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105 lines
3.2 KiB
105 lines
3.2 KiB
#include "mbed.h"
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#ifndef MICROBIT_DYNAMIC_PWM_H
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#define MICROBIT_DYNAMIC_PWM_H
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#define NO_PWMS 3
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#define MICROBIT_DISPLAY_PWM_PERIOD 1000
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enum PwmPersistence
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{
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PWM_PERSISTENCE_TRANSIENT = 1,
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PWM_PERSISTENCE_PERSISTENT = 2,
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};
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/**
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* Class definition for DynamicPwm.
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*
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* This class addresses a few issues found in the underlying libraries.
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* This provides the ability for a neat, clean swap between PWM channels.
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*/
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class DynamicPwm : public PwmOut
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{
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private:
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static DynamicPwm* pwms[NO_PWMS];
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static uint8_t lastUsed;
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uint8_t flags;
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/**
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* An internal constructor used when allocating a new DynamicPwm representation
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* @param pin the name of the pin for the pwm to target
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* @param persistance the level of persistence for this pin PWM_PERSISTENCE_PERSISTENT (can not be replaced until freed, should only be used for system services really.)
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* or PWM_PERSISTENCE_TRANSIENT (can be replaced at any point if a channel is required.)
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* @param period the frequency of the pwm channel in us.
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*/
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DynamicPwm(PinName pin, PwmPersistence persistence = PWM_PERSISTENCE_TRANSIENT, int period = MICROBIT_DISPLAY_PWM_PERIOD);
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public:
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/**
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* Redirects the pwm channel to point at a different pin.
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* @param pin the new pin to direct PWM at.
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*
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* Example:
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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* pwm->redirect(PinName n2); // pwm is now produced on n2
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* @endcode
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*/
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void redirect(PinName pin);
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/**
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* Retrieves a pointer to the first available free pwm channel - or the first one that can be reallocated.
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* @param pin the name of the pin for the pwm to target
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* @param persistance the level of persistence for this pin PWM_PERSISTENCE_PERSISTENT (can not be replaced until freed, should only be used for system services really.)
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* or PWM_PERSISTENCE_TRANSIENT (can be replaced at any point if a channel is required.)
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* @param period the frequency of the pwm channel in us.
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*
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* Example:
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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* @endcode
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*/
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static DynamicPwm* allocate(PinName pin, PwmPersistence persistence = PWM_PERSISTENCE_TRANSIENT, int period = MICROBIT_DISPLAY_PWM_PERIOD);
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/**
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* Frees this DynamicPwm instance if the pointer is valid.
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*
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* Example:
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate();
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* pwm->release();
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* @endcode
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*/
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void release();
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/**
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* Retreives the pin name associated with this DynamicPwm instance.
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*
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* Example:
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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* pwm->getPinName(); // equal to n
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* @endcode
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*/
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PinName getPinName();
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/**
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* Sets the period used by the WHOLE PWM module. Any changes to the period will AFFECT ALL CHANNELS.
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*
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* Example:
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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* pwm->setPeriodUs(1000); // period now is 1ms
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* @endcode
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*
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* @note The display uses the pwm module, if you change this value the display may flicker.
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*/
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void setPeriodUs(int period);
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};
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#endif
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