tmk_core/tool/mbed/mbed-sdk/libraries/mbed/api/PwmOut.h

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #ifndef MBED_PWMOUT_H
  17 #define MBED_PWMOUT_H
  18
  19 #include "platform.h"
  20
  21 #if DEVICE_PWMOUT
  22 #include "pwmout_api.h"
  23
  24 namespace mbed {
  25
  26 /** A pulse-width modulation digital output
  27  *
  28  * Example
  29  * @code
  30  * // Fade a led on.
  31  * #include "mbed.h"
  32  *
  33  * PwmOut led(LED1);
  34  *
  35  * int main() {
  36  *     while(1) {
  37  *         led = led + 0.01;
  38  *         wait(0.2);
  39  *         if(led == 1.0) {
  40  *             led = 0;
  41  *         }
  42  *     }
  43  * }
  44  * @endcode
  45  *
  46  * @note
  47  *  On the LPC1768 and LPC2368, the PWMs all share the same
  48  *  period - if you change the period for one, you change it for all.
  49  *  Although routines that change the period maintain the duty cycle
  50  *  for its PWM, all other PWMs will require their duty cycle to be
  51  *  refreshed.
  52  */
  53 class PwmOut {
  54
  55 public:
  56
  57     /** Create a PwmOut connected to the specified pin
  58      *
  59      *  @param pin PwmOut pin to connect to
  60      */
  61     PwmOut(PinName pin) {
  62         pwmout_init(&_pwm, pin);
  63     }
  64
  65     /** Set the ouput duty-cycle, specified as a percentage (float)
  66      *
  67      *  @param value A floating-point value representing the output duty-cycle,
  68      *    specified as a percentage. The value should lie between
  69      *    0.0f (representing on 0%) and 1.0f (representing on 100%).
  70      *    Values outside this range will be saturated to 0.0f or 1.0f.
  71      */
  72     void write(float value) {
  73         pwmout_write(&_pwm, value);
  74     }
  75
  76     /** Return the current output duty-cycle setting, measured as a percentage (float)
  77      *
  78      *  @returns
  79      *    A floating-point value representing the current duty-cycle being output on the pin,
  80      *    measured as a percentage. The returned value will lie between
  81      *    0.0f (representing on 0%) and 1.0f (representing on 100%).
  82      *
  83      *  @note
  84      *  This value may not match exactly the value set by a previous <write>.
  85      */
  86     float read() {
  87         return pwmout_read(&_pwm);
  88     }
  89
  90     /** Set the PWM period, specified in seconds (float), keeping the duty cycle the same.
  91      *
  92      *  @note
  93      *   The resolution is currently in microseconds; periods smaller than this
  94      *   will be set to zero.
  95      */
  96     void period(float seconds) {
  97         pwmout_period(&_pwm, seconds);
  98     }
  99
 100     /** Set the PWM period, specified in milli-seconds (int), keeping the duty cycle the same.
 101      */
 102     void period_ms(int ms) {
 103         pwmout_period_ms(&_pwm, ms);
 104     }
 105
 106     /** Set the PWM period, specified in micro-seconds (int), keeping the duty cycle the same.
 107      */
 108     void period_us(int us) {
 109         pwmout_period_us(&_pwm, us);
 110     }
 111
 112     /** Set the PWM pulsewidth, specified in seconds (float), keeping the period the same.
 113      */
 114     void pulsewidth(float seconds) {
 115         pwmout_pulsewidth(&_pwm, seconds);
 116     }
 117
 118     /** Set the PWM pulsewidth, specified in milli-seconds (int), keeping the period the same.
 119      */
 120     void pulsewidth_ms(int ms) {
 121         pwmout_pulsewidth_ms(&_pwm, ms);
 122     }
 123
 124     /** Set the PWM pulsewidth, specified in micro-seconds (int), keeping the period the same.
 125      */
 126     void pulsewidth_us(int us) {
 127         pwmout_pulsewidth_us(&_pwm, us);
 128     }
 129
 130 #ifdef MBED_OPERATORS
 131     /** A operator shorthand for write()
 132      */
 133     PwmOut& operator= (float value) {
 134         write(value);
 135         return *this;
 136     }
 137
 138     PwmOut& operator= (PwmOut& rhs) {
 139         write(rhs.read());
 140         return *this;
 141     }
 142
 143     /** An operator shorthand for read()
 144      */
 145     operator float() {
 146         return read();
 147     }
 148 #endif
 149
 150 protected:
 151     pwmout_t _pwm;
 152 };
 153
 154 } // namespace mbed
 155
 156 #endif
 157
 158 #endif