Martin Cottrell / microbit-dal

No Changes

Dependencies:   BLE_API mbed-dev-bin nRF51822

Dependents:   microbit

Fork of microbit-dal by Lancaster University

source/drivers/MicroBitRadio.cpp@21:cab56b701601, 2016-07-13 (annotated)

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:17:53 2016 +0100
Revision:
21:cab56b701601
Parent:
19:ebc07f856999
Child:
22:23d7b9a4b082
Synchronized with git rev 87f7233a

Author: Martin Woolley

Added BLE connect/disconnect events and fixed bug in MagnetometerService re: bearing characteristic

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Jonathan Austin 1:8aa5cdb4ab67 1 /*
Jonathan Austin 1:8aa5cdb4ab67 2 The MIT License (MIT)
Jonathan Austin 1:8aa5cdb4ab67 3
Jonathan Austin 1:8aa5cdb4ab67 4 Copyright (c) 2016 British Broadcasting Corporation.
Jonathan Austin 1:8aa5cdb4ab67 5 This software is provided by Lancaster University by arrangement with the BBC.
Jonathan Austin 1:8aa5cdb4ab67 6
Jonathan Austin 1:8aa5cdb4ab67 7 Permission is hereby granted, free of charge, to any person obtaining a
Jonathan Austin 1:8aa5cdb4ab67 8 copy of this software and associated documentation files (the "Software"),
Jonathan Austin 1:8aa5cdb4ab67 9 to deal in the Software without restriction, including without limitation
Jonathan Austin 1:8aa5cdb4ab67 10 the rights to use, copy, modify, merge, publish, distribute, sublicense,
Jonathan Austin 1:8aa5cdb4ab67 11 and/or sell copies of the Software, and to permit persons to whom the
Jonathan Austin 1:8aa5cdb4ab67 12 Software is furnished to do so, subject to the following conditions:
Jonathan Austin 1:8aa5cdb4ab67 13
Jonathan Austin 1:8aa5cdb4ab67 14 The above copyright notice and this permission notice shall be included in
Jonathan Austin 1:8aa5cdb4ab67 15 all copies or substantial portions of the Software.
Jonathan Austin 1:8aa5cdb4ab67 16
Jonathan Austin 1:8aa5cdb4ab67 17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Jonathan Austin 1:8aa5cdb4ab67 18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Jonathan Austin 1:8aa5cdb4ab67 19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
Jonathan Austin 1:8aa5cdb4ab67 20 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Jonathan Austin 1:8aa5cdb4ab67 21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
Jonathan Austin 1:8aa5cdb4ab67 22 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
Jonathan Austin 1:8aa5cdb4ab67 23 DEALINGS IN THE SOFTWARE.
Jonathan Austin 1:8aa5cdb4ab67 24 */
Jonathan Austin 1:8aa5cdb4ab67 25
Jonathan Austin 1:8aa5cdb4ab67 26 #include "MicroBitConfig.h"
Jonathan Austin 1:8aa5cdb4ab67 27 #include "MicroBitRadio.h"
Jonathan Austin 1:8aa5cdb4ab67 28 #include "MicroBitComponent.h"
Jonathan Austin 1:8aa5cdb4ab67 29 #include "EventModel.h"
Jonathan Austin 1:8aa5cdb4ab67 30 #include "MicroBitDevice.h"
Jonathan Austin 1:8aa5cdb4ab67 31 #include "ErrorNo.h"
Jonathan Austin 1:8aa5cdb4ab67 32 #include "MicroBitFiber.h"
Jonathan Austin 1:8aa5cdb4ab67 33 #include "MicroBitBLEManager.h"
Jonathan Austin 1:8aa5cdb4ab67 34
Jonathan Austin 1:8aa5cdb4ab67 35 /**
Jonathan Austin 1:8aa5cdb4ab67 36 * Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
Jonathan Austin 1:8aa5cdb4ab67 37 *
Jonathan Austin 1:8aa5cdb4ab67 38 * The nrf51822 RADIO module supports a number of proprietary modes of operation oher than the typical BLE usage.
Jonathan Austin 1:8aa5cdb4ab67 39 * This class uses one of these modes to enable simple, point to multipoint communication directly between micro:bits.
Jonathan Austin 1:8aa5cdb4ab67 40 *
Jonathan Austin 1:8aa5cdb4ab67 41 * TODO: The protocols implemented here do not currently perform any significant form of energy management,
Jonathan Austin 1:8aa5cdb4ab67 42 * which means that they will consume far more energy than their BLE equivalent. Later versions of the protocol
Jonathan Austin 1:8aa5cdb4ab67 43 * should look to address this through energy efficient broadcast techbiques / sleep scheduling. In particular, the GLOSSY
Jonathan Austin 1:8aa5cdb4ab67 44 * approach to efficient rebroadcast and network synchronisation would likely provide an effective future step.
Jonathan Austin 1:8aa5cdb4ab67 45 *
Jonathan Austin 1:8aa5cdb4ab67 46 * TODO: Meshing should also be considered - again a GLOSSY approach may be effective here, and highly complementary to
Jonathan Austin 1:8aa5cdb4ab67 47 * the master/slave arachitecture of BLE.
Jonathan Austin 1:8aa5cdb4ab67 48 *
Jonathan Austin 1:8aa5cdb4ab67 49 * TODO: This implementation may only operated whilst the BLE stack is disabled. The nrf51822 provides a timeslot API to allow
Jonathan Austin 1:8aa5cdb4ab67 50 * BLE to cohabit with other protocols. Future work to allow this colocation would be benefical, and would also allow for the
Jonathan Austin 1:8aa5cdb4ab67 51 * creation of wireless BLE bridges.
Jonathan Austin 1:8aa5cdb4ab67 52 *
Jonathan Austin 1:8aa5cdb4ab67 53 * NOTE: This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a
Jonathan Austin 1:8aa5cdb4ab67 54 * teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
Jonathan Austin 1:8aa5cdb4ab67 55 * For serious applications, BLE should be considered a substantially more secure alternative.
