microbit-dal/inc/DynamicPwm.h

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#include "mbed.h"
#ifndef MICROBIT_DYNAMIC_PWM_H
#define MICROBIT_DYNAMIC_PWM_H
#define NO_PWMS 3
enum PwmPersistence
{
PWM_PERSISTENCE_TRANSIENT = 1,
PWM_PERSISTENCE_PERSISTENT = 2,
};
/**
* Class definition for DynamicPwm.
*
* This class addresses a few issues found in the underlying libraries.
* This provides the ability for a neat, clean swap between PWM channels.
*/
class DynamicPwm : public PwmOut
{
private:
static DynamicPwm* pwms[NO_PWMS];
static uint8_t lastUsed;
uint8_t flags;
/**
* An internal constructor used when allocating a new DynamicPwm representation
* @param pin the name of the pin for the pwm to target
* @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.)
* or PWM_PERSISTENCE_TRANSIENT (can be replaced at any point if a channel is required.)
*/
DynamicPwm(PinName pin, PwmPersistence persistence = PWM_PERSISTENCE_TRANSIENT);
public:
/**
* Redirects the pwm channel to point at a different pin.
* @param pin the new pin to direct PWM at.
*
* Example:
* @code
* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
* pwm->redirect(PinName n2); // pwm is now produced on n2
* @endcode
*/
void redirect(PinName pin);
/**
* Retrieves a pointer to the first available free pwm channel - or the first one that can be reallocated.
* @param pin the name of the pin for the pwm to target
* @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.)
* or PWM_PERSISTENCE_TRANSIENT (can be replaced at any point if a channel is required.)
* @param period the frequency of the pwm channel in us.
*
* Example:
* @code
* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
* @endcode
*/
static DynamicPwm* allocate(PinName pin, PwmPersistence persistence = PWM_PERSISTENCE_TRANSIENT);
/**
* Frees this DynamicPwm instance if the pointer is valid.
*
* Example:
* @code
* DynamicPwm* pwm = DynamicPwm::allocate();
microbit: Memory Optimisation Mega Update This release contains a widespread set of updates and optimisations to the micro:bit runtime, with a view to reducing the SRAM footprint of the whole system. This is to provide as much usable HEAP storage for application programs as possible. Specific updates and optimisations include: - Additional compilation flags to allow the core micro:bit runtime to be configured. These are defined in MicroBitConfig.h - A custom heap allocator. This is now included for two reasons: 1) To provide a simple mechanism to to utilise both the mbed heap space and other memory regions (such as unused memory in the SoftDevice region) as a single virtual heap. 2) To address some issues that have been noted that are attributable to heap fragmentation. The micro:bit heap allocator has a simple algorithm, but one that is chosen to respond well to the relativelt high 'heap churn' found in the micro:bit environment. All micro:bit components and user programs now use this heap allocator trasparently. - Updates to BLE services to remove persistent references to their GATT services. This consumes vast amounts SRAM, rather unecessarily. Instead only handles to the relevant GATT characteristics are now stored. This specifically includes: + MicroBitDFUService + MicroBitEventService + DeviceInformationService - Updates to the Fiber scheduler to save SRAM. More specifically: + Removed the need to hold an empty processor context to intialise fibers. + The IDLE fiber now runs without a stack + fiber stacks are now only created when a fiber is descheduled for the first time, thereby reducing heap churn. + the 'main' fiber is now recycled into the fiber_pool if it leaves app_main() + fibers created through invoke() now only maintains the necessary part of teh parent stack that is needed, thereby reducing the stack size of spawned fibers. - Updates to the Message Bus to reduce the overall memory footprint of processing events. More specifically: + Event handlers are now always called using invoke(), such that non-blocking event handlers no longer need a dedicated fiber to execute - thereby saving SRAM and processor time. + Processing of events from the event queue is now rate paced. Events only continue to be processed as long as there are no fibers on the run queue. i.e. event processing is no longer greedy, thereby reducing the number of fibers created on the runqueue. - Updates to BLUEZOENE code to bring up core BLE services even if they are not enabled by default. This allows programs that do not require BLE to operate to benefit from the full range of SRAM, whilst still allowing the device to be programmed over BLE. - Updates to the Soft Device initialisation configuration, reducing the size of the GATT table held in the top 1.8K of its 8K memory region to around 800 bytes. This is sufficient to run the default set of BLE services on the micro:bit so the additional memory is configured as HEAP storage by MicroBitHeapAllocator. - Minor changes to a range of components to integrate with the above changes. + rename of free() to release() in DynamicPWM to avoid namespace collision with MicroBitHeap free() + rename of fork_on_block to invoke() to enhance readbility. - Many code cleanups and updates to out of date comments.
