Wendy Warne / microbit-dal

updates

Dependencies:   BLE_API mbed-dev-bin nRF51822

Fork of microbit-dal-eddystone by Martin Woolley

source/core/MicroBitDevice.cpp@61:b597fb218f84, 2016-07-13 (annotated)

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:18:40 2016 +0100
Revision:
61:b597fb218f84
Parent:
57:290a35cb9981
Child:
65:f7ebabf23e15
Synchronized with git rev 64042e4a

Author: James Devine

microbit-dal: BUGFIX cast in MicroBitSerial from int to char



There was an unnecessary cast in MicroBitSerial.read that meant error

codes would never be returned to the user application, this has now

been removed.

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 /**
Jonathan Austin 1:8aa5cdb4ab67 27 * Compatibility / portability funcitons and constants for the MicroBit DAL.
Jonathan Austin 1:8aa5cdb4ab67 28 */
Jonathan Austin 1:8aa5cdb4ab67 29 #include "MicroBitConfig.h"
Jonathan Austin 1:8aa5cdb4ab67 30 #include "MicroBitButton.h"
Jonathan Austin 1:8aa5cdb4ab67 31 #include "MicroBitDevice.h"
Jonathan Austin 1:8aa5cdb4ab67 32 #include "MicroBitFont.h"
Jonathan Austin 1:8aa5cdb4ab67 33 #include "mbed.h"
Jonathan Austin 1:8aa5cdb4ab67 34 #include "ErrorNo.h"
Jonathan Austin 1:8aa5cdb4ab67 35
Jonathan Austin 1:8aa5cdb4ab67 36 /*
Jonathan Austin 1:8aa5cdb4ab67 37 * The underlying Nordic libraries that support BLE do not compile cleanly with the stringent GCC settings we employ
Jonathan Austin 1:8aa5cdb4ab67 38 * If we're compiling under GCC, then we suppress any warnings generated from this code (but not the rest of the DAL)
Jonathan Austin 1:8aa5cdb4ab67 39 * The ARM cc compiler is more tolerant. We don't test __GNUC__ here to detect GCC as ARMCC also typically sets this
Jonathan Austin 1:8aa5cdb4ab67 40 * as a compatability option, but does not support the options used...
Jonathan Austin 1:8aa5cdb4ab67 41 */
Jonathan Austin 1:8aa5cdb4ab67 42 #if !defined(__arm)
Jonathan Austin 1:8aa5cdb4ab67 43 #pragma GCC diagnostic ignored "-Wunused-function"
Jonathan Austin 1:8aa5cdb4ab67 44 #pragma GCC diagnostic push
Jonathan Austin 1:8aa5cdb4ab67 45 #pragma GCC diagnostic ignored "-Wunused-parameter"
Jonathan Austin 1:8aa5cdb4ab67 46 #endif
Jonathan Austin 1:8aa5cdb4ab67 47
Jonathan Austin 1:8aa5cdb4ab67 48 #include "nrf_soc.h"
Jonathan Austin 1:8aa5cdb4ab67 49 #include "nrf_sdm.h"
Jonathan Austin 1:8aa5cdb4ab67 50
Jonathan Austin 1:8aa5cdb4ab67 51 /*
Jonathan Austin 1:8aa5cdb4ab67 52 * Return to our predefined compiler settings.
Jonathan Austin 1:8aa5cdb4ab67 53 */
Jonathan Austin 1:8aa5cdb4ab67 54 #if !defined(__arm)
Jonathan Austin 1:8aa5cdb4ab67 55 #pragma GCC diagnostic pop
Jonathan Austin 1:8aa5cdb4ab67 56 #endif
Jonathan Austin 1:8aa5cdb4ab67 57
Jonathan Austin 1:8aa5cdb4ab67 58 static char friendly_name[MICROBIT_NAME_LENGTH+1];
Jonathan Austin 1:8aa5cdb4ab67 59 static const uint8_t panicFace[5] = {0x1B, 0x1B,0x0,0x0E,0x11};
Jonathan Austin 1:8aa5cdb4ab67 60 static int panic_timeout = 0;
Jonathan Austin 1:8aa5cdb4ab67 61 static uint32_t random_value = 0;
Jonathan Austin 1:8aa5cdb4ab67 62
