PwmOut.h

00001 /* mbed Microcontroller Library - PwmOut
00002  * Copyright (c) 2007-2011 ARM Limited. All rights reserved.
00003  */ 
00004  
00005 #ifndef MBED_PWMOUT_H
00006 #define MBED_PWMOUT_H
00007 
00008 #include "device.h"
00009 
00010 #if DEVICE_PWMOUT
00011 
00012 #include "platform.h"
00013 #include "PinNames.h"
00014 #include "PeripheralNames.h"
00015 #include "Base.h"
00016 
00017 namespace mbed {
00018 
00019 /* Class: PwmOut
00020  *  A pulse-width modulation digital output
00021  *
00022  * Example
00023  * > // Fade a led on.
00024  * > #include "mbed.h"
00025  * >
00026  * > PwmOut led(LED1);
00027  * > 
00028  * > int main() {
00029  * >     while(1) {
00030  * >         led = led + 0.01;
00031  * >         wait(0.2);
00032  * >         if(led == 1.0) {
00033  * >             led = 0;
00034  * >         }
00035  * >     }
00036  * > }
00037  *
00038  *  Note that on the LPC1768 and LPC2368, the PWMs all share the same
00039  *  period - if you change the period for one, you change it for all.
00040  *  Although routines that change the period maintain the duty cycle
00041  *  for its PWM, all other PWMs will require their duty cycle to be
00042  *  refreshed.
00043  */
00044 class PwmOut : public Base {
00045 
00046 public:
00047 
00048     /* Constructor: PwmOut
00049      *  Create a PwmOut connected to the specified pin
00050      *
00051      * Variables:
00052      *  pin - PwmOut pin to connect to
00053      */
00054     PwmOut(PinName pin, const char *name = NULL);
00055 
00056     /* Function: write
00057      *  Set the ouput duty-cycle, specified as a percentage (float)
00058      *
00059      * Variables:
00060      *  value - A floating-point value representing the output duty-cycle, 
00061      *    specified as a percentage. The value should lie between
00062      *    0.0f (representing on 0%) and 1.0f (representing on 100%).
00063      *    Values outside this range will be saturated to 0.0f or 1.0f.   
00064      */
00065     void write(float value);
00066 
00067     /* Function: read
00068      *  Return the current output duty-cycle setting, measured as a percentage (float)
00069      *
00070      * Variables:
00071      *  returns - A floating-point value representing the current duty-cycle being output on the pin, 
00072      *    measured as a percentage. The returned value will lie between
00073      *    0.0f (representing on 0%) and 1.0f (representing on 100%).
00074      *
00075      * Note:
00076      *  This value may not match exactly the value set by a previous <write>.
00077      */
00078     float read();
00079     
00080     /* Function: period
00081      *  Set the PWM period, specified in seconds (float), keeping the
00082      *  duty cycle the same.
00083      *
00084      *  Note:
00085      *   The resolution is currently in microseconds; periods smaller than this
00086      *   will be set to zero.
00087      */
00088     void period(float seconds);
00089 
00090     /* Function: period_ms
00091      *  Set the PWM period, specified in milli-seconds (int), keeping the
00092      *  duty cycle the same.
00093      */
00094     void period_ms(int ms);
00095 
00096     /* Function: period_us
00097      *  Set the PWM period, specified in micro-seconds (int), keeping the
00098      *  duty cycle the same.
00099      */
00100     void period_us(int us);
00101 
00102     /* Function: pulsewidth
00103      *  Set the PWM pulsewidth, specified in seconds (float), keeping the
00104      *  period the same.
00105      */
00106     void pulsewidth(float seconds);
00107 
00108     /* Function: pulsewidth_ms
00109      *  Set the PWM pulsewidth, specified in milli-seconds (int), keeping
00110      *  the period the same.
00111      */
00112     void pulsewidth_ms(int ms);
00113 
00114     /* Function: pulsewidth_us
00115      *  Set the PWM pulsewidth, specified in micro-seconds (int), keeping
00116      *  the period the same.
00117      */
00118     void pulsewidth_us(int us);
00119 
00120 #ifdef MBED_OPERATORS
00121     /* Function: operator=
00122      *  A operator shorthand for <write()>
00123      */
00124     PwmOut& operator= (float value);
00125     PwmOut& operator= (PwmOut& rhs);
00126 
00127     /* Function: operator float()
00128      *  An operator shorthand for <read()>
00129      */
00130     operator float();
00131 #endif
00132 
00133 #ifdef MBED_RPC
00134     virtual const struct rpc_method *get_rpc_methods();
00135     static struct rpc_class *get_rpc_class();
00136 #endif
00137 
00138 protected:
00139 
00140     PWMName _pwm;
00141 
00142 };
00143 
00144 } // namespace mbed
00145 
00146 #endif
00147 
00148 #endif