An interface to read a PWM input signal, using InterruptIn
Dependents: PwmIn_HelloWorld PwmIn_ModSerial CHR6dm_reading tugboat ... more
Revision 1:6d68eb9b6bbb, committed 2010-09-02
- Comitter:
- simon
- Date:
- Thu Sep 02 18:17:35 2010 +0000
- Parent:
- 0:2d3d93d7b204
- Commit message:
- Convert previous example in to a library, including doxygen docs
Changed in this revision
diff -r 2d3d93d7b204 -r 6d68eb9b6bbb PwmIn.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/PwmIn.cpp Thu Sep 02 18:17:35 2010 +0000 @@ -0,0 +1,52 @@ +/* mbed PwmIn Library + * Copyright (c) 2008-2010, sford + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "PwmIn.h" + +PwmIn::PwmIn(PinName p) : _p(p) { + _p.rise(this, &PwmIn::rise); + _p.fall(this, &PwmIn::fall); + _period = 0.0; + _pulsewidth = 0.0; + _t.start(); +} + +float PwmIn::period() { + return _period; +} + +float PwmIn::pulsewidth() { + return _pulsewidth; +} + +float PwmIn::dutycycle() { + return _pulsewidth / _period; +} + +void PwmIn::rise() { + _period = _t.read(); + _t.reset(); +} + +void PwmIn::fall() { + _pulsewidth = _t.read(); +}
diff -r 2d3d93d7b204 -r 6d68eb9b6bbb PwmIn.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/PwmIn.h Thu Sep 02 18:17:35 2010 +0000 @@ -0,0 +1,70 @@ +/* mbed PwmIn Library + * Copyright (c) 2008-2010, sford + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#ifndef MBED_PWMIN_H +#define MBED_PWMIN_H + +#include "mbed.h" + +/** PwmIn class to read PWM inputs + * + * Uses InterruptIn to measure the changes on the input + * and record the time they occur + * + * @note uses InterruptIn, so not available on p19/p20 + */ +class PwmIn { +public: + /** Create a PwmIn + * + * @param p The pwm input pin (must support InterruptIn) + */ + PwmIn(PinName p); + + /** Read the current period + * + * @returns the period in seconds + */ + float period(); + + /** Read the current pulsewidth + * + * @returns the pulsewidth in seconds + */ + float pulsewidth(); + + /** Read the current dutycycle + * + * @returns the dutycycle as a percentage, represented between 0.0-1.0 + */ + float dutycycle(); + +protected: + void rise(); + void fall(); + + InterruptIn _p; + Timer _t; + float _pulsewidth, _period; +}; + +#endif
diff -r 2d3d93d7b204 -r 6d68eb9b6bbb main.cpp --- a/main.cpp Wed Feb 17 18:32:34 2010 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,49 +0,0 @@ -// Example PwmIn class to detect PWM inputs, sford -// - Note: uses InterruptIn, so not available on p19/p20 - -#include "mbed.h" - -class PwmIn { -public: - PwmIn(PinName p) : _p(p) { - _p.rise(this, &PwmIn::rise); - _p.fall(this, &PwmIn::fall); - _period = 0.0; - _pulsewidth = 0.0; - _t.start(); - } - - void rise() { - _period = _t.read(); - _t.reset(); - } - - void fall() { - _pulsewidth = _t.read(); - } - - float period() { return _period; } - float pulsewidth() { return _pulsewidth; } - float dutycycle() { return _pulsewidth / _period; } - -protected: - InterruptIn _p; - Timer _t; - float _pulsewidth, _period; -}; - -PwmOut x(p21); -PwmOut y(p22); - -PwmIn a(p5); -PwmIn b(p6); - -int main() { - x = 0.5; - y = 0.2; - while(1) { - printf("a: pw = %f, period = %f\n", a.pulsewidth(), a.period()); - printf("b: pw = %f, period = %f\n", b.pulsewidth(), b.period()); - wait(2); - } -}
diff -r 2d3d93d7b204 -r 6d68eb9b6bbb mbed.bld --- a/mbed.bld Wed Feb 17 18:32:34 2010 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,1 +0,0 @@ -http://mbed.org/users/mbed_official/code/mbed/builds/49a220cc26e0