Jonathan Austin 1:8aa5cdb4ab67 63 /**
Jonathan Austin 1:8aa5cdb4ab67 64 * Determines if a BLE stack is currently running.
Jonathan Austin 1:8aa5cdb4ab67 65 *
Jonathan Austin 1:8aa5cdb4ab67 66 * @return true is a bluetooth stack is operational, false otherwise.
Jonathan Austin 1:8aa5cdb4ab67 67 */
Jonathan Austin 1:8aa5cdb4ab67 68 bool ble_running()
Jonathan Austin 1:8aa5cdb4ab67 69 {
LancasterUniversity 57:290a35cb9981 70 uint8_t t = 0;
LancasterUniversity 57:290a35cb9981 71
LancasterUniversity 57:290a35cb9981 72 #if CONFIG_ENABLED(MICROBIT_BLE_ENABLED) || CONFIG_ENABLED(MICROBIT_BLE_PAIRING_MODE)
Jonathan Austin 1:8aa5cdb4ab67 73 sd_softdevice_is_enabled(&t);
LancasterUniversity 57:290a35cb9981 74 #endif
LancasterUniversity 57:290a35cb9981 75
Jonathan Austin 1:8aa5cdb4ab67 76 return t==1;
Jonathan Austin 1:8aa5cdb4ab67 77 }
Jonathan Austin 1:8aa5cdb4ab67 78
Jonathan Austin 1:8aa5cdb4ab67 79 /**
Jonathan Austin 1:8aa5cdb4ab67 80 * Derived a unique, consistent serial number of this device from internal data.
Jonathan Austin 1:8aa5cdb4ab67 81 *
Jonathan Austin 1:8aa5cdb4ab67 82 * @return the serial number of this device.
Jonathan Austin 1:8aa5cdb4ab67 83 */
Jonathan Austin 1:8aa5cdb4ab67 84 uint32_t microbit_serial_number()
Jonathan Austin 1:8aa5cdb4ab67 85 {
Jonathan Austin 1:8aa5cdb4ab67 86 return NRF_FICR->DEVICEID[1];
Jonathan Austin 1:8aa5cdb4ab67 87 }
Jonathan Austin 1:8aa5cdb4ab67 88
Jonathan Austin 1:8aa5cdb4ab67 89 /**
Jonathan Austin 1:8aa5cdb4ab67 90 * Derive the friendly name for this device, based on its serial number.
Jonathan Austin 1:8aa5cdb4ab67 91 *
Jonathan Austin 1:8aa5cdb4ab67 92 * @return the serial number of this device.
Jonathan Austin 1:8aa5cdb4ab67 93 */
Jonathan Austin 1:8aa5cdb4ab67 94 char* microbit_friendly_name()
Jonathan Austin 1:8aa5cdb4ab67 95 {
Jonathan Austin 1:8aa5cdb4ab67 96 const uint8_t codebook[MICROBIT_NAME_LENGTH][MICROBIT_NAME_CODE_LETTERS] =
Jonathan Austin 1:8aa5cdb4ab67 97 {
Jonathan Austin 1:8aa5cdb4ab67 98 {'z', 'v', 'g', 'p', 't'},
Jonathan Austin 1:8aa5cdb4ab67 99 {'u', 'o', 'i', 'e', 'a'},
Jonathan Austin 1:8aa5cdb4ab67 100 {'z', 'v', 'g', 'p', 't'},
Jonathan Austin 1:8aa5cdb4ab67 101 {'u', 'o', 'i', 'e', 'a'},
Jonathan Austin 1:8aa5cdb4ab67 102 {'z', 'v', 'g', 'p', 't'}
Jonathan Austin 1:8aa5cdb4ab67 103 };
Jonathan Austin 1:8aa5cdb4ab67 104
Jonathan Austin 1:8aa5cdb4ab67 105 // We count right to left, so create a pointer to the end of the buffer.
Jonathan Austin 1:8aa5cdb4ab67 106 char *name = friendly_name;
Jonathan Austin 1:8aa5cdb4ab67 107 name += MICROBIT_NAME_LENGTH;
Jonathan Austin 1:8aa5cdb4ab67 108
Jonathan Austin 1:8aa5cdb4ab67 109 // Terminate the string.
Jonathan Austin 1:8aa5cdb4ab67 110 *name = 0;
Jonathan Austin 1:8aa5cdb4ab67 111
Jonathan Austin 1:8aa5cdb4ab67 112 // Derive our name from the nrf51822's unique ID.
Jonathan Austin 1:8aa5cdb4ab67 113 uint32_t n = microbit_serial_number();
Jonathan Austin 1:8aa5cdb4ab67 114 int ld = 1;
Jonathan Austin 1:8aa5cdb4ab67 115 int d = MICROBIT_NAME_CODE_LETTERS;
