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PwmOut.h
00001 /* mbed Microcontroller Library 00002 * Copyright (c) 2006-2013 ARM Limited 00003 * 00004 * Licensed under the Apache License, Version 2.0 (the "License"); 00005 * you may not use this file except in compliance with the License. 00006 * You may obtain a copy of the License at 00007 * 00008 * http://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 #ifndef MBED_PWMOUT_H 00017 #define MBED_PWMOUT_H 00018 00019 #include "platform.h" 00020 00021 #if DEVICE_PWMOUT 00022 #include "pwmout_api.h" 00023 00024 namespace mbed { 00025 00026 /** A pulse-width modulation digital output 00027 * 00028 * Example 00029 * @code 00030 * // Fade a led on. 00031 * #include "mbed.h" 00032 * 00033 * PwmOut led(LED1); 00034 * 00035 * int main() { 00036 * while(1) { 00037 * led = led + 0.01; 00038 * wait(0.2); 00039 * if(led == 1.0) { 00040 * led = 0; 00041 * } 00042 * } 00043 * } 00044 * @endcode 00045 * 00046 * @note 00047 * On the LPC1768 and LPC2368, the PWMs all share the same 00048 * period - if you change the period for one, you change it for all. 00049 * Although routines that change the period maintain the duty cycle 00050 * for its PWM, all other PWMs will require their duty cycle to be 00051 * refreshed. 00052 */ 00053 class PwmOut { 00054 00055 public: 00056 00057 /** Create a PwmOut connected to the specified pin 00058 * 00059 * @param pin PwmOut pin to connect to 00060 */ 00061 PwmOut(PinName pin) { 00062 pwmout_init(&_pwm, pin); 00063 } 00064 00065 /** Set the ouput duty-cycle, specified as a percentage (float) 00066 * 00067 * @param value A floating-point value representing the output duty-cycle, 00068 * specified as a percentage. The value should lie between 00069 * 0.0f (representing on 0%) and 1.0f (representing on 100%). 00070 * Values outside this range will be saturated to 0.0f or 1.0f. 00071 */ 00072 void write(float value) { 00073 pwmout_write(&_pwm, value); 00074 } 00075 00076 /** Return the current output duty-cycle setting, measured as a percentage (float) 00077 * 00078 * @returns 00079 * A floating-point value representing the current duty-cycle being output on the pin, 00080 * measured as a percentage. The returned value will lie between 00081 * 0.0f (representing on 0%) and 1.0f (representing on 100%). 00082 * 00083 * @note 00084 * This value may not match exactly the value set by a previous <write>. 00085 */ 00086 float read() { 00087 return pwmout_read(&_pwm); 00088 } 00089 00090 /** Set the PWM period, specified in seconds (float), keeping the duty cycle the same. 00091 * 00092 * @note 00093 * The resolution is currently in microseconds; periods smaller than this 00094 * will be set to zero. 00095 */ 00096 void period(float seconds) { 00097 pwmout_period(&_pwm, seconds); 00098 } 00099 00100 /** Set the PWM period, specified in milli-seconds (int), keeping the duty cycle the same. 00101 */ 00102 void period_ms(int ms) { 00103 pwmout_period_ms(&_pwm, ms); 00104 } 00105 00106 /** Set the PWM period, specified in micro-seconds (int), keeping the duty cycle the same. 00107 */ 00108 void period_us(int us) { 00109 pwmout_period_us(&_pwm, us); 00110 } 00111 00112 /** Set the PWM pulsewidth, specified in seconds (float), keeping the period the same. 00113 */ 00114 void pulsewidth(float seconds) { 00115 pwmout_pulsewidth(&_pwm, seconds); 00116 } 00117 00118 /** Set the PWM pulsewidth, specified in milli-seconds (int), keeping the period the same. 00119 */ 00120 void pulsewidth_ms(int ms) { 00121 pwmout_pulsewidth_ms(&_pwm, ms); 00122 } 00123 00124 /** Set the PWM pulsewidth, specified in micro-seconds (int), keeping the period the same. 00125 */ 00126 void pulsewidth_us(int us) { 00127 pwmout_pulsewidth_us(&_pwm, us); 00128 } 00129 00130 #ifdef MBED_OPERATORS 00131 /** A operator shorthand for write() 00132 */ 00133 PwmOut& operator= (float value) { 00134 write(value); 00135 return *this; 00136 } 00137 00138 PwmOut& operator= (PwmOut& rhs) { 00139 write(rhs.read()); 00140 return *this; 00141 } 00142 00143 /** An operator shorthand for read() 00144 */ 00145 operator float() { 00146 return read(); 00147 } 00148 #endif 00149 00150 protected: 00151 pwmout_t _pwm; 00152 }; 00153 00154 } // namespace mbed 00155 00156 #endif 00157 00158 #endif
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