Diff: microbit/microbit-dal/source/drivers/MicroBitPin.cpp

Revision:

0:b9164b348919

diff -r 000000000000 -r b9164b348919 microbit/microbit-dal/source/drivers/MicroBitPin.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/microbit/microbit-dal/source/drivers/MicroBitPin.cpp	Mon Oct 17 12:41:20 2016 +0000
@@ -0,0 +1,634 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 British Broadcasting Corporation.
+This software is provided by Lancaster University by arrangement with the BBC.
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+/**
+  * Class definition for MicroBitPin.
+  *
+  * Commonly represents an I/O pin on the edge connector.
+  */
+#include "MicroBitConfig.h"
+#include "MicroBitPin.h"
+#include "MicroBitButton.h"
+#include "MicroBitSystemTimer.h"
+#include "TimedInterruptIn.h"
+#include "DynamicPwm.h"
+#include "ErrorNo.h"
+
+/**
+  * Constructor.
+  * Create a MicroBitPin instance, generally used to represent a pin on the edge connector.
+  *
+  * @param id the unique EventModel id of this component.
+  *
+  * @param name the mbed PinName for this MicroBitPin instance.
+  *
+  * @param capability the capabilities this MicroBitPin instance should have.
+  *                   (PIN_CAPABILITY_DIGITAL, PIN_CAPABILITY_ANALOG, PIN_CAPABILITY_AD, PIN_CAPABILITY_ALL)
+  *
+  * @code
+  * MicroBitPin P0(MICROBIT_ID_IO_P0, MICROBIT_PIN_P0, PIN_CAPABILITY_ALL);
+  * @endcode
+  */
+MicroBitPin::MicroBitPin(int id, PinName name, PinCapability capability)
+{
+    //set mandatory attributes
+    this->id = id;
+    this->name = name;
+    this->capability = capability;
+    this->pullMode = MICROBIT_DEFAULT_PULLMODE;
+
+    // Power up in a disconnected, low power state.
+    // If we're unused, this is how it will stay...
+    this->status = 0x00;
+    this->pin = NULL;
+
+}
+
+/**
+  * Disconnect any attached mBed IO from this pin.
+  *
+  * Used only when pin changes mode (i.e. Input/Output/Analog/Digital)
+  */
+void MicroBitPin::disconnect()
+{
+    // This is a bit ugly, but rarely used code.
+    // It would be much better to use some polymorphism here, but the mBed I/O classes aren't arranged in an inheritance hierarchy... yet. :-)
+    if (status & IO_STATUS_DIGITAL_IN)
+        delete ((DigitalIn *)pin);
+
+    if (status & IO_STATUS_DIGITAL_OUT)
+        delete ((DigitalOut *)pin);
+
+    if (status & IO_STATUS_ANALOG_IN){
+        NRF_ADC->ENABLE = ADC_ENABLE_ENABLE_Disabled; // forcibly disable the ADC - BUG in mbed....
+        delete ((AnalogIn *)pin);
+    }
+
+    if (status & IO_STATUS_ANALOG_OUT)
+    {
+        if(((DynamicPwm *)pin)->getPinName() == name)
+            ((DynamicPwm *)pin)->release();
+    }
+
+    if (status & IO_STATUS_TOUCH_IN)
+        delete ((MicroBitButton *)pin);
+
+    if ((status & IO_STATUS_EVENT_ON_EDGE) || (status & IO_STATUS_EVENT_PULSE_ON_EDGE))
+        delete ((TimedInterruptIn *)pin);
+
+    this->pin = NULL;
+    this->status = 0;
+}
+
+/**
+  * Configures this IO pin as a digital output (if necessary) and sets the pin to 'value'.
+  *
+  * @param value 0 (LO) or 1 (HI)
+  *
+  * @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER if value is out of range, or MICROBIT_NOT_SUPPORTED
+  *         if the given pin does not have digital capability.
+  *
+  * @code
+  * MicroBitPin P0(MICROBIT_ID_IO_P0, MICROBIT_PIN_P0, PIN_CAPABILITY_BOTH);
+  * P0.setDigitalValue(1); // P0 is now HI
+  * @endcode
+  */
+int MicroBitPin::setDigitalValue(int value)
+{
+    // Check if this pin has a digital mode...
