MicrobitUltrasound.cpp

00001 /*
00002    The MIT License (MIT)
00003 
00004    Copyright (c) 2016 British Broadcasting Corporation.
00005    This software is provided by Lancaster University by arrangement with the BBC.
00006 
00007    Permission is hereby granted, free of charge, to any person obtaining a
00008    copy of this software and associated documentation files (the "Software"),
00009    to deal in the Software without restriction, including without limitation
00010    the rights to use, copy, modify, merge, publish, distribute, sublicense,
00011    and/or sell copies of the Software, and to permit persons to whom the
00012    Software is furnished to do so, subject to the following conditions:
00013 
00014    The above copyright notice and this permission notice shall be included in
00015    all copies or substantial portions of the Software.
00016 
00017    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00018    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00019    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
00020    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00021    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
00022    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
00023    DEALINGS IN THE SOFTWARE.
00024    */
00025 
00026 /**
00027  * Class definition for MicroBitPin.
00028  *
00029  * Commonly represents an I/O pin on the edge connector.
00030  */
00031 #include "MicrobitUltrasound.h"
00032 #include "MicroBitSystemTimer.h"
00033 #include "MicroBitFiber.h"
00034 
00035   /**
00036    * Constructor.
00037    * Create new MicrobitUltrasound that reports distance to closest object
00038    *
00039    * @param triggerPinName Name of the MicroBitPin to be used as trigger.
00040    *
00041    * @param echoPinName Name of the MicroBitPin to be used as response from sensor.
00042    *
00043    * @code
00044    * MicrobitUltrasound uSoundSensor(MICROBIT_PIN_P1, 100, true, MICROBIT_PIN_P2, PullUp);
00045    * @endcode
00046    */
00047 MicrobitUltrasound::MicrobitUltrasound(PinName triggerPinName, int _triggerPeriod_ms, bool _triggerActiveValue, 
00048     PinName echoPinName, PinMode echoPinMode, uint16_t id):
00049   trigger(triggerPinName), echo(echoPinName)
00050 {
00051   this->id                 = id;
00052   this->status             = 0;
00053   this->sampleTime         = 0;
00054   this->triggerDuration_us = MICROBIT_ULTRASOUND_TRIGGER_DURATION_DEFAULT_US;
00055   this->triggerPeriod_ms   = (uint16_t)_triggerPeriod_ms;
00056   this->triggerActiveValue = _triggerActiveValue;
00057 
00058   echo.mode(echoPinMode);
00059   echo.rise(this, &MicrobitUltrasound::onEchoRise);
00060   echo.fall(this, &MicrobitUltrasound::onEchoFall);
00061 }
00062 
00063   /**
00064    * Constructor.
00065    * Create new MicrobitUltrasound that reports distance to closest object
00066    *
00067    * @param triggerPinName Name of the MicroBitPin to be used as trigger.
00068    *
00069    * @param echoPinName Name of the MicroBitPin to be used as response from sensor.
00070    *
00071    * @code
00072    * MicrobitUltrasound uSoundSensor(MICROBIT_PIN_P1, MICROBIT_PIN_P2);
00073    * @endcode
00074    */
00075 MicrobitUltrasound::MicrobitUltrasound(PinName triggerPinName, PinName echoPinName, uint16_t id):
00076   trigger(triggerPinName), echo(echoPinName)
00077 {
00078   this->id                 = id;
00079   this->status             = 0;
00080   this->sampleTime         = 0;
00081   this->triggerPeriod_ms   = MICROBIT_ULTRASOUND_PERIOD_DEFAULT_MS;
00082   this->triggerDuration_us = MICROBIT_ULTRASOUND_TRIGGER_DURATION_DEFAULT_US;
00083   this->triggerActiveValue = TRIGGER_ACTIVE_VALUE;
00084 
00085   //echo.mode((PinMode)MICROBIT_ULTRASOUND_PULLMODE_DEFAULT);
00086   echo.rise(this, &MicrobitUltrasound::onEchoRise);
00087   echo.fall(this, &MicrobitUltrasound::onEchoFall);
00088 }
00089 
00090 /**
00091   * Destructor for MicrobitUltrasound, where we deregister from the array of fiber components.