Jonathan Austin 1:8aa5cdb4ab67 116 int h;
Jonathan Austin 1:8aa5cdb4ab67 117
Jonathan Austin 1:8aa5cdb4ab67 118 for (int i=0; i<MICROBIT_NAME_LENGTH; i++)
Jonathan Austin 1:8aa5cdb4ab67 119 {
Jonathan Austin 1:8aa5cdb4ab67 120 h = (n % d) / ld;
Jonathan Austin 1:8aa5cdb4ab67 121 n -= h;
Jonathan Austin 1:8aa5cdb4ab67 122 d *= MICROBIT_NAME_CODE_LETTERS;
Jonathan Austin 1:8aa5cdb4ab67 123 ld *= MICROBIT_NAME_CODE_LETTERS;
Jonathan Austin 1:8aa5cdb4ab67 124 *--name = codebook[i][h];
Jonathan Austin 1:8aa5cdb4ab67 125 }
Jonathan Austin 1:8aa5cdb4ab67 126
Jonathan Austin 1:8aa5cdb4ab67 127 return friendly_name;
Jonathan Austin 1:8aa5cdb4ab67 128 }
Jonathan Austin 1:8aa5cdb4ab67 129
Jonathan Austin 1:8aa5cdb4ab67 130 /**
Jonathan Austin 1:8aa5cdb4ab67 131 * Perform a hard reset of the micro:bit.
Jonathan Austin 1:8aa5cdb4ab67 132 */
Jonathan Austin 1:8aa5cdb4ab67 133 void
Jonathan Austin 1:8aa5cdb4ab67 134 microbit_reset()
Jonathan Austin 1:8aa5cdb4ab67 135 {
Jonathan Austin 1:8aa5cdb4ab67 136 NVIC_SystemReset();
Jonathan Austin 1:8aa5cdb4ab67 137 }
Jonathan Austin 1:8aa5cdb4ab67 138
Jonathan Austin 1:8aa5cdb4ab67 139 /**
Jonathan Austin 1:8aa5cdb4ab67 140 * Determine the version of microbit-dal currently running.
Jonathan Austin 1:8aa5cdb4ab67 141 * @return a pointer to a character buffer containing a representation of the semantic version number.
Jonathan Austin 1:8aa5cdb4ab67 142 */
Jonathan Austin 1:8aa5cdb4ab67 143 const char *
Jonathan Austin 1:8aa5cdb4ab67 144 microbit_dal_version()
Jonathan Austin 1:8aa5cdb4ab67 145 {
Jonathan Austin 1:8aa5cdb4ab67 146 return MICROBIT_DAL_VERSION;
Jonathan Austin 1:8aa5cdb4ab67 147 }
Jonathan Austin 1:8aa5cdb4ab67 148
Jonathan Austin 1:8aa5cdb4ab67 149 /**
Jonathan Austin 1:8aa5cdb4ab67 150 * Defines the length of time that the device will remain in a error state before resetting.
Jonathan Austin 1:8aa5cdb4ab67 151 *
Jonathan Austin 1:8aa5cdb4ab67 152 * @param iteration The number of times the error code will be displayed before resetting. Set to zero to remain in error state forever.
Jonathan Austin 1:8aa5cdb4ab67 153 *
Jonathan Austin 1:8aa5cdb4ab67 154 * @code
Jonathan Austin 1:8aa5cdb4ab67 155 * microbit_panic_timeout(4);
Jonathan Austin 1:8aa5cdb4ab67 156 * @endcode
Jonathan Austin 1:8aa5cdb4ab67 157 */
Jonathan Austin 1:8aa5cdb4ab67 158 void microbit_panic_timeout(int iterations)
Jonathan Austin 1:8aa5cdb4ab67 159 {
Jonathan Austin 1:8aa5cdb4ab67 160 panic_timeout = iterations;
Jonathan Austin 1:8aa5cdb4ab67 161 }
Jonathan Austin 1:8aa5cdb4ab67 162
Jonathan Austin 1:8aa5cdb4ab67 163 /**
Jonathan Austin 1:8aa5cdb4ab67 164 * Disables all interrupts and user processing.
Jonathan Austin 1:8aa5cdb4ab67 165 * Displays "=(" and an accompanying status code on the default display.
LancasterUniversity 47:69f452b1a5c9 166 * @param statusCode the appropriate status code, must be in the range 0-999.
Jonathan Austin 1:8aa5cdb4ab67 167 *
Jonathan Austin 1:8aa5cdb4ab67 168 * @code
Jonathan Austin 1:8aa5cdb4ab67 169 * microbit_panic(20);