+    if(!(PIN_CAPABILITY_DIGITAL & capability))
+        return MICROBIT_NOT_SUPPORTED;
+
+    // Ensure we have a valid value.
+    if (value < 0 || value > 1)
+        return MICROBIT_INVALID_PARAMETER;
+
+    // Move into a Digital input state if necessary.
+    if (!(status & IO_STATUS_DIGITAL_OUT)){
+        disconnect();
+        pin = new DigitalOut(name);
+        status |= IO_STATUS_DIGITAL_OUT;
+    }
+
+    // Write the value.
+    ((DigitalOut *)pin)->write(value);
+
+    return MICROBIT_OK;
+}
+
+/**
+  * Configures this IO pin as a digital input (if necessary) and tests its current value.
+  *
+  *
+  * @return 1 if this input is high, 0 if input is LO, or MICROBIT_NOT_SUPPORTED
+  *         if the given pin does not have digital capability.
+  *
+  * @code
+  * MicroBitPin P0(MICROBIT_ID_IO_P0, MICROBIT_PIN_P0, PIN_CAPABILITY_BOTH);
+  * P0.getDigitalValue(); // P0 is either 0 or 1;
+  * @endcode
+  */
+int MicroBitPin::getDigitalValue()
+{
+    //check if this pin has a digital mode...
+    if(!(PIN_CAPABILITY_DIGITAL & capability))
+        return MICROBIT_NOT_SUPPORTED;
+
+    // Move into a Digital input state if necessary.
+    if (!(status & (IO_STATUS_DIGITAL_IN | IO_STATUS_EVENT_ON_EDGE | IO_STATUS_EVENT_PULSE_ON_EDGE)))
+    {
+        disconnect();
+        pin = new DigitalIn(name, (PinMode)pullMode);
+        status |= IO_STATUS_DIGITAL_IN;
+    }
+
+    if(status & (IO_STATUS_EVENT_ON_EDGE | IO_STATUS_EVENT_PULSE_ON_EDGE))
+        return ((TimedInterruptIn *)pin)->read();
+
+    return ((DigitalIn *)pin)->read();
+}
+
+/**
+ * Configures this IO pin as a digital input with the specified internal pull-up/pull-down configuraiton (if necessary) and tests its current value.
+ *
+ * @param pull one of the mbed pull configurations: PullUp, PullDown, PullNone
+ *
+ * @return 1 if this input is high, 0 if input is LO, or MICROBIT_NOT_SUPPORTED
+ *         if the given pin does not have digital capability.
+ *
+ * @code
+ * MicroBitPin P0(MICROBIT_ID_IO_P0, MICROBIT_PIN_P0, PIN_CAPABILITY_BOTH);
+ * P0.getDigitalValue(PullUp); // P0 is either 0 or 1;
+ * @endcode
+ */
+int MicroBitPin::getDigitalValue(PinMode pull)
+{
+    setPull(pull);
+    return getDigitalValue();
+}
+
+int MicroBitPin::obtainAnalogChannel()
+{
+    // Move into an analogue input state if necessary, if we are no longer the focus of a DynamicPWM instance, allocate ourselves again!
+    if (!(status & IO_STATUS_ANALOG_OUT) || !(((DynamicPwm *)pin)->getPinName() == name)){
+        disconnect();
+        pin = (void *)DynamicPwm::allocate(name);
+        status |= IO_STATUS_ANALOG_OUT;
+    }
+
+    return MICROBIT_OK;
+}
+
+/**
+  * Configures this IO pin as an analog/pwm output, and change the output value to the given level.
+  *
+  * @param value the level to set on the output pin, in the range 0 - 1024
+  *
+  * @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER if value is out of range, or MICROBIT_NOT_SUPPORTED
+  *         if the given pin does not have analog capability.
+  */
+int MicroBitPin::setAnalogValue(int value)
+{
+    //check if this pin has an analogue mode...
