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 DEVICE_ANALOGIN
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 
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  */
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      * @param name (optional) A string to identify the object
00060      */
00061     AnalogIn(PinName pin) {
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         lock();
00073         float ret = analogin_read(&_adc);
00074         unlock();
00075         return ret;
00076     }
00077 
00078     /** Read the input voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
00079      *
00080      * @returns
00081      *   16-bit unsigned short representing the current input voltage, normalised to a 16-bit value
00082      */
00083     unsigned short read_u16() {
00084         lock();
00085         unsigned short ret = analogin_read_u16(&_adc);
00086         unlock();
00087         return ret;
00088     }
00089 
00090     /** An operator shorthand for read()
00091      *
00092      * The float() operator can be used as a shorthand for read() to simplify common code sequences
00093      *
00094      * Example:
00095      * @code
00096      * float x = volume.read();
00097      * float x = volume;
00098      *
00099      * if(volume.read() > 0.25) { ... }
00100      * if(volume > 0.25) { ... }
00101      * @endcode
00102      */
00103     operator float() {
00104         // Underlying call is thread safe
00105         return read();
00106     }
00107 
00108     virtual ~AnalogIn() {
00109         // Do nothing
00110     }
00111 
00112 protected:
00113 
00114     virtual void lock() {
00115         _mutex->lock();
00116     }
00117 
00118     virtual void unlock() {
00119         _mutex->unlock();
00120     }
00121 
00122     analogin_t _adc;
00123     static SingletonPtr<PlatformMutex>  _mutex;
00124 };
00125 
00126 } // namespace mbed
00127 
00128 #endif
00129 
00130 #endif
00131 
00132 /** @}*/