Jonathan Austin 1:8aa5cdb4ab67 170 * @endcode
Jonathan Austin 1:8aa5cdb4ab67 171 */
Jonathan Austin 1:8aa5cdb4ab67 172 void microbit_panic(int statusCode)
Jonathan Austin 1:8aa5cdb4ab67 173 {
Jonathan Austin 1:8aa5cdb4ab67 174 DigitalIn resetButton(MICROBIT_PIN_BUTTON_RESET);
Jonathan Austin 1:8aa5cdb4ab67 175 resetButton.mode(PullUp);
Jonathan Austin 1:8aa5cdb4ab67 176
Jonathan Austin 1:8aa5cdb4ab67 177 uint32_t row_mask = 0;
Jonathan Austin 1:8aa5cdb4ab67 178 uint32_t col_mask = 0;
Jonathan Austin 1:8aa5cdb4ab67 179 uint32_t row_reset = 0x01 << microbitMatrixMap.rowStart;
Jonathan Austin 1:8aa5cdb4ab67 180 uint32_t row_data = row_reset;
Jonathan Austin 1:8aa5cdb4ab67 181 uint8_t count = panic_timeout ? panic_timeout : 1;
Jonathan Austin 1:8aa5cdb4ab67 182 uint8_t strobeRow = 0;
Jonathan Austin 1:8aa5cdb4ab67 183
Jonathan Austin 1:8aa5cdb4ab67 184 row_mask = 0;
Jonathan Austin 1:8aa5cdb4ab67 185 for (int i = microbitMatrixMap.rowStart; i < microbitMatrixMap.rowStart + microbitMatrixMap.rows; i++)
Jonathan Austin 1:8aa5cdb4ab67 186 row_mask |= 0x01 << i;
Jonathan Austin 1:8aa5cdb4ab67 187
Jonathan Austin 1:8aa5cdb4ab67 188 for (int i = microbitMatrixMap.columnStart; i < microbitMatrixMap.columnStart + microbitMatrixMap.columns; i++)
Jonathan Austin 1:8aa5cdb4ab67 189 col_mask |= 0x01 << i;
Jonathan Austin 1:8aa5cdb4ab67 190
Jonathan Austin 1:8aa5cdb4ab67 191 PortOut LEDMatrix(Port0, row_mask | col_mask);
Jonathan Austin 1:8aa5cdb4ab67 192
LancasterUniversity 47:69f452b1a5c9 193 if(statusCode < 0 || statusCode > 999)
Jonathan Austin 1:8aa5cdb4ab67 194 statusCode = 0;
Jonathan Austin 1:8aa5cdb4ab67 195
Jonathan Austin 1:8aa5cdb4ab67 196 __disable_irq(); //stop ALL interrupts
Jonathan Austin 1:8aa5cdb4ab67 197
Jonathan Austin 1:8aa5cdb4ab67 198
Jonathan Austin 1:8aa5cdb4ab67 199 //point to the font stored in Flash
LancasterUniversity 47:69f452b1a5c9 200 const unsigned char* fontLocation = MicroBitFont::defaultFont;
Jonathan Austin 1:8aa5cdb4ab67 201
Jonathan Austin 1:8aa5cdb4ab67 202 //get individual digits of status code, and place it into a single array/
Jonathan Austin 1:8aa5cdb4ab67 203 const uint8_t* chars[MICROBIT_PANIC_ERROR_CHARS] = { panicFace, fontLocation+((((statusCode/100 % 10)+48)-MICROBIT_FONT_ASCII_START) * 5), fontLocation+((((statusCode/10 % 10)+48)-MICROBIT_FONT_ASCII_START) * 5), fontLocation+((((statusCode % 10)+48)-MICROBIT_FONT_ASCII_START) * 5)};
Jonathan Austin 1:8aa5cdb4ab67 204
Jonathan Austin 1:8aa5cdb4ab67 205 while(count)
Jonathan Austin 1:8aa5cdb4ab67 206 {
Jonathan Austin 1:8aa5cdb4ab67 207 //iterate through our chars :)
Jonathan Austin 1:8aa5cdb4ab67 208 for(int characterCount = 0; characterCount < MICROBIT_PANIC_ERROR_CHARS; characterCount++)
Jonathan Austin 1:8aa5cdb4ab67 209 {
Jonathan Austin 1:8aa5cdb4ab67 210 int outerCount = 0;
Jonathan Austin 1:8aa5cdb4ab67 211
Jonathan Austin 1:8aa5cdb4ab67 212 //display the current character
Jonathan Austin 1:8aa5cdb4ab67 213 while(outerCount < 500)
Jonathan Austin 1:8aa5cdb4ab67 214 {
Jonathan Austin 1:8aa5cdb4ab67 215 uint32_t col_data = 0;
