int)
      *
      *  @returns
      *    An integer representing the state of the input pin,
      *    0 for logical 0, 1 for logical 1
      */
     int read()
     {
         // Thread safe / atomic HAL call
         return gpio_read(&gpio);
     }
 
     /** Set the input pin mode
      *
      *  @param pull PullUp, PullDown, PullNone, OpenDrain
      */
     void mode(PinMode pull);
     /** Return the output setting, represented as 0 or 1 (int)
      *
      *  @returns
      *    Non zero value if pin is connected to uc GPIO
      *    0 if gpio object was initialized with NC
      */
     int is_connected()
     {
         // Thread safe / atomic HAL call
         return gpio_is_connected(&gpio);
     }
 
     /** An operator shorthand for read()
      * \sa DigitalIn::read()
      * @code
      *      DigitalIn  button(BUTTON1);
      *      DigitalOut led(LED1);
      *      led = button;   // Equivalent to led.write(button.read())
      * @endcode
      */
     operator int()
     {
         // Underlying read is thread safe
         return read();
     }
 
 protected:
 #if !defined(DOXYGEN_ONLY)
     gpio_t gpio;
 #endif //!defined(DOXYGEN_ONLY)
 };
 
 /** @}*/
 
 } // namespace mbed
 
 #endif
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