+    if(!(PIN_CAPABILITY_ANALOG & capability))
+        return MICROBIT_NOT_SUPPORTED;
+
+    //sanitise the level value
+    if(value < 0 || value > MICROBIT_PIN_MAX_OUTPUT)
+        return MICROBIT_INVALID_PARAMETER;
+
+    float level = (float)value / float(MICROBIT_PIN_MAX_OUTPUT);
+
+    //obtain use of the DynamicPwm instance, if it has changed / configure if we do not have one
+    if(obtainAnalogChannel() == MICROBIT_OK)
+        return ((DynamicPwm *)pin)->write(level);
+
+    return MICROBIT_OK;
+}
+
+/**
+  * Configures this IO pin as an analog/pwm output (if necessary) and configures the period to be 20ms,
+  * with a duty cycle between 500 us and 2500 us.
+  *
+  * A value of 180 sets the duty cycle to be 2500us, and a value of 0 sets the duty cycle to be 500us by default.
+  *
+  * This range can be modified to fine tune, and also tolerate different servos.
+  *
+  * @param value the level to set on the output pin, in the range 0 - 180.
+  *
+  * @param range which gives the span of possible values the i.e. the lower and upper bounds (center +/- range/2). Defaults to MICROBIT_PIN_DEFAULT_SERVO_RANGE.
+  *
+  * @param center the center point from which to calculate the lower and upper bounds. Defaults to MICROBIT_PIN_DEFAULT_SERVO_CENTER
+  *
+  * @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER if value is out of range, or MICROBIT_NOT_SUPPORTED
+  *         if the given pin does not have analog capability.
+  */
+int MicroBitPin::setServoValue(int value, int range, int center)
+{
+    //check if this pin has an analogue mode...
+    if(!(PIN_CAPABILITY_ANALOG & capability))
+        return MICROBIT_NOT_SUPPORTED;
+
+    //sanitise the servo level
+    if(value < 0 || range < 1 || center < 1)
+        return MICROBIT_INVALID_PARAMETER;
+
+    //clip - just in case
+    if(value > MICROBIT_PIN_MAX_SERVO_RANGE)
+        value = MICROBIT_PIN_MAX_SERVO_RANGE;
+
+    //calculate the lower bound based on the midpoint
+    int lower = (center - (range / 2)) * 1000;
+
+    value = value * 1000;
+
+    //add the percentage of the range based on the value between 0 and 180
+    int scaled = lower + (range * (value / MICROBIT_PIN_MAX_SERVO_RANGE));
+
+    return setServoPulseUs(scaled / 1000);
+}
+
+/**
+  * Configures this IO pin as an analogue input (if necessary), and samples the Pin for its analog value.
+  *
+  * @return the current analogue level on the pin, in the range 0 - 1024, or
+  *         MICROBIT_NOT_SUPPORTED if the given pin does not have analog capability.
+  *
+  * @code
+  * MicroBitPin P0(MICROBIT_ID_IO_P0, MICROBIT_PIN_P0, PIN_CAPABILITY_BOTH);
+  * P0.getAnalogValue(); // P0 is a value in the range of 0 - 1024
+  * @endcode
+  */
+int MicroBitPin::getAnalogValue()
+{
+    //check if this pin has an analogue mode...
+    if(!(PIN_CAPABILITY_ANALOG & capability))
+        return MICROBIT_NOT_SUPPORTED;
+
+    // Move into an analogue input state if necessary.
+    if (!(status & IO_STATUS_ANALOG_IN)){
+        disconnect();
+        pin = new AnalogIn(name);
+        status |= IO_STATUS_ANALOG_IN;
+    }
+
+    //perform a read!
+    return ((AnalogIn *)pin)->read_u16();
+}
+
+/**
+  * Determines if this IO pin is currently configured as an input.
+  *
+  * @return 1 if pin is an analog or digital input, 0 otherwise.
+  */
+int MicroBitPin::isInput()
+{
+    return (status & (IO_STATUS_DIGITAL_IN | IO_STATUS_ANALOG_IN)) == 0 ? 0 : 1;
+}
+
+/**
+  * Determines if this IO pin is currently configured as an output.
+  *
+  * @return 1 if pin is an analog or digital output, 0 otherwise.
+  */
+int MicroBitPin::isOutput()
+{
+    return (status & (IO_STATUS_DIGITAL_OUT | IO_STATUS_ANALOG_OUT)) == 0 ? 0 : 1;
+}
+
+/**
+  * Determines if this IO pin is currently configured for digital use.
