microbit-dal: swapped pwm implementation for a more stable one
As per issue #218, pwm has always been unstable resulting in a clicking noise atwhen tones are amplified, and twitchy servo controllers. This commit when combined with lancaster-university/mbed-classic#03f4fb and lancaster-university/mbed-classic#be51bd will produce a more stable waveform, whilst also maintaining the behaviour of DynamicPwm which has now been absorbed by the PWM driver itself.
This commit is contained in:
James Devine
parent
350aad7a90
commit
15194f2ed2
3 changed files with 28 additions and 204 deletions
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@ -29,15 +29,8 @@ DEALINGS IN THE SOFTWARE.
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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_DEFAULT_PWM_PERIOD 20000
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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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@ -47,13 +40,10 @@ enum PwmPersistence
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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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static uint16_t sharedPeriod;
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uint8_t flags;
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uint32_t period;
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float lastValue;
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public:
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/**
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* An internal constructor used when allocating a new DynamicPwm instance.
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@ -63,40 +53,7 @@ class DynamicPwm : public PwmOut
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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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*/
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DynamicPwm(PinName pin, PwmPersistence persistence = PWM_PERSISTENCE_TRANSIENT);
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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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*
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* @param pin the desired pin to output a PWM wave.
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*
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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* pwm->redirect(p0); // pwm is now produced on p0
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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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* Creates a new DynamicPwm instance, or reuses an existing instance that
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* has a persistence level of PWM_PERSISTENCE_TRANSIENT.
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*
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* @param pin the name of the pin for the pwm to target
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*
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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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*
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* @return a pointer to the first available free pwm channel - or the first one that can be reallocated. If
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* no channels are available, NULL is returned.
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*
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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);
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DynamicPwm(PinName pin);
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/**
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* Frees this DynamicPwm instance for reuse.
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@ -123,7 +80,7 @@ class DynamicPwm : public PwmOut
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int write(float value);
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/**
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* Retreives the PinName associated with this DynamicPwm instance.
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* Retrieves the PinName associated with this DynamicPwm instance.
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*
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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@ -138,7 +95,7 @@ class DynamicPwm : public PwmOut
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PinName getPinName();
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/**
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* Retreives the last value that has been written to this DynamicPwm instance.
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* Retrieves the last value that has been written to this DynamicPwm instance.
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* in the range 0 - 1023 inclusive.
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*
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* @code
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@ -152,7 +109,7 @@ class DynamicPwm : public PwmOut
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int getValue();
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/**
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* Retreives the current period in use by the entire PWM module in microseconds.
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* Retrieves the current period in use by the entire PWM module in microseconds.
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*
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* Example:
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* @code
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@ -160,7 +117,7 @@ class DynamicPwm : public PwmOut
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* pwm->getPeriod();
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* @endcode
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*/
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int getPeriodUs();
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uint32_t getPeriodUs();
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/**
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* Retreives the current period in use by the entire PWM module in milliseconds.
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@ -174,7 +131,7 @@ class DynamicPwm : public PwmOut
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* pwm->getPeriod();
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* @endcode
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*/
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int getPeriod();
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uint32_t getPeriod();
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/**
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* Sets the period used by the WHOLE PWM module.
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@ -193,7 +150,7 @@ class DynamicPwm : public PwmOut
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*
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* @note Any changes to the period will AFFECT ALL CHANNELS.
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*/
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int setPeriodUs(int period);
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int setPeriodUs(uint32_t period);
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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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@ -210,7 +167,9 @@ class DynamicPwm : public PwmOut
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* pwm->setPeriod(20);
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* @endcode
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*/
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int setPeriod(int period);
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int setPeriod(uint32_t period);
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~DynamicPwm();
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};
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#endif
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@ -35,52 +35,6 @@ DEALINGS IN THE SOFTWARE.
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#include "MicroBitPin.h"
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#include "ErrorNo.h"
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DynamicPwm* DynamicPwm::pwms[NO_PWMS] = { NULL, NULL, NULL };
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uint8_t DynamicPwm::lastUsed = NO_PWMS+1; //set it to out of range i.e. 4 so we know it hasn't been used yet.
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uint16_t DynamicPwm::sharedPeriod = 0; //set the shared period to an unknown state
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/**
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* Reassigns an already operational PWM channel to the given pin.
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*
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* @param pin The desired pin to begin a PWM wave.