Jonathan Austin 1:8aa5cdb4ab67 56 */
Jonathan Austin 1:8aa5cdb4ab67 57
Jonathan Austin 1:8aa5cdb4ab67 58 MicroBitRadio* MicroBitRadio::instance = NULL;
Jonathan Austin 1:8aa5cdb4ab67 59
Jonathan Austin 1:8aa5cdb4ab67 60 extern "C" void RADIO_IRQHandler(void)
Jonathan Austin 1:8aa5cdb4ab67 61 {
Jonathan Austin 1:8aa5cdb4ab67 62 // Move on to the next buffer, if possible.
Jonathan Austin 1:8aa5cdb4ab67 63 MicroBitRadio::instance->queueRxBuf();
Jonathan Austin 1:8aa5cdb4ab67 64 NRF_RADIO->PACKETPTR = (uint32_t) MicroBitRadio::instance->getRxBuf();
Jonathan Austin 1:8aa5cdb4ab67 65
Jonathan Austin 1:8aa5cdb4ab67 66 if(NRF_RADIO->EVENTS_READY)
Jonathan Austin 1:8aa5cdb4ab67 67 {
Jonathan Austin 1:8aa5cdb4ab67 68 NRF_RADIO->EVENTS_READY = 0;
Jonathan Austin 1:8aa5cdb4ab67 69
Jonathan Austin 1:8aa5cdb4ab67 70 // Start listening and wait for the END event
Jonathan Austin 1:8aa5cdb4ab67 71 NRF_RADIO->TASKS_START = 1;
Jonathan Austin 1:8aa5cdb4ab67 72 }
Jonathan Austin 1:8aa5cdb4ab67 73
Jonathan Austin 1:8aa5cdb4ab67 74 if(NRF_RADIO->EVENTS_END)
Jonathan Austin 1:8aa5cdb4ab67 75 {
Jonathan Austin 1:8aa5cdb4ab67 76 NRF_RADIO->EVENTS_END = 0;
Jonathan Austin 1:8aa5cdb4ab67 77
Jonathan Austin 1:8aa5cdb4ab67 78 if(NRF_RADIO->CRCSTATUS == 1)
Jonathan Austin 1:8aa5cdb4ab67 79 {
Jonathan Austin 1:8aa5cdb4ab67 80 uint8_t sample = NRF_RADIO->RSSISAMPLE;
Jonathan Austin 1:8aa5cdb4ab67 81
Jonathan Austin 1:8aa5cdb4ab67 82 MicroBitRadio::instance->setRSSI(sample);
Jonathan Austin 1:8aa5cdb4ab67 83 }
Jonathan Austin 1:8aa5cdb4ab67 84
Jonathan Austin 1:8aa5cdb4ab67 85 // Start listening and wait for the END event
Jonathan Austin 1:8aa5cdb4ab67 86 NRF_RADIO->TASKS_START = 1;
Jonathan Austin 1:8aa5cdb4ab67 87 }
Jonathan Austin 1:8aa5cdb4ab67 88 }
Jonathan Austin 1:8aa5cdb4ab67 89
Jonathan Austin 1:8aa5cdb4ab67 90 /**
Jonathan Austin 1:8aa5cdb4ab67 91 * Constructor.
Jonathan Austin 1:8aa5cdb4ab67 92 *
Jonathan Austin 1:8aa5cdb4ab67 93 * Initialise the MicroBitRadio.
Jonathan Austin 1:8aa5cdb4ab67 94 *
Jonathan Austin 1:8aa5cdb4ab67 95 * @note This class is demand activated, as a result most resources are only
Jonathan Austin 1:8aa5cdb4ab67 96 * committed if send/recv or event registrations calls are made.
Jonathan Austin 1:8aa5cdb4ab67 97 */
Jonathan Austin 1:8aa5cdb4ab67 98 MicroBitRadio::MicroBitRadio(uint16_t id) : datagram(*this), event (*this)
Jonathan Austin 1:8aa5cdb4ab67 99 {
Jonathan Austin 1:8aa5cdb4ab67 100 this->id = id;
Jonathan Austin 1:8aa5cdb4ab67 101 this->status = 0;
LancasterUniversity 21:cab56b701601 102 this->group = 0;
Jonathan Austin 1:8aa5cdb4ab67 103 this->queueDepth = 0;
Jonathan Austin 1:8aa5cdb4ab67 104 this->rssi = 0;
Jonathan Austin 1:8aa5cdb4ab67 105 this->rxQueue = NULL;
Jonathan Austin 1:8aa5cdb4ab67 106 this->rxBuf = NULL;
Jonathan Austin 1:8aa5cdb4ab67 107
Jonathan Austin 1:8aa5cdb4ab67 108 instance = this;
Jonathan Austin 1:8aa5cdb4ab67 109 }
Jonathan Austin 1:8aa5cdb4ab67 110
Jonathan Austin 1:8aa5cdb4ab67 111 /**
Jonathan Austin 1:8aa5cdb4ab67 112 * Change the output power level of the transmitter to the given value.
Jonathan Austin 1:8aa5cdb4ab67 113 *
Jonathan Austin 1:8aa5cdb4ab67 114 * @param power a value in the range 0..7, where 0 is the lowest power and 7 is the highest.
Jonathan Austin 1:8aa5cdb4ab67 115 *
Jonathan Austin 1:8aa5cdb4ab67 116 * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the value is out of range.
Jonathan Austin 1:8aa5cdb4ab67 117 */
Jonathan Austin 1:8aa5cdb4ab67 118 int MicroBitRadio::setTransmitPower(int power)
Jonathan Austin 1:8aa5cdb4ab67 119 {
Jonathan Austin 1:8aa5cdb4ab67 120 if (power < 0 || power >= MICROBIT_BLE_POWER_LEVELS)
Jonathan Austin 1:8aa5cdb4ab67 121 return MICROBIT_INVALID_PARAMETER;
Jonathan Austin 1:8aa5cdb4ab67 122
Jonathan Austin 1:8aa5cdb4ab67 123 NRF_RADIO->TXPOWER = (uint32_t)MICROBIT_BLE_POWER_LEVEL[power];
Jonathan Austin 1:8aa5cdb4ab67 124
Jonathan Austin 1:8aa5cdb4ab67 125 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 126 }
Jonathan Austin 1:8aa5cdb4ab67 127
Jonathan Austin 1:8aa5cdb4ab67 128 /**
Jonathan Austin 1:8aa5cdb4ab67 129 * Change the transmission and reception band of the radio to the given channel
Jonathan Austin 1:8aa5cdb4ab67 130 *
Jonathan Austin 1:8aa5cdb4ab67 131 * @param band a frequency band in the range 0 - 100. Each step is 1MHz wide, based at 2400MHz.