+  *
+  * @return 1 if pin is digital, 0 otherwise.
+  */
+int MicroBitPin::isDigital()
+{
+    return (status & (IO_STATUS_DIGITAL_IN | IO_STATUS_DIGITAL_OUT)) == 0 ? 0 : 1;
+}
+
+/**
+  * Determines if this IO pin is currently configured for analog use.
+  *
+  * @return 1 if pin is analog, 0 otherwise.
+  */
+int MicroBitPin::isAnalog()
+{
+    return (status & (IO_STATUS_ANALOG_IN | IO_STATUS_ANALOG_OUT)) == 0 ? 0 : 1;
+}
+
+/**
+  * Configures this IO pin as a "makey makey" style touch sensor (if necessary)
+  * and tests its current debounced state.
+  *
+  * Users can also subscribe to MicroBitButton events generated from this pin.
+  *
+  * @return 1 if pin is touched, 0 if not, or MICROBIT_NOT_SUPPORTED if this pin does not support touch capability.
+  *
+  * @code
+  * MicroBitMessageBus bus;
+  *
+  * MicroBitPin P0(MICROBIT_ID_IO_P0, MICROBIT_PIN_P0, PIN_CAPABILITY_ALL);
+  * if(P0.isTouched())
+  * {
+  *     //do something!
+  * }
+  *
+  * // subscribe to events generated by this pin!
+  * bus.listen(MICROBIT_ID_IO_P0, MICROBIT_BUTTON_EVT_CLICK, someFunction);
+  * @endcode
+  */
+int MicroBitPin::isTouched()
+{
+    //check if this pin has a touch mode...
+    if(!(PIN_CAPABILITY_DIGITAL & capability))
+        return MICROBIT_NOT_SUPPORTED;
+
+    // Move into a touch input state if necessary.
+    if (!(status & IO_STATUS_TOUCH_IN)){
+        disconnect();
+        pin = new MicroBitButton(name, id);
+        status |= IO_STATUS_TOUCH_IN;
+    }
+
+    return ((MicroBitButton *)pin)->isPressed();
+}
+
+/**
+  * Configures this IO pin as an analog/pwm output if it isn't already, configures the period to be 20ms,
+  * and sets the pulse width, based on the value it is given.
+  *
+  * @param pulseWidth the desired pulse width in microseconds.
+  *
+  * @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER if value is out of range, or MICROBIT_NOT_SUPPORTED
+  *         if the given pin does not have analog capability.
+  */
+int MicroBitPin::setServoPulseUs(int pulseWidth)
+{
+    //check if this pin has an analogue mode...
+    if(!(PIN_CAPABILITY_ANALOG & capability))
+        return MICROBIT_NOT_SUPPORTED;
+
+    //sanitise the pulse width
+    if(pulseWidth < 0)
+        return MICROBIT_INVALID_PARAMETER;
+
+    //Check we still have the control over the DynamicPwm instance
+    if(obtainAnalogChannel() == MICROBIT_OK)
+    {
+        //check if the period is set to 20ms
+        if(((DynamicPwm *)pin)->getPeriodUs() != MICROBIT_DEFAULT_PWM_PERIOD)
+            ((DynamicPwm *)pin)->setPeriodUs(MICROBIT_DEFAULT_PWM_PERIOD);
+
+        ((DynamicPwm *)pin)->pulsewidth_us(pulseWidth);
+    }
+
+    return MICROBIT_OK;
+}
+
+/**
+  * Configures the PWM period of the analog output to the given value.
+  *
+  * @param period The new period for the analog output in microseconds.
+  *
+  * @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the
+  *         given pin is not configured as an analog output.
+  */
+int MicroBitPin::setAnalogPeriodUs(int period)
+{
+    if (!(status & IO_STATUS_ANALOG_OUT))
+        return MICROBIT_NOT_SUPPORTED;
+
+    return ((DynamicPwm *)pin)->setPeriodUs(period);
+}
+
+/**
+  * Configures the PWM period of the analog output to the given value.
+  *
+  * @param period The new period for the analog output in milliseconds.
+  *
+  * @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the
+  *         given pin is not configured as an analog output.