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*
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* @param oldPin The pin to stop running a PWM wave.
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*
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* @param channel_number The GPIOTE channel being used to drive this PWM channel
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*
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* TODO: Merge into mbed, at a later date.
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*/
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void gpiote_reinit(PinName pin, PinName oldPin, uint8_t channel_number)
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{
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// Connect GPIO input buffers and configure PWM_OUTPUT_PIN_NUMBER as an output.
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NRF_GPIO->PIN_CNF[pin] = (GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos)
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| (GPIO_PIN_CNF_DRIVE_S0S1 << GPIO_PIN_CNF_DRIVE_Pos)
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| (GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos)
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| (GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos)
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| (GPIO_PIN_CNF_DIR_Output << GPIO_PIN_CNF_DIR_Pos);
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NRF_GPIO->OUTCLR = (1 << oldPin);
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NRF_GPIO->OUTCLR = (1 << pin);
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/* Finally configure the channel as the caller expects. If OUTINIT works, the channel is configured properly.
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If it does not, the channel output inheritance sets the proper level. */
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NRF_GPIOTE->CONFIG[channel_number] = (GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos) |
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((uint32_t)pin << GPIOTE_CONFIG_PSEL_Pos) |
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((uint32_t)GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos) |
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((uint32_t)GPIOTE_CONFIG_OUTINIT_Low << GPIOTE_CONFIG_OUTINIT_Pos); // ((uint32_t)GPIOTE_CONFIG_OUTINIT_High <<
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// GPIOTE_CONFIG_OUTINIT_Pos);//
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/* Three NOPs are required to make sure configuration is written before setting tasks or getting events */
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__NOP();
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__NOP();
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__NOP();
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NRF_TIMER2->CC[channel_number] = 0;
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}
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/**
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* An internal constructor used when allocating a new DynamicPwm instance.
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*
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@ -89,82 +43,9 @@ void gpiote_reinit(PinName pin, PinName oldPin, uint8_t channel_number)
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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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*/
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DynamicPwm::DynamicPwm(PinName pin, PwmPersistence persistence) : PwmOut(pin)
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DynamicPwm::DynamicPwm(PinName pin) : PwmOut(pin)
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{
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this->flags = persistence;
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}
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/**
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* Redirects the pwm channel to point at a different pin.
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*
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* @param pin the desired pin to output a PWM wave.
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*
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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* pwm->redirect(p0); // pwm is now produced on p0
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* @endcode
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*/
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void DynamicPwm::redirect(PinName pin)
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{
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gpiote_reinit(pin, _pwm.pin, (uint8_t)_pwm.pwm);
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this->_pwm.pin = pin;
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}
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/**
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* Creates a new DynamicPwm instance, or reuses an existing instance that
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* has a persistence level of PWM_PERSISTENCE_TRANSIENT.
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*
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* @param pin the name of the pin for the pwm to target
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*
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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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*
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* @return a pointer to the first available free pwm channel - or the first one that can be reallocated. If
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* no channels are available, NULL is returned.
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*
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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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DynamicPwm* DynamicPwm::allocate(PinName pin, PwmPersistence persistence)
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{
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//try to find a blank spot first
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for(int i = 0; i < NO_PWMS; i++)
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{
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if(pwms[i] == NULL)
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{
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lastUsed = i;
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pwms[i] = new DynamicPwm(pin, persistence);
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return pwms[i];
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}
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}
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//no blank spot.. try to find a transient PWM
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int channelIterator = (lastUsed + 1 > NO_PWMS - 1) ? 0 : lastUsed + 1;
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while(channelIterator != lastUsed)
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{
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if(pwms[channelIterator]->flags & PWM_PERSISTENCE_TRANSIENT)
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{
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lastUsed = channelIterator;
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pwms[channelIterator]->flags = persistence;
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pwms[channelIterator]->redirect(pin);
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return pwms[channelIterator];
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}
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channelIterator = (channelIterator + 1 > NO_PWMS - 1) ? 0 : channelIterator + 1;
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}
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//if we haven't found a free one, we must try to allocate the last used...
