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 PwmIn {
00036 public:
00037     /** Create a PwmIn
00038      *
00039      * @param p The pwm input pin (must support InterruptIn)
00040      */ 
00041     PwmIn(PinName p);
00042     
00043     /** Read the current period
00044      *
00045      * @returns the period in seconds
00046      */
00047     float period();
00048     
00049     /** Read the current pulsewidth
00050      *
00051      * @returns the pulsewidth in seconds
00052      */
00053     float pulsewidth();
00054     
00055     /** Read the current dutycycle
00056      *
00057      * @returns the dutycycle as a percentage, represented between 0.0-1.0
00058      */
00059     float dutycycle();
00060 
00061 protected:        
00062     void rise();
00063     void fall();
00064     
00065     InterruptIn _p;
00066     Timer _t;
00067     float _pulsewidth, _period;
00068 };
00069 
00070 #endif