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         lock();
00062         analogin_init(&_adc, pin);
00063         unlock();
00064     }
00065 
00066     /** Read the input voltage, represented as a float in the range [0.0, 1.0]
00067      *
00068      * @returns A floating-point value representing the current input voltage, measured as a percentage
00069      */
00070     float read() {
00071         lock();
00072         float ret = analogin_read(&_adc);
00073         unlock();
00074         return ret;
00075     }
00076 
00077     /** Read the input voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
00078      *
00079      * @returns
00080      *   16-bit unsigned short representing the current input voltage, normalised to a 16-bit value
00081      */
00082     unsigned short read_u16() {
00083         lock();
00084         unsigned short ret = analogin_read_u16(&_adc);
00085         unlock();
00086         return ret;
00087     }
00088 
00089     /** An operator shorthand for read()
00090      *
00091      * The float() operator can be used as a shorthand for read() to simplify common code sequences
00092      *
00093      * Example:
00094      * @code
00095      * float x = volume.read();
00096      * float x = volume;
00097      *
00098      * if(volume.read() > 0.25) { ... }
00099      * if(volume > 0.25) { ... }
00100      * @endcode
00101      */
00102     operator float() {
00103         // Underlying call is thread safe
00104         return read();
00105     }
00106 
00107     virtual ~AnalogIn() {
00108         // Do nothing
00109     }
00110 
00111 protected:
00112 
00113     virtual void lock() {
00114         _mutex->lock();
00115     }
00116 
00117     virtual void unlock() {
00118         _mutex->unlock();
00119     }
00120 
00121     analogin_t _adc;
00122     static SingletonPtr<PlatformMutex>  _mutex;
00123 };
00124 
00125 } // namespace mbed
00126 
00127 #endif
00128 
00129 #endif
00130