DebounceIn.h

00001 /* A digital input with switch debouncing
00002  * Copyright 2015, Takuo Watanabe
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 
00017 #ifndef DEBOUNCEIN_H_
00018 #define DEBOUNCEIN_H_
00019 
00020 #include "mbed.h"
00021 
00022 /** A digital input with switch debouncing
00023  *
00024  * Example:
00025  * @code
00026  * #include "mbed.h"
00027  * #include "DebounceIn.h"
00028  *
00029  * int nrise = 0, nfall = 0;
00030  * void rise() { nrise++; }
00031  * void fall() { nfall++; }
00032  *
00033  * int main() {
00034  *     DebounceIn button(p14);
00035  *     button.rise(rise);
00036  *     button.fall(fall);
00037  *     while (true) {
00038  *         printf("nrise=%d, nfall=%d\n", nrise, nfall);
00039  *         wait(1);
00040  *     }
00041  * }
00042  * @endcode
00043  */
00044 class DebounceIn: public mbed::DigitalIn {
00045 public:
00046     /** Create a DebounceIn object connected to the specified pin
00047      *
00048      * @param pin  DebounceIn pin to connect to
00049      * @param us   Input sampling rate (default 1000 microseconds)
00050      */
00051     DebounceIn(PinName pin, timestamp_t us = 1000);
00052 
00053     virtual ~DebounceIn();
00054 
00055     /** Set the input sampling rate
00056      *
00057      * @param us  Input sampling rate
00058      */
00059     void set_sample_rate(timestamp_t us);
00060 
00061     /** Read the input, represented as 0 or 1 (int)
00062      *
00063      * @returns  An integer representing the state of the input pin
00064      */
00065     int read(void);
00066 
00067 #ifdef MBED_OPERATORS
00068     /** An operator shorthand for read()
00069      */
00070     operator int();
00071 #endif
00072 
00073     /** Attach a function to call when a rising edge occurs on the input
00074      *
00075      * @param fptr pointer to a void function, or 0 to set as none
00076      */
00077     void rise(void (*fptr)(void));
00078 
00079     /** Attach a member function to call when a rising edge occurs on the input
00080      *
00081      *  @param tptr pointer to the object to call the member function on
00082      *  @param mptr pointer to the member function to be called
00083      */
00084     template<typename T>
00085     void rise(T* tptr, void (T::*mptr)(void)) {
00086         _rise.attach(tptr, mptr);
00087     }
00088 
00089     /** Attach a function to call when a falling edge occurs on the input
00090      *
00091      *  @param fptr pointer to a void function, or 0 to set as none
00092      */
00093     void fall(void (*fptr)(void));
00094 
00095     /** Attach a member function to call when a falling edge occurs on the input
00096      *
00097      *  @param tptr pointer to the object to call the member function on
00098      *  @param mptr pointer to the member function to be called
00099      */
00100     template<typename T>
00101     void fall(T* tptr, void (T::*mptr)(void)) {
00102         _fall.attach(tptr, mptr);
00103     }
00104 
00105 private:
00106     Ticker _ticker;
00107     int _prev, _curr;
00108     FunctionPointer _rise, _fall;
00109     void sample(void);
00110 };
00111 
00112 #endif /* DEBOUNCEIN_H_ */