Neil Johnson / microbit-ARMBand

Official Sheffield ARMBand micro:bit program

microbit/microbit-dal/source/drivers/MicroBitLightSensor.cpp@0:b9164b348919, 2016-10-17 (annotated)

Committer:
MrBedfordVan
Date:
Mon Oct 17 12:41:20 2016 +0000
Revision:
0:b9164b348919
Official Sheffield ARMBand Micro:bit program

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MrBedfordVan 0:b9164b348919 1 /*
MrBedfordVan 0:b9164b348919 2 The MIT License (MIT)
MrBedfordVan 0:b9164b348919 3
MrBedfordVan 0:b9164b348919 4 Copyright (c) 2016 British Broadcasting Corporation.
MrBedfordVan 0:b9164b348919 5 This software is provided by Lancaster University by arrangement with the BBC.
MrBedfordVan 0:b9164b348919 6
MrBedfordVan 0:b9164b348919 7 Permission is hereby granted, free of charge, to any person obtaining a
MrBedfordVan 0:b9164b348919 8 copy of this software and associated documentation files (the "Software"),
MrBedfordVan 0:b9164b348919 9 to deal in the Software without restriction, including without limitation
MrBedfordVan 0:b9164b348919 10 the rights to use, copy, modify, merge, publish, distribute, sublicense,
MrBedfordVan 0:b9164b348919 11 and/or sell copies of the Software, and to permit persons to whom the
MrBedfordVan 0:b9164b348919 12 Software is furnished to do so, subject to the following conditions:
MrBedfordVan 0:b9164b348919 13
MrBedfordVan 0:b9164b348919 14 The above copyright notice and this permission notice shall be included in
MrBedfordVan 0:b9164b348919 15 all copies or substantial portions of the Software.
MrBedfordVan 0:b9164b348919 16
MrBedfordVan 0:b9164b348919 17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
MrBedfordVan 0:b9164b348919 18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
MrBedfordVan 0:b9164b348919 19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
MrBedfordVan 0:b9164b348919 20 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
MrBedfordVan 0:b9164b348919 21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
MrBedfordVan 0:b9164b348919 22 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
MrBedfordVan 0:b9164b348919 23 DEALINGS IN THE SOFTWARE.
MrBedfordVan 0:b9164b348919 24 */
MrBedfordVan 0:b9164b348919 25
MrBedfordVan 0:b9164b348919 26 /**
MrBedfordVan 0:b9164b348919 27 * Class definition for MicroBitLightSensor.
MrBedfordVan 0:b9164b348919 28 *
MrBedfordVan 0:b9164b348919 29 * This is an object that interleaves light sensing with MicroBitDisplay.
MrBedfordVan 0:b9164b348919 30 */
MrBedfordVan 0:b9164b348919 31
MrBedfordVan 0:b9164b348919 32 #include "MicroBitConfig.h"
MrBedfordVan 0:b9164b348919 33 #include "MicroBitLightSensor.h"
MrBedfordVan 0:b9164b348919 34 #include "MicroBitDisplay.h"
MrBedfordVan 0:b9164b348919 35
MrBedfordVan 0:b9164b348919 36 /**
MrBedfordVan 0:b9164b348919 37 * After the startSensing method has been called, this method will be called
MrBedfordVan 0:b9164b348919 38 * MICROBIT_LIGHT_SENSOR_AN_SET_TIME after.
MrBedfordVan 0:b9164b348919 39 *
MrBedfordVan 0:b9164b348919 40 * It will then read from the currently selected channel using the AnalogIn
MrBedfordVan 0:b9164b348919 41 * that was configured in the startSensing method.
