An interface to read a PWM input signal, using InterruptIn

Dependents:   PwmIn_HelloWorld PwmIn_ModSerial CHR6dm_reading tugboat ... more

Files at this revision

API Documentation at this revision

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

PwmIn.cpp Show annotated file Show diff for this revision Revisions of this file
PwmIn.h Show annotated file Show diff for this revision Revisions of this file
main.cpp Show diff for this revision Revisions of this file
mbed.bld Show diff for this revision Revisions of this file
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