Jonathan Austin 1:8aa5cdb4ab67 132 *
Jonathan Austin 1:8aa5cdb4ab67 133 * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the value is out of range,
Jonathan Austin 1:8aa5cdb4ab67 134 * or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
Jonathan Austin 1:8aa5cdb4ab67 135 */
Jonathan Austin 1:8aa5cdb4ab67 136 int MicroBitRadio::setFrequencyBand(int band)
Jonathan Austin 1:8aa5cdb4ab67 137 {
Jonathan Austin 1:8aa5cdb4ab67 138 if (ble_running())
Jonathan Austin 1:8aa5cdb4ab67 139 return MICROBIT_NOT_SUPPORTED;
Jonathan Austin 1:8aa5cdb4ab67 140
Jonathan Austin 1:8aa5cdb4ab67 141 if (band < 0 || band > 100)
Jonathan Austin 1:8aa5cdb4ab67 142 return MICROBIT_INVALID_PARAMETER;
Jonathan Austin 1:8aa5cdb4ab67 143
Jonathan Austin 1:8aa5cdb4ab67 144 NRF_RADIO->FREQUENCY = (uint32_t)band;
Jonathan Austin 1:8aa5cdb4ab67 145
Jonathan Austin 1:8aa5cdb4ab67 146 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 147 }
Jonathan Austin 1:8aa5cdb4ab67 148
Jonathan Austin 1:8aa5cdb4ab67 149 /**
Jonathan Austin 1:8aa5cdb4ab67 150 * Retrieve a pointer to the currently allocated receive buffer. This is the area of memory
Jonathan Austin 1:8aa5cdb4ab67 151 * actively being used by the radio hardware to store incoming data.
Jonathan Austin 1:8aa5cdb4ab67 152 *
Jonathan Austin 1:8aa5cdb4ab67 153 * @return a pointer to the current receive buffer.
Jonathan Austin 1:8aa5cdb4ab67 154 */
Jonathan Austin 1:8aa5cdb4ab67 155 FrameBuffer* MicroBitRadio::getRxBuf()
Jonathan Austin 1:8aa5cdb4ab67 156 {
Jonathan Austin 1:8aa5cdb4ab67 157 return rxBuf;
Jonathan Austin 1:8aa5cdb4ab67 158 }
Jonathan Austin 1:8aa5cdb4ab67 159
Jonathan Austin 1:8aa5cdb4ab67 160 /**
Jonathan Austin 1:8aa5cdb4ab67 161 * Attempt to queue a buffer received by the radio hardware, if sufficient space is available.
Jonathan Austin 1:8aa5cdb4ab67 162 *
Jonathan Austin 1:8aa5cdb4ab67 163 * @return MICROBIT_OK on success, or MICROBIT_NO_RESOURCES if a replacement receiver buffer
Jonathan Austin 1:8aa5cdb4ab67 164 * could not be allocated (either by policy or memory exhaustion).
Jonathan Austin 1:8aa5cdb4ab67 165 */
Jonathan Austin 1:8aa5cdb4ab67 166 int MicroBitRadio::queueRxBuf()
Jonathan Austin 1:8aa5cdb4ab67 167 {
Jonathan Austin 1:8aa5cdb4ab67 168 if (rxBuf == NULL)
Jonathan Austin 1:8aa5cdb4ab67 169 return MICROBIT_INVALID_PARAMETER;
Jonathan Austin 1:8aa5cdb4ab67 170
Jonathan Austin 1:8aa5cdb4ab67 171 if (queueDepth >= MICROBIT_RADIO_MAXIMUM_RX_BUFFERS)
Jonathan Austin 1:8aa5cdb4ab67 172 return MICROBIT_NO_RESOURCES;
Jonathan Austin 1:8aa5cdb4ab67 173
Jonathan Austin 1:8aa5cdb4ab67 174 // Store the received RSSI value in the frame
Jonathan Austin 1:8aa5cdb4ab67 175 rxBuf->rssi = getRSSI();
Jonathan Austin 1:8aa5cdb4ab67 176
Jonathan Austin 1:8aa5cdb4ab67 177 // Ensure that a replacement buffer is available before queuing.
Jonathan Austin 1:8aa5cdb4ab67 178 FrameBuffer *newRxBuf = new FrameBuffer();
Jonathan Austin 1:8aa5cdb4ab67 179
Jonathan Austin 1:8aa5cdb4ab67 180 if (newRxBuf == NULL)
Jonathan Austin 1:8aa5cdb4ab67 181 return MICROBIT_NO_RESOURCES;
Jonathan Austin 1:8aa5cdb4ab67 182
Jonathan Austin 1:8aa5cdb4ab67 183 // We add to the tail of the queue to preserve causal ordering.