MrBedfordVan 0:b9164b348919 42 */
MrBedfordVan 0:b9164b348919 43 void MicroBitLightSensor::analogReady()
MrBedfordVan 0:b9164b348919 44 {
MrBedfordVan 0:b9164b348919 45 this->results[chan] = this->sensePin->read_u16();
MrBedfordVan 0:b9164b348919 46
MrBedfordVan 0:b9164b348919 47 analogDisable();
MrBedfordVan 0:b9164b348919 48
MrBedfordVan 0:b9164b348919 49 DigitalOut((PinName)(matrixMap.columnStart + chan)).write(1);
MrBedfordVan 0:b9164b348919 50
MrBedfordVan 0:b9164b348919 51 chan++;
MrBedfordVan 0:b9164b348919 52
MrBedfordVan 0:b9164b348919 53 chan = chan % MICROBIT_LIGHT_SENSOR_CHAN_NUM;
MrBedfordVan 0:b9164b348919 54 }
MrBedfordVan 0:b9164b348919 55
MrBedfordVan 0:b9164b348919 56 /**
MrBedfordVan 0:b9164b348919 57 * Forcibly disables the AnalogIn, otherwise it will remain in possession
MrBedfordVan 0:b9164b348919 58 * of the GPIO channel it is using, meaning that the display will not be
MrBedfordVan 0:b9164b348919 59 * able to use a channel (COL).
MrBedfordVan 0:b9164b348919 60 *
MrBedfordVan 0:b9164b348919 61 * This is required as per PAN 3, details of which can be found here:
MrBedfordVan 0:b9164b348919 62 *
MrBedfordVan 0:b9164b348919 63 * https://www.nordicsemi.com/eng/nordic/download_resource/24634/5/88440387
MrBedfordVan 0:b9164b348919 64 */
MrBedfordVan 0:b9164b348919 65 void MicroBitLightSensor::analogDisable()
MrBedfordVan 0:b9164b348919 66 {
MrBedfordVan 0:b9164b348919 67 NRF_ADC->ENABLE = ADC_ENABLE_ENABLE_Disabled;
MrBedfordVan 0:b9164b348919 68
MrBedfordVan 0:b9164b348919 69 NRF_ADC->CONFIG = (ADC_CONFIG_RES_8bit << ADC_CONFIG_RES_Pos) |
MrBedfordVan 0:b9164b348919 70 (ADC_CONFIG_INPSEL_SupplyTwoThirdsPrescaling << ADC_CONFIG_INPSEL_Pos) |
MrBedfordVan 0:b9164b348919 71 (ADC_CONFIG_REFSEL_VBG << ADC_CONFIG_REFSEL_Pos) |
MrBedfordVan 0:b9164b348919 72 (ADC_CONFIG_PSEL_Disabled << ADC_CONFIG_PSEL_Pos) |
MrBedfordVan 0:b9164b348919 73 (ADC_CONFIG_EXTREFSEL_None << ADC_CONFIG_EXTREFSEL_Pos);
MrBedfordVan 0:b9164b348919 74 }
MrBedfordVan 0:b9164b348919 75
MrBedfordVan 0:b9164b348919 76 /**
MrBedfordVan 0:b9164b348919 77 * Constructor.
MrBedfordVan 0:b9164b348919 78 *
MrBedfordVan 0:b9164b348919 79 * Create a representation of the light sensor.
MrBedfordVan 0:b9164b348919 80 *
MrBedfordVan 0:b9164b348919 81 * @param map The mapping information that relates pin inputs/outputs to physical screen coordinates.
MrBedfordVan 0:b9164b348919 82 * Defaults to microbitMatrixMap, defined in MicroBitMatrixMaps.h.