00092   */
00093 MicrobitUltrasound::~MicrobitUltrasound()
00094 {
00095     fiber_remove_idle_component(this);
00096 }
00097 
00098 /**
00099  * Set Echo PinMode
00100  */
00101 void MicrobitUltrasound::setEchoPinMode(PinMode echoPinMode)
00102 {
00103   echo.mode(echoPinMode);
00104 }
00105 
00106 /**
00107  * This member function manages the calculation of the timestamp of a pulse detected
00108  * on the echo pin.
00109  *
00110  * @param eventValue the event value to distribute onto the message bus.
00111  */
00112 void MicrobitUltrasound::pulseWidthEvent(int eventValue)
00113 {
00114   MicroBitEvent evt(id, eventValue, CREATE_ONLY);
00115   uint64_t now      = evt.timestamp;
00116   uint64_t previous = echo.getTimestamp();
00117 
00118   if (previous != 0)
00119   {
00120     evt.timestamp -= previous;
00121     evt.fire();
00122   }
00123 
00124   echo.setTimestamp(now);
00125 }
00126 
00127 
00128 /**
00129  * Interrupt handler for when an rise interrupt is triggered.
00130  */
00131 void MicrobitUltrasound::onEchoRise()
00132 {
00133   if(status & ULTRASOUND_STATUS_EVENTON_PULSE)
00134     pulseWidthEvent(MICROBIT_ULTRASOUND_EVT_ECHO_PULSE_LO);
00135 
00136   if(status & ULTRASOUND_STATUS_EVENTON_RISE)
00137     MicroBitEvent(id, MICROBIT_ULTRASOUND_EVT_ECHO_RISE);
00138 
00139   if(status & ULTRASOUND_STATUS_EVENTON_EDGE)
00140     MicroBitEvent(id, MICROBIT_ULTRASOUND_EVT_ECHO_EDGE);
00141 }
00142 
00143 /**
00144  * Interrupt handler for when an fall interrupt is triggered.
00145  */
00146 void MicrobitUltrasound::onEchoFall()
00147 {
00148   if(status & ULTRASOUND_STATUS_EVENTON_PULSE)
00149     pulseWidthEvent(MICROBIT_ULTRASOUND_EVT_ECHO_PULSE_HI);
00150 
00151   if(status & ULTRASOUND_STATUS_EVENTON_FALL)
00152     MicroBitEvent(id, MICROBIT_ULTRASOUND_EVT_ECHO_FALL);
00153 
00154   if(status & ULTRASOUND_STATUS_EVENTON_EDGE)
00155     MicroBitEvent(id, MICROBIT_ULTRASOUND_EVT_ECHO_EDGE);
00156 }
00157 
00158 /**
00159  * Set the sample rate at which the micro:bit triggers sensor (in ms).
00160  *
00161  * The default sample period is 1 second.
00162  *
00163  * @param period the requested time between triggers, in milliseconds.
00164  *
00165  * @note the micro:bit sends triggers in the background.
00166  */
00167 void MicrobitUltrasound::setPeriod(int period_ms)
00168 {
00169   this->triggerPeriod_ms    = period_ms;
00170 }
00171 
00172 /**
00173  * Get the sample rate at which the micro:bit triggers sensor (in ms).
00174  *
00175  * @return period the requested time between triggers, in milliseconds.
00176  */
00177 int MicrobitUltrasound::getPeriod()
00178 {
00179   return (int)triggerPeriod_ms;
00180 }
00181 
00182 /**
00183  * Send trigger to start measurement in sensor
00184  *
00185  * This call also will add the class to fiber components to receive
00186  * one callback only.
00187  *
00188  * @return MICROBIT_OK on success.
00189  */
00190 void MicrobitUltrasound::fireTrigger(void)
00191 {
00192   int actVal, pasVal;
00193   actVal =  triggerActiveValue? 1 : 0;
00194   pasVal =  triggerActiveValue? 0 : 1;
00195   trigger.write(pasVal);
00196   wait_us(MICROBIT_ULTRASOUND_IDLE_DURATION_DEFAULT_US);
00197   trigger.write(actVal);
00198   wait_us(triggerDuration_us);
00199   trigger.write(pasVal);
00200 }
00201 
00202 /**
00203  * Start periodic trigger to sensor. This call also will add the class
00204  * to fiber components for periodic callbacks.