Jonathan Austin 1:8aa5cdb4ab67 184 rxBuf->next = NULL;
Jonathan Austin 1:8aa5cdb4ab67 185
Jonathan Austin 1:8aa5cdb4ab67 186 if (rxQueue == NULL)
Jonathan Austin 1:8aa5cdb4ab67 187 {
Jonathan Austin 1:8aa5cdb4ab67 188 rxQueue = rxBuf;
Jonathan Austin 1:8aa5cdb4ab67 189 }
Jonathan Austin 1:8aa5cdb4ab67 190 else
Jonathan Austin 1:8aa5cdb4ab67 191 {
Jonathan Austin 1:8aa5cdb4ab67 192 FrameBuffer *p = rxQueue;
Jonathan Austin 1:8aa5cdb4ab67 193 while (p->next != NULL)
Jonathan Austin 1:8aa5cdb4ab67 194 p = p->next;
Jonathan Austin 1:8aa5cdb4ab67 195
Jonathan Austin 1:8aa5cdb4ab67 196 p->next = rxBuf;
Jonathan Austin 1:8aa5cdb4ab67 197 }
Jonathan Austin 1:8aa5cdb4ab67 198
Jonathan Austin 1:8aa5cdb4ab67 199 // Increase our received packet count
Jonathan Austin 1:8aa5cdb4ab67 200 queueDepth++;
Jonathan Austin 1:8aa5cdb4ab67 201
Jonathan Austin 1:8aa5cdb4ab67 202 // Allocate a new buffer for the receiver hardware to use. the old on will be passed on to higher layer protocols/apps.
Jonathan Austin 1:8aa5cdb4ab67 203 rxBuf = newRxBuf;
Jonathan Austin 1:8aa5cdb4ab67 204
Jonathan Austin 1:8aa5cdb4ab67 205 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 206 }
Jonathan Austin 1:8aa5cdb4ab67 207
Jonathan Austin 1:8aa5cdb4ab67 208 /**
Jonathan Austin 1:8aa5cdb4ab67 209 * Sets the RSSI for the most recent packet.
Jonathan Austin 1:8aa5cdb4ab67 210 *
Jonathan Austin 1:8aa5cdb4ab67 211 * @param rssi the new rssi value.
Jonathan Austin 1:8aa5cdb4ab67 212 *
Jonathan Austin 1:8aa5cdb4ab67 213 * @note should only be called from RADIO_IRQHandler...
Jonathan Austin 1:8aa5cdb4ab67 214 */
Jonathan Austin 1:8aa5cdb4ab67 215 int MicroBitRadio::setRSSI(uint8_t rssi)
Jonathan Austin 1:8aa5cdb4ab67 216 {
Jonathan Austin 1:8aa5cdb4ab67 217 if (!(status & MICROBIT_RADIO_STATUS_INITIALISED))
Jonathan Austin 1:8aa5cdb4ab67 218 return MICROBIT_NOT_SUPPORTED;
Jonathan Austin 1:8aa5cdb4ab67 219
Jonathan Austin 1:8aa5cdb4ab67 220 this->rssi = rssi;
Jonathan Austin 1:8aa5cdb4ab67 221
Jonathan Austin 1:8aa5cdb4ab67 222 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 223 }
Jonathan Austin 1:8aa5cdb4ab67 224
Jonathan Austin 1:8aa5cdb4ab67 225 /**
Jonathan Austin 1:8aa5cdb4ab67 226 * Retrieves the current RSSI for the most recent packet.
Jonathan Austin 1:8aa5cdb4ab67 227 *
Jonathan Austin 1:8aa5cdb4ab67 228 * @return the most recent RSSI value or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
Jonathan Austin 1:8aa5cdb4ab67 229 */
Jonathan Austin 1:8aa5cdb4ab67 230 int MicroBitRadio::getRSSI()
Jonathan Austin 1:8aa5cdb4ab67 231 {
Jonathan Austin 1:8aa5cdb4ab67 232 if (!(status & MICROBIT_RADIO_STATUS_INITIALISED))
Jonathan Austin 1:8aa5cdb4ab67 233 return MICROBIT_NOT_SUPPORTED;
Jonathan Austin 1:8aa5cdb4ab67 234
Jonathan Austin 1:8aa5cdb4ab67 235 return this->rssi;
Jonathan Austin 1:8aa5cdb4ab67 236 }
Jonathan Austin 1:8aa5cdb4ab67 237
Jonathan Austin 1:8aa5cdb4ab67 238 /**
Jonathan Austin 1:8aa5cdb4ab67 239 * Initialises the radio for use as a multipoint sender/receiver
Jonathan Austin 1:8aa5cdb4ab67 240 *
Jonathan Austin 1:8aa5cdb4ab67 241 * @return MICROBIT_OK on success, MICROBIT_NOT_SUPPORTED if the BLE stack is running.
Jonathan Austin 1:8aa5cdb4ab67 242 */
Jonathan Austin 1:8aa5cdb4ab67 243 int MicroBitRadio::enable()
Jonathan Austin 1:8aa5cdb4ab67 244 {
Jonathan Austin 1:8aa5cdb4ab67 245 // If the device is already initialised, then there's nothing to do.
Jonathan Austin 1:8aa5cdb4ab67 246 if (status & MICROBIT_RADIO_STATUS_INITIALISED)
Jonathan Austin 1:8aa5cdb4ab67 247 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 248
Jonathan Austin 1:8aa5cdb4ab67 249 // Only attempt to enable this radio mode if BLE is disabled.
Jonathan Austin 1:8aa5cdb4ab67 250 if (ble_running())
Jonathan Austin 1:8aa5cdb4ab67 251 return MICROBIT_NOT_SUPPORTED;
Jonathan Austin 1:8aa5cdb4ab67 252
Jonathan Austin 1:8aa5cdb4ab67 253 // If this is the first time we've been enable, allocate out receive buffers.
Jonathan Austin 1:8aa5cdb4ab67 254 if (rxBuf == NULL)
Jonathan Austin 1:8aa5cdb4ab67 255 rxBuf = new FrameBuffer();
Jonathan Austin 1:8aa5cdb4ab67 256
Jonathan Austin 1:8aa5cdb4ab67 257 if (rxBuf == NULL)
Jonathan Austin 1:8aa5cdb4ab67 258 return MICROBIT_NO_RESOURCES;
Jonathan Austin 1:8aa5cdb4ab67 259
Jonathan Austin 1:8aa5cdb4ab67 260 // Enable the High Frequency clock on the processor. This is a pre-requisite for
Jonathan Austin 1:8aa5cdb4ab67 261 // the RADIO module. Without this clock, no communication is possible.