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if(pwms[lastUsed]->flags & PWM_PERSISTENCE_TRANSIENT)
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{
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pwms[lastUsed]->flags = persistence;
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pwms[lastUsed]->redirect(pin);
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return pwms[lastUsed];
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}
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//well if we have no transient channels - we can't give any away! :( return null
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return (DynamicPwm*)NULL;
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this->period = 0;
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}
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/**
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@ -175,20 +56,10 @@ DynamicPwm* DynamicPwm::allocate(PinName pin, PwmPersistence persistence)
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* pwm->release();
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* @endcode
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*/
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void DynamicPwm::release()
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DynamicPwm::~DynamicPwm()
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{
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//free the pwm instance.
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NRF_GPIOTE->CONFIG[(uint8_t) _pwm.pwm] = 0;
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pwmout_free(&_pwm);
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this->flags = PWM_PERSISTENCE_TRANSIENT;
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//set the pointer to this object to null...
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for(int i =0; i < NO_PWMS; i++)
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if(pwms[i] == this)
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{
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delete pwms[i];
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pwms[i] = NULL;
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}
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}
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/**
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@ -215,7 +86,7 @@ int DynamicPwm::write(float value){
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}
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/**
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* Retreives the PinName associated with this DynamicPwm instance.
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* Retrieves the PinName associated with this DynamicPwm instance.
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*
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* @code
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* DynamicPwm* pwm = DynamicPwm::allocate(PinName n);
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@ -233,7 +104,7 @@ PinName DynamicPwm::getPinName()
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}
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/**
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* Retreives the last value that has been written to this DynamicPwm instance.
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* Retrieves the last value that has been written to this DynamicPwm instance.
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* in the range 0 - 1023 inclusive.
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*
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* @code
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@ -250,7 +121,7 @@ int DynamicPwm::getValue()
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}
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/**
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* Retreives the current period in use by the entire PWM module in microseconds.
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* Retrieves the current period in use by the entire PWM module in microseconds.
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*
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* Example:
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* @code
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@ -258,13 +129,13 @@ int DynamicPwm::getValue()
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* pwm->getPeriod();
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* @endcode
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*/
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int DynamicPwm::getPeriodUs()
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uint32_t DynamicPwm::getPeriodUs()
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{
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return sharedPeriod;
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return period;
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}
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/**
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* Retreives the current period in use by the entire PWM module in milliseconds.
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* Retrieves the current period in use by the entire PWM module in milliseconds.
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*
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* Example:
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* @code
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@ -275,7 +146,7 @@ int DynamicPwm::getPeriodUs()
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* pwm->getPeriod();
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* @endcode
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*/
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int DynamicPwm::getPeriod()
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uint32_t DynamicPwm::getPeriod()
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{
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return getPeriodUs() / 1000;
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}
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@ -297,15 +168,12 @@ int DynamicPwm::getPeriod()
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*
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* @note Any changes to the period will AFFECT ALL CHANNELS.
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*/
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int DynamicPwm::setPeriodUs(int period)
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int DynamicPwm::setPeriodUs(uint32_t period)
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{
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if(period < 0)
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return MICROBIT_INVALID_PARAMETER;
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//#HACK this forces mbed to update the pulse width calculation.
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period_us(period);
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write(lastValue);
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sharedPeriod = period;
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this->period = period;
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return MICROBIT_OK;
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}
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@ -325,7 +193,7 @@ int DynamicPwm::setPeriodUs(int period)
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* pwm->setPeriod(20);
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* @endcode
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*/
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int DynamicPwm::setPeriod(int period)
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int DynamicPwm::setPeriod(uint32_t period)
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{
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return setPeriodUs(period * 1000);
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}
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@ -87,10 +87,7 @@ void MicroBitPin::disconnect()
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}
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if (status & IO_STATUS_ANALOG_OUT)
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{
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if(((DynamicPwm *)pin)->getPinName() == name)
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((DynamicPwm *)pin)->release();
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}
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delete ((DynamicPwm *)pin);
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if (status & IO_STATUS_TOUCH_IN)
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delete ((MicroBitButton *)pin);
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@ -194,7 +191,7 @@ int MicroBitPin::obtainAnalogChannel()
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// Move into an analogue input state if necessary, if we are no longer the focus of a DynamicPWM instance, allocate ourselves again!
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if (!(status & IO_STATUS_ANALOG_OUT) || !(((DynamicPwm *)pin)->getPinName() == name)){
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disconnect();
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pin = (void *)DynamicPwm::allocate(name);
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pin = (void *)new DynamicPwm(name);
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status |= IO_STATUS_ANALOG_OUT;
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}
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