gcc4mbed/external/mbed/.svn/text-base/PwmOut.h.svn-base

   1 /* mbed Microcontroller Library - PwmOut
   2  * Copyright (c) 2007-2009 ARM Limited. All rights reserved.
   3  * sford
   4  */
   5
   6 #ifndef MBED_PWMOUT_H
   7 #define MBED_PWMOUT_H
   8
   9 #include "platform.h"
  10 #include "PinNames.h"
  11 #include "PeripheralNames.h"
  12 #include "Base.h"
  13
  14 namespace mbed {
  15
  16 /* Class: PwmOut
  17  *  A pulse-width modulation digital output
  18  *
  19  * Example
  20  * > // Fade a led on.
  21  * > #include "mbed.h"
  22  * >
  23  * > PwmOut led(LED1);
  24  * >
  25  * > int main() {
  26  * >     while(1) {
  27  * >         led = led + 0.01;
  28  * >         wait(0.2);
  29  * >         if(led == 1.0) {
  30  * >             led = 0;
  31  * >         }
  32  * >     }
  33  * > }
  34  *
  35  *  Note that on the LPC1768 and LPC2368, the PWMs all share the same
  36  *  period - if you change the period for one, you change it for all.
  37  *  Although routines that change the period maintain the duty cycle
  38  *  for its PWM, all other PWMs will require their duty cycle to be
  39  *  refreshed.
  40  */
  41 class PwmOut : public Base {
  42
  43 public:
  44
  45     /* Constructor: PwmOut
  46      *  Create a PwmOut connected to the specified pin
  47      *
  48      * Variables:
  49      *  pin - PwmOut pin to connect to
  50      */
  51     PwmOut(PinName pin, const char *name = NULL);
  52
  53     /* Function: write
  54      *  Set the ouput duty-cycle, specified as a percentage (float)
  55      *
  56      * Variables:
  57      *  value - A floating-point value representing the output duty-cycle,
  58      *    specified as a percentage. The value should lie between
  59      *    0.0f (representing on 0%) and 1.0f (representing on 100%).
  60      *    Values outside this range will be saturated to 0.0f or 1.0f.
  61      */
  62     void write(float value);
  63
  64     /* Function: read
  65      *  Return the current output duty-cycle setting, measured as a percentage (float)
  66      *
  67      * Variables:
  68      *  returns - A floating-point value representing the current duty-cycle being output on the pin,
  69      *    measured as a percentage. The returned value will lie between
  70      *    0.0f (representing on 0%) and 1.0f (representing on 100%).
  71      *
  72      * Note:
  73      *  This value may not match exactly the value set by a previous <write>.
  74      */
  75     float read();
  76
  77     /* Function: period
  78      *  Set the PWM period, specified in seconds (float), keeping the
  79      *  duty cycle the same.
  80      *
  81      *  Note:
  82      *   The resolution is currently in microseconds; periods smaller than this
  83      *   will be set to zero.
  84      */
  85     void period(float seconds);
  86
  87     /* Function: period_ms
  88      *  Set the PWM period, specified in milli-seconds (int), keeping the
  89      *  duty cycle the same.
  90      */
  91     void period_ms(int ms);
  92
  93     /* Function: period_us
  94      *  Set the PWM period, specified in micro-seconds (int), keeping the
  95      *  duty cycle the same.
  96      */
  97     void period_us(int us);
  98
  99     /* Function: pulsewidth
 100      *  Set the PWM pulsewidth, specified in seconds (float), keeping the
 101      *  period the same.
 102      */
 103     void pulsewidth(float seconds);
 104
 105     /* Function: pulsewidth_ms
 106      *  Set the PWM pulsewidth, specified in milli-seconds (int), keeping
 107      *  the period the same.
 108      */
 109     void pulsewidth_ms(int ms);
 110
 111     /* Function: pulsewidth_us
 112      *  Set the PWM pulsewidth, specified in micro-seconds (int), keeping
 113      *  the period the same.
 114      */
 115     void pulsewidth_us(int us);
 116
 117 #ifdef MBED_OPERATORS
 118     /* Function: operator=
 119      *  A operator shorthand for <write()>
 120      */
 121     PwmOut& operator= (float value);
 122     PwmOut& operator= (PwmOut& rhs);
 123
 124     /* Function: operator float()
 125      *  An operator shorthand for <read()>
 126      */
 127     operator float();
 128 #endif
 129
 130 #ifdef MBED_RPC
 131     virtual const struct rpc_method *get_rpc_methods();
 132     static struct rpc_class *get_rpc_class();
 133 #endif
 134
 135 protected:
 136
 137     PWMName _pwm;
 138
 139 };
 140
 141 } // namespace mbed
 142
 143 #endif