Jonathan Austin 1:8aa5cdb4ab67 262 NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
Jonathan Austin 1:8aa5cdb4ab67 263 NRF_CLOCK->TASKS_HFCLKSTART = 1;
Jonathan Austin 1:8aa5cdb4ab67 264 while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
Jonathan Austin 1:8aa5cdb4ab67 265
Jonathan Austin 1:8aa5cdb4ab67 266 // Bring up the nrf51822 RADIO module in Nordic's proprietary 1MBps packet radio mode.
Jonathan Austin 1:8aa5cdb4ab67 267 setTransmitPower(MICROBIT_RADIO_DEFAULT_TX_POWER);
Jonathan Austin 1:8aa5cdb4ab67 268 setFrequencyBand(MICROBIT_RADIO_DEFAULT_FREQUENCY);
Jonathan Austin 1:8aa5cdb4ab67 269
Jonathan Austin 1:8aa5cdb4ab67 270 // Configure for 1Mbps throughput.
Jonathan Austin 1:8aa5cdb4ab67 271 // This may sound excessive, but running a high data rates reduces the chances of collisions...
Jonathan Austin 1:8aa5cdb4ab67 272 NRF_RADIO->MODE = RADIO_MODE_MODE_Nrf_1Mbit;
Jonathan Austin 1:8aa5cdb4ab67 273
Jonathan Austin 1:8aa5cdb4ab67 274 // Configure the addresses we use for this protocol. We run ANONYMOUSLY at the core.
Jonathan Austin 1:8aa5cdb4ab67 275 // A 40 bit addresses is used. The first 32 bits match the ASCII character code for "uBit".
Jonathan Austin 1:8aa5cdb4ab67 276 // Statistically, this provides assurance to avoid other similar 2.4GHz protocols that may be in the vicinity.
Jonathan Austin 1:8aa5cdb4ab67 277 // We also map the assigned 8-bit GROUP id into the PREFIX field. This allows the RADIO hardware to perform
Jonathan Austin 1:8aa5cdb4ab67 278 // address matching for us, and only generate an interrupt when a packet matching our group is received.
Jonathan Austin 1:8aa5cdb4ab67 279 NRF_RADIO->BASE0 = MICROBIT_RADIO_BASE_ADDRESS;
Jonathan Austin 1:8aa5cdb4ab67 280
Jonathan Austin 1:8aa5cdb4ab67 281 // Join the default group. This will configure the remaining byte in the RADIO hardware module.
LancasterUniversity 21:cab56b701601 282 setGroup(MICROBIT_RADIO_DEFAULT_GROUP);
Jonathan Austin 1:8aa5cdb4ab67 283
Jonathan Austin 1:8aa5cdb4ab67 284 // The RADIO hardware module supports the use of multiple addresses, but as we're running anonymously, we only need one.
Jonathan Austin 1:8aa5cdb4ab67 285 // Configure the RADIO module to use the default address (address 0) for both send and receive operations.
Jonathan Austin 1:8aa5cdb4ab67 286 NRF_RADIO->TXADDRESS = 0;
Jonathan Austin 1:8aa5cdb4ab67 287 NRF_RADIO->RXADDRESSES = 1;
Jonathan Austin 1:8aa5cdb4ab67 288
Jonathan Austin 1:8aa5cdb4ab67 289 // Packet layout configuration. The nrf51822 has a highly capable and flexible RADIO module that, in addition to transmission
Jonathan Austin 1:8aa5cdb4ab67 290 // and reception of data, also contains a LENGTH field, two optional additional 1 byte fields (S0 and S1) and a CRC calculation.
Jonathan Austin 1:8aa5cdb4ab67 291 // Configure the packet format for a simple 8 bit length field and no additional fields.
Jonathan Austin 1:8aa5cdb4ab67 292 NRF_RADIO->PCNF0 = 0x00000008;
Jonathan Austin 1:8aa5cdb4ab67 293 NRF_RADIO->PCNF1 = 0x02040000 | MICROBIT_RADIO_MAX_PACKET_SIZE;
Jonathan Austin 1:8aa5cdb4ab67 294
Jonathan Austin 1:8aa5cdb4ab67 295 // Most communication channels contain some form of checksum - a mathematical calculation taken based on all the data
Jonathan Austin 1:8aa5cdb4ab67 296 // in a packet, that is also sent as part of the packet. When received, this calculation can be repeated, and the results
Jonathan Austin 1:8aa5cdb4ab67 297 // from the sender and receiver compared. If they are different, then some corruption of the data ahas happened in transit,
Jonathan Austin 1:8aa5cdb4ab67 298 // and we know we can't trust it. The nrf51822 RADIO uses a CRC for this - a very effective checksum calculation.
Jonathan Austin 1:8aa5cdb4ab67 299 //
Jonathan Austin 1:8aa5cdb4ab67 300 // Enable automatic 16bit CRC generation and checking, and configure how the CRC is calculated.
Jonathan Austin 1:8aa5cdb4ab67 301 NRF_RADIO->CRCCNF = RADIO_CRCCNF_LEN_Two;
Jonathan Austin 1:8aa5cdb4ab67 302 NRF_RADIO->CRCINIT = 0xFFFF;
Jonathan Austin 1:8aa5cdb4ab67 303 NRF_RADIO->CRCPOLY = 0x11021;
Jonathan Austin 1:8aa5cdb4ab67 304
Jonathan Austin 1:8aa5cdb4ab67 305 // Set the start random value of the data whitening algorithm. This can be any non zero number.
Jonathan Austin 1:8aa5cdb4ab67 306 NRF_RADIO->DATAWHITEIV = 0x18;
Jonathan Austin 1:8aa5cdb4ab67 307
Jonathan Austin 1:8aa5cdb4ab67 308 // Set up the RADIO module to read and write from our internal buffer.
Jonathan Austin 1:8aa5cdb4ab67 309 NRF_RADIO->PACKETPTR = (uint32_t)rxBuf;
Jonathan Austin 1:8aa5cdb4ab67 310
Jonathan Austin 1:8aa5cdb4ab67 311 // Configure the hardware to issue an interrupt whenever a task is complete (e.g. send/receive).