+  */
+int MicroBitPin::setAnalogPeriod(int period)
+{
+    return setAnalogPeriodUs(period*1000);
+}
+
+/**
+  * Obtains the PWM period of the analog output in microseconds.
+  *
+  * @return the period on success, or MICROBIT_NOT_SUPPORTED if the
+  *         given pin is not configured as an analog output.
+  */
+int MicroBitPin::getAnalogPeriodUs()
+{
+    if (!(status & IO_STATUS_ANALOG_OUT))
+        return MICROBIT_NOT_SUPPORTED;
+
+    return ((DynamicPwm *)pin)->getPeriodUs();
+}
+
+/**
+  * Obtains the PWM period of the analog output in milliseconds.
+  *
+  * @return the period on success, or MICROBIT_NOT_SUPPORTED if the
+  *         given pin is not configured as an analog output.
+  */
+int MicroBitPin::getAnalogPeriod()
+{
+    return getAnalogPeriodUs()/1000;
+}
+
+/**
+  * Configures the pull of this pin.
+  *
+  * @param pull one of the mbed pull configurations: PullUp, PullDown, PullNone
+  *
+  * @return MICROBIT_NOT_SUPPORTED if the current pin configuration is anything other
+  *         than a digital input, otherwise MICROBIT_OK.
+  */
+int MicroBitPin::setPull(PinMode pull)
+{
+    pullMode = pull;
+
+    if ((status & IO_STATUS_DIGITAL_IN))
+    {
+        ((DigitalIn *)pin)->mode(pull);
+        return MICROBIT_OK;
+    }
+
+    if((status & IO_STATUS_EVENT_ON_EDGE) || (status & IO_STATUS_EVENT_PULSE_ON_EDGE))
+    {
+        ((TimedInterruptIn *)pin)->mode(pull);
+        return MICROBIT_OK;
+    }
+
+    return MICROBIT_NOT_SUPPORTED;
+}
+
+/**
+  * This member function manages the calculation of the timestamp of a pulse detected
+  * on a pin whilst in IO_STATUS_EVENT_PULSE_ON_EDGE or IO_STATUS_EVENT_ON_EDGE modes.
+  *
+  * @param eventValue the event value to distribute onto the message bus.
+  */
+void MicroBitPin::pulseWidthEvent(int eventValue)
+{
+    MicroBitEvent evt(id, eventValue, CREATE_ONLY);
+    uint64_t now = evt.timestamp;
+    uint64_t previous = ((TimedInterruptIn *)pin)->getTimestamp();
+
+    if (previous != 0)
+    {
+        evt.timestamp -= previous;
+        evt.fire();
+    }
+
+    ((TimedInterruptIn *)pin)->setTimestamp(now);
+}
+
+/**
+  * Interrupt handler for when an rise interrupt is triggered.
+  */
+void MicroBitPin::onRise()
+{
+    if(status & IO_STATUS_EVENT_PULSE_ON_EDGE)
+        pulseWidthEvent(MICROBIT_PIN_EVT_PULSE_LO);
+
+    if(status & IO_STATUS_EVENT_ON_EDGE)
+        MicroBitEvent(id, MICROBIT_PIN_EVT_RISE);
+}
+
+/**
+  * Interrupt handler for when an fall interrupt is triggered.
+  */
+void MicroBitPin::onFall()
+{
+    if(status & IO_STATUS_EVENT_PULSE_ON_EDGE)
+        pulseWidthEvent(MICROBIT_PIN_EVT_PULSE_HI);
+
+    if(status & IO_STATUS_EVENT_ON_EDGE)
+        MicroBitEvent(id, MICROBIT_PIN_EVT_FALL);
+}
+
+/**
+  * This member function will construct an TimedInterruptIn instance, and configure
+  * interrupts for rise and fall.
+  *
+  * @param eventType the specific mode used in interrupt context to determine how an
+  *                  edge/rise is processed.
+  *
+  * @return MICROBIT_OK on success
+  */
+int MicroBitPin::enableRiseFallEvents(int eventType)
+{
+    // if we are in neither of the two modes, configure pin as a TimedInterruptIn.