00205  *
00206  * @return MICROBIT_OK on success.
00207  */
00208 int MicrobitUltrasound::start(void)
00209 {
00210   int result;
00211   status |= MICROBIT_COMPONENT_RUNNING;
00212   result = updateSample();
00213   return result;
00214 }
00215 
00216 /**
00217  * Stop periodic trigger to sensor. 
00218  *
00219  * @return MICROBIT_OK on success.
00220  */
00221 int MicrobitUltrasound::stop(void)
00222 {
00223   int result;
00224   status &= !MICROBIT_COMPONENT_RUNNING;
00225   result = fiber_remove_idle_component(this);
00226   return result;
00227 }
00228 
00229 
00230 
00231 /**
00232  * Update Sensor measurement
00233  *
00234  * @return MICROBIT_OK on success.
00235  */
00236 int MicrobitUltrasound::updateSample(void)
00237 {
00238   int result;
00239   if(!(status & ULTRASOUND_STATUS_ADDED_TO_IDLE))
00240   {
00241     // If we're running under a fiber scheduer, register ourselves for a periodic callback to keep our data up to date.
00242     // Otherwise, we do just do this on demand with the trigger function.
00243     result = fiber_add_idle_component(this);
00244     if (result != MICROBIT_OK)
00245       return result;
00246     status |= ULTRASOUND_STATUS_ADDED_TO_IDLE;
00247   }
00248 
00249   // check if we need to update our trigger...
00250   if (isTriggerNeeded())
00251   {
00252     fireTrigger();
00253     // Send an event to indicate that we just sent a new trigger.
00254     if (status & ULTRASOUND_STATUS_EVENTON_TRIGGER)
00255       MicroBitEvent e(id, MICROBIT_ULTRASOUND_EVT_TRIGGER);
00256 
00257     // Schedule our next trigger.
00258     sampleTime = system_timer_current_time() + triggerPeriod_ms;
00259   }
00260 
00261   return MICROBIT_OK;
00262 }
00263 
00264 /**
00265  * Periodic callback from MicroBit idle thread.
00266  */
00267 void MicrobitUltrasound::idleTick()
00268 {
00269   updateSample();
00270 }
00271 
00272 /**
00273  * Determines if we're due to take another trigger
00274  *
00275  * @return 1 if we're due to take a new trigger, 0 otherwise.
00276  */
00277 int MicrobitUltrasound::isTriggerNeeded()
00278 {
00279   return  system_timer_current_time() >= sampleTime;
00280 }
00281 
00282 
00283 /**
00284  * Enables a particular event for the current module
00285  *
00286  * @return 1 if we're due to take a new trigger, 0 otherwise.
00287  */
00288 int MicrobitUltrasound::eventOn(int eventType)
00289 {
00290   switch(eventType)
00291   {
00292     case MICROBIT_ULTRASOUND_EVT_ECHO_PULSE_HI  : status |= ULTRASOUND_STATUS_EVENTON_PULSE;
00293                                                   break;
00294     case MICROBIT_ULTRASOUND_EVT_ECHO_PULSE_LO  : status |= ULTRASOUND_STATUS_EVENTON_PULSE;
00295                                                   break;
00296     case MICROBIT_ULTRASOUND_EVT_TRIGGER        : status |= ULTRASOUND_STATUS_EVENTON_TRIGGER;
00297                                                   break;
00298     case MICROBIT_ULTRASOUND_EVT_ECHO_RISE      : status |= ULTRASOUND_STATUS_EVENTON_RISE;
00299                                                   break;
00300     case MICROBIT_ULTRASOUND_EVT_ECHO_FALL      : status |= ULTRASOUND_STATUS_EVENTON_FALL;
00301                                                   break;
00302     case MICROBIT_ULTRASOUND_EVT_ECHO_EDGE      : status |= ULTRASOUND_STATUS_EVENTON_EDGE;
00303                                                   break;
00304     default                                     : return MICROBIT_INVALID_PARAMETER;
00305                                                   break;
00306   }
00307   return MICROBIT_OK;
00308 }