Jonathan Austin 1:8aa5cdb4ab67 312 NRF_RADIO->INTENSET = 0x00000008;
Jonathan Austin 1:8aa5cdb4ab67 313 NVIC_ClearPendingIRQ(RADIO_IRQn);
Jonathan Austin 1:8aa5cdb4ab67 314 NVIC_EnableIRQ(RADIO_IRQn);
Jonathan Austin 1:8aa5cdb4ab67 315
Jonathan Austin 1:8aa5cdb4ab67 316 NRF_RADIO->SHORTS |= RADIO_SHORTS_ADDRESS_RSSISTART_Msk;
Jonathan Austin 1:8aa5cdb4ab67 317
Jonathan Austin 1:8aa5cdb4ab67 318 // Start listening for the next packet
Jonathan Austin 1:8aa5cdb4ab67 319 NRF_RADIO->EVENTS_READY = 0;
Jonathan Austin 1:8aa5cdb4ab67 320 NRF_RADIO->TASKS_RXEN = 1;
Jonathan Austin 1:8aa5cdb4ab67 321 while(NRF_RADIO->EVENTS_READY == 0);
Jonathan Austin 1:8aa5cdb4ab67 322
Jonathan Austin 1:8aa5cdb4ab67 323 NRF_RADIO->EVENTS_END = 0;
Jonathan Austin 1:8aa5cdb4ab67 324 NRF_RADIO->TASKS_START = 1;
Jonathan Austin 1:8aa5cdb4ab67 325
Jonathan Austin 1:8aa5cdb4ab67 326 // register ourselves for a callback event, in order to empty the receive queue.
Jonathan Austin 1:8aa5cdb4ab67 327 fiber_add_idle_component(this);
Jonathan Austin 1:8aa5cdb4ab67 328
Jonathan Austin 1:8aa5cdb4ab67 329 // Done. Record that our RADIO is configured.
Jonathan Austin 1:8aa5cdb4ab67 330 status |= MICROBIT_RADIO_STATUS_INITIALISED;
Jonathan Austin 1:8aa5cdb4ab67 331
Jonathan Austin 1:8aa5cdb4ab67 332 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 333 }
Jonathan Austin 1:8aa5cdb4ab67 334
Jonathan Austin 1:8aa5cdb4ab67 335 /**
Jonathan Austin 1:8aa5cdb4ab67 336 * Disables the radio for use as a multipoint sender/receiver.
Jonathan Austin 1:8aa5cdb4ab67 337 *
Jonathan Austin 1:8aa5cdb4ab67 338 * @return MICROBIT_OK on success, MICROBIT_NOT_SUPPORTED if the BLE stack is running.
Jonathan Austin 1:8aa5cdb4ab67 339 */
Jonathan Austin 1:8aa5cdb4ab67 340 int MicroBitRadio::disable()
Jonathan Austin 1:8aa5cdb4ab67 341 {
Jonathan Austin 1:8aa5cdb4ab67 342 // Only attempt to enable.disable the radio if the protocol is alreayd running.
Jonathan Austin 1:8aa5cdb4ab67 343 if (ble_running())
Jonathan Austin 1:8aa5cdb4ab67 344 return MICROBIT_NOT_SUPPORTED;
Jonathan Austin 1:8aa5cdb4ab67 345
Jonathan Austin 1:8aa5cdb4ab67 346 if (!(status & MICROBIT_RADIO_STATUS_INITIALISED))
Jonathan Austin 1:8aa5cdb4ab67 347 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 348
Jonathan Austin 1:8aa5cdb4ab67 349 // Disable interrupts and STOP any ongoing packet reception.
Jonathan Austin 1:8aa5cdb4ab67 350 NVIC_DisableIRQ(RADIO_IRQn);
Jonathan Austin 1:8aa5cdb4ab67 351
Jonathan Austin 1:8aa5cdb4ab67 352 NRF_RADIO->EVENTS_DISABLED = 0;
Jonathan Austin 1:8aa5cdb4ab67 353 NRF_RADIO->TASKS_DISABLE = 1;
Jonathan Austin 1:8aa5cdb4ab67 354 while(NRF_RADIO->EVENTS_DISABLED == 0);
Jonathan Austin 1:8aa5cdb4ab67 355
Jonathan Austin 1:8aa5cdb4ab67 356 // deregister ourselves from the callback event used to empty the receive queue.
Jonathan Austin 1:8aa5cdb4ab67 357 fiber_remove_idle_component(this);
Jonathan Austin 1:8aa5cdb4ab67 358
Jonathan Austin 1:8aa5cdb4ab67 359 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 360 }
Jonathan Austin 1:8aa5cdb4ab67 361
Jonathan Austin 1:8aa5cdb4ab67 362 /**
Jonathan Austin 1:8aa5cdb4ab67 363 * Sets the radio to listen to packets sent with the given group id.
Jonathan Austin 1:8aa5cdb4ab67 364 *
Jonathan Austin 1:8aa5cdb4ab67 365 * @param group The group to join. A micro:bit can only listen to one group ID at any time.
Jonathan Austin 1:8aa5cdb4ab67 366 *
Jonathan Austin 1:8aa5cdb4ab67 367 * @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
Jonathan Austin 1:8aa5cdb4ab67 368 */
Jonathan Austin 1:8aa5cdb4ab67 369 int MicroBitRadio::setGroup(uint8_t group)
Jonathan Austin 1:8aa5cdb4ab67 370 {
Jonathan Austin 1:8aa5cdb4ab67 371 if (ble_running())
Jonathan Austin 1:8aa5cdb4ab67 372 return MICROBIT_NOT_SUPPORTED;
Jonathan Austin 1:8aa5cdb4ab67 373
Jonathan Austin 1:8aa5cdb4ab67 374 // Record our group id locally
Jonathan Austin 1:8aa5cdb4ab67 375 this->group = group;
Jonathan Austin 1:8aa5cdb4ab67 376
Jonathan Austin 1:8aa5cdb4ab67 377 // Also append it to the address of this device, to allow the RADIO module to filter for us.
