Mbed OS Reference | AnalogIn.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2006-2019 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_ANALOGIN_H
 #define MBED_ANALOGIN_H
 
 #include "platform/platform.h"
 
 #if DEVICE_ANALOGIN || defined(DOXYGEN_ONLY)
 
 #include "hal/analogin_api.h"
 #include "platform/SingletonPtr.h"
 #include "platform/PlatformMutex.h"
 
 #include <cmath>
 
 namespace mbed {
 /** \defgroup mbed-os-public Public API */
 
 /** \defgroup drivers-public-api Drivers
  * \ingroup mbed-os-public
  */
 
 /** \defgroup drivers-public-api-gpio GPIO
  * \ingroup drivers-public-api
  */
 
 /**
  * \defgroup drivers_AnalogIn AnalogIn class
  * \ingroup drivers-public-api-gpio
  * @{
  */
 
 /** An analog input, used for reading the voltage on a pin
  *
  * @note Synchronization level: Thread safe
  *
  * Example:
  * @code
  * // Print messages when the AnalogIn is greater than 50%
  *
  * #include "mbed.h"
  *
  * AnalogIn temperature(p20);
  *
  * int main() {
  *     while(1) {
  *         if(temperature > 0.5) {
  *             printf("Too hot! (%f)", temperature.read());
  *         }
  *     }
  * }
  * @endcode
  */
 class AnalogIn {
 
 public:
 
     /** Create an AnalogIn, connected to the specified pin
      *
      * @param pinmap reference to structure which holds static pinmap.
      * @param vref (optional) Reference voltage of this AnalogIn instance (defaults to target.default-adc-vref).
      *
      * @note An input voltage at or above the given vref value will produce a 1.0 result when `read` is called
      */
     AnalogIn(const PinMap &pinmap, float vref = MBED_CONF_TARGET_DEFAULT_ADC_VREF);
     AnalogIn(const PinMap &&, float vref = MBED_CONF_TARGET_DEFAULT_ADC_VREF) = delete; // prevent passing of temporary objects
 
     /** Create an AnalogIn, connected to the specified pin
      *
      * @param pin AnalogIn pin to connect to
      * @param vref (optional) Reference voltage of this AnalogIn instance (defaults to target.default-adc-vref).
      *
      * @note An input voltage at or above the given vref value will produce a 1.0 result when `read` is called
      */
     AnalogIn(PinName pin, float vref = MBED_CONF_TARGET_DEFAULT_ADC_VREF);
 
     /** Read the input voltage, represented as a float in the range [0.0, 1.0]
      *
      * @returns A floating-point value representing the current input voltage, measured as a percentage
      */
     float read();
 
     /** Read the input voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
      *
      * @returns
      *   16-bit unsigned short representing the current input voltage, normalized to a 16-bit value
      */
     unsigned short read_u16();
 
     /**
      * Read the input voltage in volts. The output depends on the target board's
      * ADC reference voltage (typically equal to supply voltage). The ADC reference voltage
      * sets the maximum voltage the ADC can quantify (ie: ADC output == ADC_MAX_VALUE when Vin == Vref)
      *
      * The target's default ADC reference voltage is determined by the configuration
      * option target.default-adc_vref. The reference voltage for a particular input
      * can be manually specified by either the constructor or `AnalogIn::set_reference_voltage`.
      *
      * @returns A floating-point value representing the current input voltage, measured in volts.
      */
     float read_voltage();
 
     /**
      * Sets this AnalogIn instance's reference voltage.
      *
      * The AnalogIn's reference voltage is used to scale the output when calling AnalogIn::read_volts
      *
      * @param[in] vref New ADC reference voltage for this AnalogIn instance.
      */
     void set_reference_voltage(float vref);
 
     /**
      * Gets this AnalogIn instance's reference voltage.
      *
      * @returns A floating-point value representing this AnalogIn's reference voltage, measured in volts.
      */
     float get_reference_voltage() const;
 
     /** An operator shorthand for read()
      *
      * The float() operator can be used as a shorthand for read() to simplify common code sequences
      *
      * Example:
      * @code
      * float x = volume.read();
      * float x = volume;
      *
      * if(volume.read() > 0.25) { ... }
      * if(volume > 0.25) { ... }
      * @endcode
      */
     operator float()
     {
         // Underlying call is thread safe
         return read();
     }
 
     virtual ~AnalogIn()
     {
         lock();
         analogin_free(&_adc);
         unlock();
     }
 
 protected:
 #if !defined(DOXYGEN_ONLY)
     virtual void lock()
     {
         _mutex->lock();
     }
 
     virtual void unlock()
     {
         _mutex->unlock();
     }
 
     analogin_t _adc;
     static SingletonPtr<PlatformMutex> _mutex;
 
     float _vref;
 
 #endif //!defined(DOXYGEN_ONLY)
 
 };
 
 /** @}*/
 
 } // namespace mbed
 
 #endif
 
 #endif
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