PwmIn.h

00001 /* mbed PwmIn Library
00002  * Copyright (c) 2008-2010, sford
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022 
00023 #ifndef MBED_PWMIN_H
00024 #define MBED_PWMIN_H
00025 
00026 #include "mbed.h"
00027 
00028 /** PwmIn class to read PWM inputs
00029  * 
00030  * Uses InterruptIn to measure the changes on the input
00031  * and record the time they occur
00032  *
00033  * @note uses InterruptIn, so not available on p19/p20
00034  */
00035 class DummyCT;
00036 
00037 class PwmIn {
00038 public:
00039     /** Create a PwmIn
00040      *
00041      * @param p The pwm input pin (must support InterruptIn)
00042      */ 
00043     PwmIn(PinName p);
00044     
00045     /** Read the current period
00046      *
00047      * @returns the period in micro seconds
00048      */
00049     float period();
00050     
00051     /** Read the current pulsewidth
00052      *
00053      * @returns the pulsewidth in micro seconds
00054      */
00055     float pulsewidth();
00056     
00057     /** Read the current dutycycle
00058      *
00059      * @returns the dutycycle as a percentage, represented between 0.0-1.0
00060      */
00061     float dutycycle();
00062     
00063     /** A assigns a callback function when a new reading is available **/
00064     void (*callbackfunc)(float pulsewidth);
00065     DummyCT* callbackobj;
00066     void (DummyCT::*mcallbackfunc)(float pulsewidth);    
00067   
00068 
00069 protected:        
00070     void rise();
00071     void fall();
00072     
00073     InterruptIn _p;
00074     Timer _t;
00075     float _pulsewidth, _period;
00076 };
00077 
00078 #endif