AnalogIn.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  * SPDX-License-Identifier: Apache-2.0
00004  *
00005  * Licensed under the Apache License, Version 2.0 (the "License");
00006  * you may not use this file except in compliance with the License.
00007  * You may obtain a copy of the License at
00008  *
00009  *     http://www.apache.org/licenses/LICENSE-2.0
00010  *
00011  * Unless required by applicable law or agreed to in writing, software
00012  * distributed under the License is distributed on an "AS IS" BASIS,
00013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  * See the License for the specific language governing permissions and
00015  * limitations under the License.
00016  */
00017 #ifndef MBED_ANALOGIN_H
00018 #define MBED_ANALOGIN_H
00019 
00020 #include "platform/platform.h"
00021 
00022 #if DEVICE_ANALOGIN || defined(DOXYGEN_ONLY)
00023 
00024 #include "hal/analogin_api.h"
00025 #include "platform/SingletonPtr.h"
00026 #include "platform/PlatformMutex.h"
00027 
00028 namespace mbed {
00029 /** \addtogroup drivers */
00030 
00031 /** An analog input, used for reading the voltage on a pin
00032  *
00033  * @note Synchronization level: Thread safe
00034  *
00035  * Example:
00036  * @code
00037  * // Print messages when the AnalogIn is greater than 50%
00038  *
00039  * #include "mbed.h"
00040  *
00041  * AnalogIn temperature(p20);
00042  *
00043  * int main() {
00044  *     while(1) {
00045  *         if(temperature > 0.5) {
00046  *             printf("Too hot! (%f)", temperature.read());
00047  *         }
00048  *     }
00049  * }
00050  * @endcode
00051  * @ingroup drivers
00052  */
00053 class AnalogIn {
00054 
00055 public:
00056 
00057     /** Create an AnalogIn, connected to the specified pin
00058      *
00059      * @param pin AnalogIn pin to connect to
00060      */
00061     AnalogIn(PinName pin)
00062     {
00063         lock();
00064         analogin_init(&_adc, pin);
00065         unlock();
00066     }
00067 
00068     /** Read the input voltage, represented as a float in the range [0.0, 1.0]
00069      *
00070      * @returns A floating-point value representing the current input voltage, measured as a percentage
00071      */
00072     float read()
00073     {
00074         lock();
00075         float ret = analogin_read(&_adc);
00076         unlock();
00077         return ret;
00078     }
00079 
00080     /** Read the input voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
00081      *
00082      * @returns
00083      *   16-bit unsigned short representing the current input voltage, normalized to a 16-bit value
00084      */
00085     unsigned short read_u16()
00086     {
00087         lock();
00088         unsigned short ret = analogin_read_u16(&_adc);
00089         unlock();
00090         return ret;
00091     }
00092 
00093     /** An operator shorthand for read()
00094      *
00095      * The float() operator can be used as a shorthand for read() to simplify common code sequences
00096      *
00097      * Example:
00098      * @code
00099      * float x = volume.read();
00100      * float x = volume;
00101      *
00102      * if(volume.read() > 0.25) { ... }
00103      * if(volume > 0.25) { ... }
00104      * @endcode
00105      */
00106     operator float()
00107     {
00108         // Underlying call is thread safe
00109         return read();
00110     }
00111 
00112     virtual ~AnalogIn()
00113     {
00114         // Do nothing
00115     }
00116 
00117 protected:
00118 #if !defined(DOXYGEN_ONLY)
00119     virtual void lock()
00120     {
00121         _mutex->lock();
00122     }
00123 
00124     virtual void unlock()
00125     {
00126         _mutex->unlock();
00127     }
00128 
00129     analogin_t _adc;
00130     static SingletonPtr<PlatformMutex>  _mutex;
00131 #endif //!defined(DOXYGEN_ONLY)
00132 };
00133 
00134 } // namespace mbed
00135 
00136 #endif
00137 
00138 #endif
00139