2015-08-31 22:25:10 +00:00
* pwm->release();
* @endcode
*/
microbit: Memory Optimisation Mega Update This release contains a widespread set of updates and optimisations to the micro:bit runtime, with a view to reducing the SRAM footprint of the whole system. This is to provide as much usable HEAP storage for application programs as possible. Specific updates and optimisations include: - Additional compilation flags to allow the core micro:bit runtime to be configured. These are defined in MicroBitConfig.h - A custom heap allocator. This is now included for two reasons: 1) To provide a simple mechanism to to utilise both the mbed heap space and other memory regions (such as unused memory in the SoftDevice region) as a single virtual heap. 2) To address some issues that have been noted that are attributable to heap fragmentation. The micro:bit heap allocator has a simple algorithm, but one that is chosen to respond well to the relativelt high 'heap churn' found in the micro:bit environment. All micro:bit components and user programs now use this heap allocator trasparently. - Updates to BLE services to remove persistent references to their GATT services. This consumes vast amounts SRAM, rather unecessarily. Instead only handles to the relevant GATT characteristics are now stored. This specifically includes: + MicroBitDFUService + MicroBitEventService + DeviceInformationService - Updates to the Fiber scheduler to save SRAM. More specifically: + Removed the need to hold an empty processor context to intialise fibers. + The IDLE fiber now runs without a stack + fiber stacks are now only created when a fiber is descheduled for the first time, thereby reducing heap churn. + the 'main' fiber is now recycled into the fiber_pool if it leaves app_main() + fibers created through invoke() now only maintains the necessary part of teh parent stack that is needed, thereby reducing the stack size of spawned fibers. - Updates to the Message Bus to reduce the overall memory footprint of processing events. More specifically: + Event handlers are now always called using invoke(), such that non-blocking event handlers no longer need a dedicated fiber to execute - thereby saving SRAM and processor time. + Processing of events from the event queue is now rate paced. Events only continue to be processed as long as there are no fibers on the run queue. i.e. event processing is no longer greedy, thereby reducing the number of fibers created on the runqueue. - Updates to BLUEZOENE code to bring up core BLE services even if they are not enabled by default. This allows programs that do not require BLE to operate to benefit from the full range of SRAM, whilst still allowing the device to be programmed over BLE. - Updates to the Soft Device initialisation configuration, reducing the size of the GATT table held in the top 1.8K of its 8K memory region to around 800 bytes. This is sufficient to run the default set of BLE services on the micro:bit so the additional memory is configured as HEAP storage by MicroBitHeapAllocator. - Minor changes to a range of components to integrate with the above changes. + rename of free() to release() in DynamicPWM to avoid namespace collision with MicroBitHeap free() + rename of fork_on_block to invoke() to enhance readbility. - Many code cleanups and updates to out of date comments.
2015-08-31 22:25:10 +00:00
void release();
/**
* Retreives the pin name associated with this DynamicPwm instance.
*
* Example:
* @code
* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
* pwm->getPinName(); // equal to n
* @endcode
*/
PinName getPinName();
/**
* Sets the period used by the WHOLE PWM module. Any changes to the period will AFFECT ALL CHANNELS.
*
* Example:
* @code
* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
* pwm->setPeriodUs(1000); // period now is 1ms
* @endcode
*
* @note The display uses the pwm module, if you change this value the display may flicker.
*/
void setPeriodUs(int period);
};
#endif