Jonathan Austin 1:8aa5cdb4ab67 378 NRF_RADIO->PREFIX0 = (uint32_t)group;
Jonathan Austin 1:8aa5cdb4ab67 379
Jonathan Austin 1:8aa5cdb4ab67 380 return MICROBIT_OK;
Jonathan Austin 1:8aa5cdb4ab67 381 }
Jonathan Austin 1:8aa5cdb4ab67 382
Jonathan Austin 1:8aa5cdb4ab67 383 /**
Jonathan Austin 1:8aa5cdb4ab67 384 * A background, low priority callback that is triggered whenever the processor is idle.
Jonathan Austin 1:8aa5cdb4ab67 385 * Here, we empty our queue of received packets, and pass them onto higher level protocol handlers.
Jonathan Austin 1:8aa5cdb4ab67 386 */
Jonathan Austin 1:8aa5cdb4ab67 387 void MicroBitRadio::idleTick()
Jonathan Austin 1:8aa5cdb4ab67 388 {
Jonathan Austin 1:8aa5cdb4ab67 389 // Walk the list of packets and process each one.
Jonathan Austin 1:8aa5cdb4ab67 390 while(rxQueue)
Jonathan Austin 1:8aa5cdb4ab67 391 {
Jonathan Austin 1:8aa5cdb4ab67 392 FrameBuffer *p = rxQueue;
Jonathan Austin 1:8aa5cdb4ab67 393
Jonathan Austin 1:8aa5cdb4ab67 394 switch (p->protocol)
Jonathan Austin 1:8aa5cdb4ab67 395 {
Jonathan Austin 1:8aa5cdb4ab67 396 case MICROBIT_RADIO_PROTOCOL_DATAGRAM:
Jonathan Austin 1:8aa5cdb4ab67 397 datagram.packetReceived();
Jonathan Austin 1:8aa5cdb4ab67 398 break;
Jonathan Austin 1:8aa5cdb4ab67 399
Jonathan Austin 1:8aa5cdb4ab67 400 case MICROBIT_RADIO_PROTOCOL_EVENTBUS:
Jonathan Austin 1:8aa5cdb4ab67 401 event.packetReceived();
Jonathan Austin 1:8aa5cdb4ab67 402 break;
Jonathan Austin 1:8aa5cdb4ab67 403
Jonathan Austin 1:8aa5cdb4ab67 404 default:
Jonathan Austin 1:8aa5cdb4ab67 405 MicroBitEvent(MICROBIT_ID_RADIO_DATA_READY, p->protocol);
Jonathan Austin 1:8aa5cdb4ab67 406 }
Jonathan Austin 1:8aa5cdb4ab67 407
Jonathan Austin 1:8aa5cdb4ab67 408 // If the packet was processed, it will have been recv'd, and taken from the queue.
Jonathan Austin 1:8aa5cdb4ab67 409 // If this was a packet for an unknown protocol, it will still be there, so simply free it.
Jonathan Austin 1:8aa5cdb4ab67 410 if (p == rxQueue)
Jonathan Austin 1:8aa5cdb4ab67 411 {
Jonathan Austin 1:8aa5cdb4ab67 412 recv();
Jonathan Austin 1:8aa5cdb4ab67 413 delete p;
Jonathan Austin 1:8aa5cdb4ab67 414 }
Jonathan Austin 1:8aa5cdb4ab67 415 }
Jonathan Austin 1:8aa5cdb4ab67 416 }
Jonathan Austin 1:8aa5cdb4ab67 417
Jonathan Austin 1:8aa5cdb4ab67 418 /**
Jonathan Austin 1:8aa5cdb4ab67 419 * Determines the number of packets ready to be processed.
Jonathan Austin 1:8aa5cdb4ab67 420 *
Jonathan Austin 1:8aa5cdb4ab67 421 * @return The number of packets in the receive buffer.
Jonathan Austin 1:8aa5cdb4ab67 422 */
Jonathan Austin 1:8aa5cdb4ab67 423 int MicroBitRadio::dataReady()
Jonathan Austin 1:8aa5cdb4ab67 424 {
Jonathan Austin 1:8aa5cdb4ab67 425 return queueDepth;
Jonathan Austin 1:8aa5cdb4ab67 426 }
Jonathan Austin 1:8aa5cdb4ab67 427
Jonathan Austin 1:8aa5cdb4ab67 428 /**
Jonathan Austin 1:8aa5cdb4ab67 429 * Retrieves the next packet from the receive buffer.
Jonathan Austin 1:8aa5cdb4ab67 430 * If a data packet is available, then it will be returned immediately to
Jonathan Austin 1:8aa5cdb4ab67 431 * the caller. This call will also dequeue the buffer.
Jonathan Austin 1:8aa5cdb4ab67 432 *
Jonathan Austin 1:8aa5cdb4ab67 433 * @return The buffer containing the the packet. If no data is available, NULL is returned.
Jonathan Austin 1:8aa5cdb4ab67 434 *
Jonathan Austin 1:8aa5cdb4ab67 435 * @note Once recv() has been called, it is the callers resposibility to
Jonathan Austin 1:8aa5cdb4ab67 436 * delete the buffer when appropriate.
Jonathan Austin 1:8aa5cdb4ab67 437 */
Jonathan Austin 1:8aa5cdb4ab67 438 FrameBuffer* MicroBitRadio::recv()
Jonathan Austin 1:8aa5cdb4ab67 439 {
Jonathan Austin 1:8aa5cdb4ab67 440 FrameBuffer *p = rxQueue;
Jonathan Austin 1:8aa5cdb4ab67 441
Jonathan Austin 1:8aa5cdb4ab67 442 if (p)
Jonathan Austin 1:8aa5cdb4ab67 443 {
Jonathan Austin 1:8aa5cdb4ab67 444 rxQueue = rxQueue->next;
Jonathan Austin 1:8aa5cdb4ab67 445 queueDepth--;
Jonathan Austin 1:8aa5cdb4ab67 446 }
Jonathan Austin 1:8aa5cdb4ab67 447
Jonathan Austin 1:8aa5cdb4ab67 448 return p;
Jonathan Austin 1:8aa5cdb4ab67 449 }
Jonathan Austin 1:8aa5cdb4ab67 450
Jonathan Austin 1:8aa5cdb4ab67 451 /**
Jonathan Austin 1:8aa5cdb4ab67 452 * Transmits the given buffer onto the broadcast radio.