+    if (!(status & (IO_STATUS_EVENT_ON_EDGE | IO_STATUS_EVENT_PULSE_ON_EDGE)))
+    {
+        disconnect();
+        pin = new TimedInterruptIn(name);
+
+        ((TimedInterruptIn *)pin)->mode((PinMode)pullMode);
+        ((TimedInterruptIn *)pin)->rise(this, &MicroBitPin::onRise);
+        ((TimedInterruptIn *)pin)->fall(this, &MicroBitPin::onFall);
+    }
+
+    status &= ~(IO_STATUS_EVENT_ON_EDGE | IO_STATUS_EVENT_PULSE_ON_EDGE);
+
+    // set our status bits accordingly.
+    if(eventType == MICROBIT_PIN_EVENT_ON_EDGE)
+        status |= IO_STATUS_EVENT_ON_EDGE;
+    else if(eventType == MICROBIT_PIN_EVENT_ON_PULSE)
+        status |= IO_STATUS_EVENT_PULSE_ON_EDGE;
+
+    return MICROBIT_OK;
+}
+
+/**
+  * If this pin is in a mode where the pin is generating events, it will destruct
+  * the current instance attached to this MicroBitPin instance.
+  *
+  * @return MICROBIT_OK on success.
+  */
+int MicroBitPin::disableEvents()
+{
+    if (status & (IO_STATUS_EVENT_ON_EDGE | IO_STATUS_EVENT_PULSE_ON_EDGE | IO_STATUS_TOUCH_IN))
+        disconnect();
+
+    return MICROBIT_OK;
+}
+
+/**
+  * Configures the events generated by this MicroBitPin instance.
+  *
+  * MICROBIT_PIN_EVENT_ON_EDGE - Configures this pin to a digital input, and generates events whenever a rise/fall is detected on this pin. (MICROBIT_PIN_EVT_RISE, MICROBIT_PIN_EVT_FALL)
+  * MICROBIT_PIN_EVENT_ON_PULSE - Configures this pin to a digital input, and generates events where the timestamp is the duration that this pin was either HI or LO. (MICROBIT_PIN_EVT_PULSE_HI, MICROBIT_PIN_EVT_PULSE_LO)
+  * MICROBIT_PIN_EVENT_ON_TOUCH - Configures this pin as a makey makey style touch sensor, in the form of a MicroBitButton. Normal button events will be generated using the ID of this pin.
+  * MICROBIT_PIN_EVENT_NONE - Disables events for this pin.
+  *
+  * @param eventType One of: MICROBIT_PIN_EVENT_ON_EDGE, MICROBIT_PIN_EVENT_ON_PULSE, MICROBIT_PIN_EVENT_ON_TOUCH, MICROBIT_PIN_EVENT_NONE
+  *
+  * @code
+  * MicroBitMessageBus bus;
+  *
+  * MicroBitPin P0(MICROBIT_ID_IO_P0, MICROBIT_PIN_P0, PIN_CAPABILITY_BOTH);
+  * P0.eventOn(MICROBIT_PIN_EVENT_ON_PULSE);
+  *
+  * void onPulse(MicroBitEvent evt)
+  * {
+  *     int duration = evt.timestamp;
+  * }
+  *
+  * bus.listen(MICROBIT_ID_IO_P0, MICROBIT_PIN_EVT_PULSE_HI, onPulse, MESSAGE_BUS_LISTENER_IMMEDIATE)
+  * @endcode
+  *
+  * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the given eventype does not match
+  *
+  * @note In the MICROBIT_PIN_EVENT_ON_PULSE mode, the smallest pulse that was reliably detected was 85us, around 5khz. If more precision is required,
+  *       please use the InterruptIn class supplied by ARM mbed.
+  */
+int MicroBitPin::eventOn(int eventType)
+{
+    switch(eventType)
+    {
+        case MICROBIT_PIN_EVENT_ON_EDGE:
+        case MICROBIT_PIN_EVENT_ON_PULSE:
+            enableRiseFallEvents(eventType);
+            break;
+
+        case MICROBIT_PIN_EVENT_ON_TOUCH:
+            isTouched();
+            break;
+
+        case MICROBIT_PIN_EVENT_NONE:
+            disableEvents();
+            break;
+
+        default:
+            return MICROBIT_INVALID_PARAMETER;
+    }
+
+    return MICROBIT_OK;
+}
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