MrBedfordVan 0:b9164b348919 83 */
MrBedfordVan 0:b9164b348919 84 MicroBitLightSensor::MicroBitLightSensor(const MatrixMap &map) :
MrBedfordVan 0:b9164b348919 85 analogTrigger(),
MrBedfordVan 0:b9164b348919 86 matrixMap(map)
MrBedfordVan 0:b9164b348919 87 {
MrBedfordVan 0:b9164b348919 88 this->chan = 0;
MrBedfordVan 0:b9164b348919 89
MrBedfordVan 0:b9164b348919 90 for(int i = 0; i < MICROBIT_LIGHT_SENSOR_CHAN_NUM; i++)
MrBedfordVan 0:b9164b348919 91 results[i] = 0;
MrBedfordVan 0:b9164b348919 92
MrBedfordVan 0:b9164b348919 93 if (EventModel::defaultEventBus)
MrBedfordVan 0:b9164b348919 94 EventModel::defaultEventBus->listen(MICROBIT_ID_DISPLAY, MICROBIT_DISPLAY_EVT_LIGHT_SENSE, this, &MicroBitLightSensor::startSensing, MESSAGE_BUS_LISTENER_IMMEDIATE);
MrBedfordVan 0:b9164b348919 95
MrBedfordVan 0:b9164b348919 96 this->sensePin = NULL;
MrBedfordVan 0:b9164b348919 97 }
MrBedfordVan 0:b9164b348919 98
MrBedfordVan 0:b9164b348919 99 /**
MrBedfordVan 0:b9164b348919 100 * This method returns a summed average of the three sections of the display.
MrBedfordVan 0:b9164b348919 101 *
MrBedfordVan 0:b9164b348919 102 * A section is defined as:
MrBedfordVan 0:b9164b348919 103 * ___________________
MrBedfordVan 0:b9164b348919 104 * | 1 | | 2 | | 3 |
MrBedfordVan 0:b9164b348919 105 * |___|___|___|___|___|
MrBedfordVan 0:b9164b348919 106 * | | | | | |
MrBedfordVan 0:b9164b348919 107 * |___|___|___|___|___|
MrBedfordVan 0:b9164b348919 108 * | 2 | | 3 | | 1 |
MrBedfordVan 0:b9164b348919 109 * |___|___|___|___|___|
MrBedfordVan 0:b9164b348919 110 * | | | | | |
MrBedfordVan 0:b9164b348919 111 * |___|___|___|___|___|
MrBedfordVan 0:b9164b348919 112 * | 3 | | 1 | | 2 |
MrBedfordVan 0:b9164b348919 113 * |___|___|___|___|___|
MrBedfordVan 0:b9164b348919 114 *
MrBedfordVan 0:b9164b348919 115 * Where each number represents a different section on the 5 x 5 matrix display.
MrBedfordVan 0:b9164b348919 116 *
MrBedfordVan 0:b9164b348919 117 * @return returns a value in the range 0 - 255 where 0 is dark, and 255
MrBedfordVan 0:b9164b348919 118 * is very bright
MrBedfordVan 0:b9164b348919 119 */
MrBedfordVan 0:b9164b348919 120 int MicroBitLightSensor::read()
MrBedfordVan 0:b9164b348919 121 {
MrBedfordVan 0:b9164b348919 122 int sum = 0;
MrBedfordVan 0:b9164b348919 123
MrBedfordVan 0:b9164b348919 124 for(int i = 0; i < MICROBIT_LIGHT_SENSOR_CHAN_NUM; i++)
MrBedfordVan 0:b9164b348919 125 sum += results[i];
MrBedfordVan 0:b9164b348919 126
MrBedfordVan 0:b9164b348919 127 int average = sum / MICROBIT_LIGHT_SENSOR_CHAN_NUM;
MrBedfordVan 0:b9164b348919 128
MrBedfordVan 0:b9164b348919 129 average = min(average, MICROBIT_LIGHT_SENSOR_MAX_VALUE);
MrBedfordVan 0:b9164b348919 130
MrBedfordVan 0:b9164b348919 131 average = max(average, MICROBIT_LIGHT_SENSOR_MIN_VALUE);
MrBedfordVan 0:b9164b348919 132
MrBedfordVan 0:b9164b348919 133 int inverted = (MICROBIT_LIGHT_SENSOR_MAX_VALUE - average) + MICROBIT_LIGHT_SENSOR_MIN_VALUE;
MrBedfordVan 0:b9164b348919 134
MrBedfordVan 0:b9164b348919 135 int a = 0;
MrBedfordVan 0:b9164b348919 136
MrBedfordVan 0:b9164b348919 137 int b = 255;
MrBedfordVan 0:b9164b348919 138
MrBedfordVan 0:b9164b348919 139 int normalised = a + ((((inverted - MICROBIT_LIGHT_SENSOR_MIN_VALUE)) * (b - a))/ (MICROBIT_LIGHT_SENSOR_MAX_VALUE - MICROBIT_LIGHT_SENSOR_MIN_VALUE));
MrBedfordVan 0:b9164b348919 140
MrBedfordVan 0:b9164b348919 141 return normalised;
MrBedfordVan 0:b9164b348919 142 }
MrBedfordVan 0:b9164b348919 143
MrBedfordVan 0:b9164b348919 144 /**
MrBedfordVan 0:b9164b348919 145 * The method that is invoked by sending MICROBIT_DISPLAY_EVT_LIGHT_SENSE
MrBedfordVan 0:b9164b348919 146 * using the id MICROBIT_ID_DISPLAY.
