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mbed-classic/api/PwmOut.h

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/* mbed Microcontroller Library
* Copyright (c) 2006-2013 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef MBED_PWMOUT_H
#define MBED_PWMOUT_H
#include "platform.h"
#if DEVICE_PWMOUT
#include "pwmout_api.h"
namespace mbed {
/** A pulse-width modulation digital output
*
* Example
* @code
* // Fade a led on.
* #include "mbed.h"
*
* PwmOut led(LED1);
*
* int main() {
* while(1) {
* led = led + 0.01;
* wait(0.2);
* if(led == 1.0) {
* led = 0;
* }
* }
* }
* @endcode
*
* @note
* On the LPC1768 and LPC2368, the PWMs all share the same
* period - if you change the period for one, you change it for all.
* Although routines that change the period maintain the duty cycle
* for its PWM, all other PWMs will require their duty cycle to be
* refreshed.
*/
class PwmOut {
public:
/** Create a PwmOut connected to the specified pin
*
* @param pin PwmOut pin to connect to
*/
PwmOut(PinName pin) {
pwmout_init(&_pwm, pin);
}
/** Set the ouput duty-cycle, specified as a percentage (float)
*
* @param value A floating-point value representing the output duty-cycle,
* specified as a percentage. The value should lie between
* 0.0f (representing on 0%) and 1.0f (representing on 100%).
* Values outside this range will be saturated to 0.0f or 1.0f.
*/
void write(float value) {
pwmout_write(&_pwm, value);
}
/** Return the current output duty-cycle setting, measured as a percentage (float)
*
* @returns
* A floating-point value representing the current duty-cycle being output on the pin,
* measured as a percentage. The returned value will lie between
* 0.0f (representing on 0%) and 1.0f (representing on 100%).
*
* @note
* This value may not match exactly the value set by a previous <write>.
*/
float read() {
return pwmout_read(&_pwm);
}
/** Set the PWM period, specified in seconds (float), keeping the duty cycle the same.
*
* @note
* The resolution is currently in microseconds; periods smaller than this
* will be set to zero.
*/
void period(float seconds) {
pwmout_period(&_pwm, seconds);
}
/** Set the PWM period, specified in milli-seconds (int), keeping the duty cycle the same.
*/
void period_ms(int ms) {
pwmout_period_ms(&_pwm, ms);
}
/** Set the PWM period, specified in micro-seconds (int), keeping the duty cycle the same.
*/
void period_us(int us) {
pwmout_period_us(&_pwm, us);
}
/** Set the PWM pulsewidth, specified in seconds (float), keeping the period the same.
*/
void pulsewidth(float seconds) {
pwmout_pulsewidth(&_pwm, seconds);
}
/** Set the PWM pulsewidth, specified in milli-seconds (int), keeping the period the same.
*/
void pulsewidth_ms(int ms) {
pwmout_pulsewidth_ms(&_pwm, ms);
}
/** Set the PWM pulsewidth, specified in micro-seconds (int), keeping the period the same.
*/
void pulsewidth_us(int us) {
pwmout_pulsewidth_us(&_pwm, us);
}
#ifdef MBED_OPERATORS
/** A operator shorthand for write()
*/
PwmOut& operator= (float value) {
write(value);
return *this;
}
PwmOut& operator= (PwmOut& rhs) {
write(rhs.read());
return *this;
}
/** An operator shorthand for read()
*/
operator float() {
return read();
}
#endif
protected:
pwmout_t _pwm;
};
} // namespace mbed
#endif
#endif