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

Revision:

0:b9164b348919

diff -r 000000000000 -r b9164b348919 microbit/microbit-dal/source/drivers/MicroBitLightSensor.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/microbit/microbit-dal/source/drivers/MicroBitLightSensor.cpp	Mon Oct 17 12:41:20 2016 +0000
@@ -0,0 +1,180 @@
+/*
+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 MicroBitLightSensor.
+  *
+  * This is an object that interleaves light sensing with MicroBitDisplay.
+  */
+
+#include "MicroBitConfig.h"
+#include "MicroBitLightSensor.h"
+#include "MicroBitDisplay.h"
+
+/**
+  * After the startSensing method has been called, this method will be called
+  * MICROBIT_LIGHT_SENSOR_AN_SET_TIME after.
+  *
+  * It will then read from the currently selected channel using the AnalogIn
+  * that was configured in the startSensing method.
+  */
+void MicroBitLightSensor::analogReady()
+{
+    this->results[chan] = this->sensePin->read_u16();
+
+    analogDisable();
+
+    DigitalOut((PinName)(matrixMap.columnStart + chan)).write(1);
+
+    chan++;
+
+    chan = chan % MICROBIT_LIGHT_SENSOR_CHAN_NUM;
+}
+
+/**
+  * Forcibly disables the AnalogIn, otherwise it will remain in possession
+  * of the GPIO channel it is using, meaning that the display will not be
+  * able to use a channel (COL).
+  *
+  * This is required as per PAN 3, details of which can be found here:
+  *
+  * https://www.nordicsemi.com/eng/nordic/download_resource/24634/5/88440387
+  */
+void MicroBitLightSensor::analogDisable()
+{
+    NRF_ADC->ENABLE = ADC_ENABLE_ENABLE_Disabled;
+
+    NRF_ADC->CONFIG = (ADC_CONFIG_RES_8bit << ADC_CONFIG_RES_Pos) |
+                      (ADC_CONFIG_INPSEL_SupplyTwoThirdsPrescaling << ADC_CONFIG_INPSEL_Pos) |
+                      (ADC_CONFIG_REFSEL_VBG                       << ADC_CONFIG_REFSEL_Pos) |
+                      (ADC_CONFIG_PSEL_Disabled                    << ADC_CONFIG_PSEL_Pos) |
+                      (ADC_CONFIG_EXTREFSEL_None                   << ADC_CONFIG_EXTREFSEL_Pos);
+}
+
+/**
+  * Constructor.
+  *
+  * Create a representation of the light sensor.
+  *
+  * @param map The mapping information that relates pin inputs/outputs to physical screen coordinates.
+  *            Defaults to microbitMatrixMap, defined in MicroBitMatrixMaps.h.
+  */
+MicroBitLightSensor::MicroBitLightSensor(const MatrixMap &map) :
+    analogTrigger(),
+    matrixMap(map)
+{
+    this->chan = 0;
+
+    for(int i = 0; i < MICROBIT_LIGHT_SENSOR_CHAN_NUM; i++)
+        results[i] = 0;
+
+    if (EventModel::defaultEventBus)
+        EventModel::defaultEventBus->listen(MICROBIT_ID_DISPLAY, MICROBIT_DISPLAY_EVT_LIGHT_SENSE, this, &MicroBitLightSensor::startSensing, MESSAGE_BUS_LISTENER_IMMEDIATE);
+
+    this->sensePin = NULL;
+}
+
+/**
+  * This method returns a summed average of the three sections of the display.
+  *
+  * A section is defined as:
+  *  ___________________
+  * | 1 |   | 2 |   | 3 |
+  * |___|___|___|___|___|
+  * |   |   |   |   |   |
+  * |___|___|___|___|___|
+  * | 2 |   | 3 |   | 1 |
+  * |___|___|___|___|___|
+  * |   |   |   |   |   |
+  * |___|___|___|___|___|
+  * | 3 |   | 1 |   | 2 |
+  * |___|___|___|___|___|
+  *
+  * Where each number represents a different section on the 5 x 5 matrix display.
+  *
+  * @return returns a value in the range 0 - 255 where 0 is dark, and 255
+  * is very bright
+  */
+int MicroBitLightSensor::read()
+{
+    int sum = 0;
+
+    for(int i = 0; i < MICROBIT_LIGHT_SENSOR_CHAN_NUM; i++)
+        sum += results[i];
+
+    int average = sum / MICROBIT_LIGHT_SENSOR_CHAN_NUM;
+
+    average = min(average, MICROBIT_LIGHT_SENSOR_MAX_VALUE);
+
+    average = max(average, MICROBIT_LIGHT_SENSOR_MIN_VALUE);
+
+    int inverted = (MICROBIT_LIGHT_SENSOR_MAX_VALUE - average) + MICROBIT_LIGHT_SENSOR_MIN_VALUE;
+
+    int a = 0;
+
+    int b = 255;
+
+    int normalised = a + ((((inverted - MICROBIT_LIGHT_SENSOR_MIN_VALUE)) * (b - a))/ (MICROBIT_LIGHT_SENSOR_MAX_VALUE - MICROBIT_LIGHT_SENSOR_MIN_VALUE));
+
+    return normalised;
+}
+
+/**
+  * The method that is invoked by sending MICROBIT_DISPLAY_EVT_LIGHT_SENSE
+  * using the id MICROBIT_ID_DISPLAY.
+  *
+  * @note this can be manually driven by calling this member function, with
+  *       a MicroBitEvent using the CREATE_ONLY option of the MicroBitEvent
+  *       constructor.
+  */
+void MicroBitLightSensor::startSensing(MicroBitEvent)
+{
+    for(int rowCount = 0; rowCount < matrixMap.rows; rowCount++)
+        DigitalOut((PinName)(matrixMap.rowStart + rowCount)).write(0);
+
+    PinName currentPin = (PinName)(matrixMap.columnStart + chan);
+
+    DigitalOut(currentPin).write(1);
+
+    DigitalIn(currentPin, PullNone).~DigitalIn();
+
+    if(this->sensePin != NULL)
+        delete this->sensePin;
+
+    this->sensePin = new AnalogIn(currentPin);
+
+    analogTrigger.attach_us(this, &MicroBitLightSensor::analogReady, MICROBIT_LIGHT_SENSOR_AN_SET_TIME);
+}
+
+/**
+  * A destructor for MicroBitLightSensor.
+  *
+  * The destructor removes the listener, used by MicroBitLightSensor from the default EventModel.
+  */
+MicroBitLightSensor::~MicroBitLightSensor()
+{
+    if (EventModel::defaultEventBus)
+        EventModel::defaultEventBus->ignore(MICROBIT_ID_DISPLAY, MICROBIT_DISPLAY_EVT_LIGHT_SENSE, this, &MicroBitLightSensor::startSensing);
+}
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