AnalogIn.h

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