MrBedfordVan 0:b9164b348919 147 *
MrBedfordVan 0:b9164b348919 148 * @note this can be manually driven by calling this member function, with
MrBedfordVan 0:b9164b348919 149 * a MicroBitEvent using the CREATE_ONLY option of the MicroBitEvent
MrBedfordVan 0:b9164b348919 150 * constructor.
MrBedfordVan 0:b9164b348919 151 */
MrBedfordVan 0:b9164b348919 152 void MicroBitLightSensor::startSensing(MicroBitEvent)
MrBedfordVan 0:b9164b348919 153 {
MrBedfordVan 0:b9164b348919 154 for(int rowCount = 0; rowCount < matrixMap.rows; rowCount++)
MrBedfordVan 0:b9164b348919 155 DigitalOut((PinName)(matrixMap.rowStart + rowCount)).write(0);
MrBedfordVan 0:b9164b348919 156
MrBedfordVan 0:b9164b348919 157 PinName currentPin = (PinName)(matrixMap.columnStart + chan);
MrBedfordVan 0:b9164b348919 158
MrBedfordVan 0:b9164b348919 159 DigitalOut(currentPin).write(1);
MrBedfordVan 0:b9164b348919 160
MrBedfordVan 0:b9164b348919 161 DigitalIn(currentPin, PullNone).~DigitalIn();
MrBedfordVan 0:b9164b348919 162
MrBedfordVan 0:b9164b348919 163 if(this->sensePin != NULL)
MrBedfordVan 0:b9164b348919 164 delete this->sensePin;
MrBedfordVan 0:b9164b348919 165
MrBedfordVan 0:b9164b348919 166 this->sensePin = new AnalogIn(currentPin);
MrBedfordVan 0:b9164b348919 167
MrBedfordVan 0:b9164b348919 168 analogTrigger.attach_us(this, &MicroBitLightSensor::analogReady, MICROBIT_LIGHT_SENSOR_AN_SET_TIME);
MrBedfordVan 0:b9164b348919 169 }
MrBedfordVan 0:b9164b348919 170
MrBedfordVan 0:b9164b348919 171 /**
MrBedfordVan 0:b9164b348919 172 * A destructor for MicroBitLightSensor.
MrBedfordVan 0:b9164b348919 173 *
MrBedfordVan 0:b9164b348919 174 * The destructor removes the listener, used by MicroBitLightSensor from the default EventModel.
MrBedfordVan 0:b9164b348919 175 */
MrBedfordVan 0:b9164b348919 176 MicroBitLightSensor::~MicroBitLightSensor()
MrBedfordVan 0:b9164b348919 177 {
MrBedfordVan 0:b9164b348919 178 if (EventModel::defaultEventBus)
MrBedfordVan 0:b9164b348919 179 EventModel::defaultEventBus->ignore(MICROBIT_ID_DISPLAY, MICROBIT_DISPLAY_EVT_LIGHT_SENSE, this, &MicroBitLightSensor::startSensing);
MrBedfordVan 0:b9164b348919 180 }