Jonathan Austin 1:8aa5cdb4ab67 453 * The call will wait until the transmission of the packet has completed before returning.
Jonathan Austin 1:8aa5cdb4ab67 454 *
Jonathan Austin 1:8aa5cdb4ab67 455 * @param data The packet contents to transmit.
Jonathan Austin 1:8aa5cdb4ab67 456 *
Jonathan Austin 1:8aa5cdb4ab67 457 * @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
Jonathan Austin 1:8aa5cdb4ab67 458 */
Jonathan Austin 1:8aa5cdb4ab67 459 int MicroBitRadio::send(FrameBuffer *buffer)
Jonathan Austin 1:8aa5cdb4ab67 460 {
Jonathan Austin 1:8aa5cdb4ab67 461 if (ble_running())
Jonathan Austin 1:8aa5cdb4ab67 462 return MICROBIT_NOT_SUPPORTED;
Jonathan Austin 1:8aa5cdb4ab67 463
Jonathan Austin 1:8aa5cdb4ab67 464 if (buffer == NULL)
Jonathan Austin 1:8aa5cdb4ab67 465 return MICROBIT_INVALID_PARAMETER;
Jonathan Austin 1:8aa5cdb4ab67 466
Jonathan Austin 1:8aa5cdb4ab67 467 if (buffer->length > MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE - 1)
Jonathan Austin 1:8aa5cdb4ab67 468 return MICROBIT_INVALID_PARAMETER;
Jonathan Austin 1:8aa5cdb4ab67 469
Jonathan Austin 1:8aa5cdb4ab67 470 // Firstly, disable the Radio interrupt. We want to wait until the trasmission completes.
Jonathan Austin 1:8aa5cdb4ab67 471 NVIC_DisableIRQ(RADIO_IRQn);
Jonathan Austin 1:8aa5cdb4ab67 472
Jonathan Austin 1:8aa5cdb4ab67 473 // Turn off the transceiver.
Jonathan Austin 1:8aa5cdb4ab67 474 NRF_RADIO->EVENTS_DISABLED = 0;
Jonathan Austin 1:8aa5cdb4ab67 475 NRF_RADIO->TASKS_DISABLE = 1;
Jonathan Austin 1:8aa5cdb4ab67 476 while(NRF_RADIO->EVENTS_DISABLED == 0);
Jonathan Austin 1:8aa5cdb4ab67 477
Jonathan Austin 1:8aa5cdb4ab67 478 // Configure the radio to send the buffer provided.
Jonathan Austin 1:8aa5cdb4ab67 479 NRF_RADIO->PACKETPTR = (uint32_t) buffer;
Jonathan Austin 1:8aa5cdb4ab67 480
Jonathan Austin 1:8aa5cdb4ab67 481 // Turn on the transmitter, and wait for it to signal that it's ready to use.
Jonathan Austin 1:8aa5cdb4ab67 482 NRF_RADIO->EVENTS_READY = 0;
Jonathan Austin 1:8aa5cdb4ab67 483 NRF_RADIO->TASKS_TXEN = 1;
Jonathan Austin 1:8aa5cdb4ab67 484 while (NRF_RADIO->EVENTS_READY == 0);
Jonathan Austin 1:8aa5cdb4ab67 485
Jonathan Austin 1:8aa5cdb4ab67 486 // Start transmission and wait for end of packet.
Jonathan Austin 1:8aa5cdb4ab67 487 NRF_RADIO->TASKS_START = 1;
Jonathan Austin 1:8aa5cdb4ab67 488 NRF_RADIO->EVENTS_END = 0;
Jonathan Austin 1:8aa5cdb4ab67 489 while(NRF_RADIO->EVENTS_END == 0);
Jonathan Austin 1:8aa5cdb4ab67 490
Jonathan Austin 1:8aa5cdb4ab67 491 // Return the radio to using the default receive buffer
Jonathan Austin 1:8aa5cdb4ab67 492 NRF_RADIO->PACKETPTR = (uint32_t) rxBuf;
Jonathan Austin 1:8aa5cdb4ab67 493
Jonathan Austin 1:8aa5cdb4ab67 494 // Turn off the transmitter.
Jonathan Austin 1:8aa5cdb4ab67 495 NRF_RADIO->EVENTS_DISABLED = 0;
Jonathan Austin 1:8aa5cdb4ab67 496 NRF_RADIO->TASKS_DISABLE = 1;
Jonathan Austin 1:8aa5cdb4ab67 497 while(NRF_RADIO->EVENTS_DISABLED == 0);
Jonathan Austin 1:8aa5cdb4ab67 498
Jonathan Austin 1:8aa5cdb4ab67 499 // Start listening for the next packet
Jonathan Austin 1:8aa5cdb4ab67 500 NRF_RADIO->EVENTS_READY = 0;
Jonathan Austin 1:8aa5cdb4ab67 501 NRF_RADIO->TASKS_RXEN = 1;
Jonathan Austin 1:8aa5cdb4ab67 502 while(NRF_RADIO->EVENTS_READY == 0);
Jonathan Austin 1:8aa5cdb4ab67 503
Jonathan Austin 1:8aa5cdb4ab67 504 NRF_RADIO->EVENTS_END = 0;
Jonathan Austin 1:8aa5cdb4ab67 505 NRF_RADIO->TASKS_START = 1;
Jonathan Austin 1:8aa5cdb4ab67 506
Jonathan Austin 1:8aa5cdb4ab67 507 // Re-enable the Radio interrupt.
Jonathan Austin 1:8aa5cdb4ab67 508 NVIC_ClearPendingIRQ(RADIO_IRQn);
Jonathan Austin 1:8aa5cdb4ab67 509 NVIC_EnableIRQ(RADIO_IRQn);
Jonathan Austin 1:8aa5cdb4ab67 510
Jonathan Austin 1:8aa5cdb4ab67 511 return MICROBIT_OK;
LancasterUniversity 18:e2f92ac26450 512 }