Jonathan Austin 1:8aa5cdb4ab67 216
Jonathan Austin 1:8aa5cdb4ab67 217 int i = 0;
Jonathan Austin 1:8aa5cdb4ab67 218
Jonathan Austin 1:8aa5cdb4ab67 219 //if we have hit the row limit - reset both the bit mask and the row variable
Jonathan Austin 1:8aa5cdb4ab67 220 if(strobeRow == microbitMatrixMap.rows)
Jonathan Austin 1:8aa5cdb4ab67 221 {
Jonathan Austin 1:8aa5cdb4ab67 222 strobeRow = 0;
Jonathan Austin 1:8aa5cdb4ab67 223 row_data = row_reset;
Jonathan Austin 1:8aa5cdb4ab67 224 }
Jonathan Austin 1:8aa5cdb4ab67 225
Jonathan Austin 1:8aa5cdb4ab67 226 // Calculate the bitpattern to write.
Jonathan Austin 1:8aa5cdb4ab67 227 for (i = 0; i < microbitMatrixMap.columns; i++)
Jonathan Austin 1:8aa5cdb4ab67 228 {
Jonathan Austin 1:8aa5cdb4ab67 229 int index = (i * microbitMatrixMap.rows) + strobeRow;
Jonathan Austin 1:8aa5cdb4ab67 230
Jonathan Austin 1:8aa5cdb4ab67 231 int bitMsk = 0x10 >> microbitMatrixMap.map[index].x; //chars are right aligned but read left to right
Jonathan Austin 1:8aa5cdb4ab67 232 int y = microbitMatrixMap.map[index].y;
Jonathan Austin 1:8aa5cdb4ab67 233
Jonathan Austin 1:8aa5cdb4ab67 234 if(chars[characterCount][y] & bitMsk)
Jonathan Austin 1:8aa5cdb4ab67 235 col_data |= (1 << i);
Jonathan Austin 1:8aa5cdb4ab67 236 }
Jonathan Austin 1:8aa5cdb4ab67 237
Jonathan Austin 1:8aa5cdb4ab67 238 col_data = ~col_data << microbitMatrixMap.columnStart & col_mask;
Jonathan Austin 1:8aa5cdb4ab67 239
LancasterUniversity 47:69f452b1a5c9 240 if(chars[characterCount] == chars[(characterCount - 1) % MICROBIT_PANIC_ERROR_CHARS] && outerCount < 50)
LancasterUniversity 47:69f452b1a5c9 241 LEDMatrix = 0;
LancasterUniversity 47:69f452b1a5c9 242 else
LancasterUniversity 47:69f452b1a5c9 243 LEDMatrix = col_data | row_data;
Jonathan Austin 1:8aa5cdb4ab67 244
Jonathan Austin 1:8aa5cdb4ab67 245 //burn cycles
LancasterUniversity 47:69f452b1a5c9 246 i = 2000;
Jonathan Austin 1:8aa5cdb4ab67 247 while(i>0)
Jonathan Austin 1:8aa5cdb4ab67 248 {
Jonathan Austin 1:8aa5cdb4ab67 249 // Check if the reset button has been pressed. Interrupts are disabled, so the normal method can't be relied upon...
Jonathan Austin 1:8aa5cdb4ab67 250 if (resetButton == 0)
Jonathan Austin 1:8aa5cdb4ab67 251 microbit_reset();
Jonathan Austin 1:8aa5cdb4ab67 252
Jonathan Austin 1:8aa5cdb4ab67 253 i--;
Jonathan Austin 1:8aa5cdb4ab67 254 }
Jonathan Austin 1:8aa5cdb4ab67 255
Jonathan Austin 1:8aa5cdb4ab67 256 //update the bit mask and row count
Jonathan Austin 1:8aa5cdb4ab67 257 row_data <<= 1;
Jonathan Austin 1:8aa5cdb4ab67 258 strobeRow++;
Jonathan Austin 1:8aa5cdb4ab67 259 outerCount++;
Jonathan Austin 1:8aa5cdb4ab67 260 }
Jonathan Austin 1:8aa5cdb4ab67 261 }
Jonathan Austin 1:8aa5cdb4ab67 262
Jonathan Austin 1:8aa5cdb4ab67 263 if (panic_timeout)
Jonathan Austin 1:8aa5cdb4ab67 264 count--;
Jonathan Austin 1:8aa5cdb4ab67 265 }
Jonathan Austin 1:8aa5cdb4ab67 266
Jonathan Austin 1:8aa5cdb4ab67 267 microbit_reset();
Jonathan Austin 1:8aa5cdb4ab67 268 }
Jonathan Austin 1:8aa5cdb4ab67 269
Jonathan Austin 1:8aa5cdb4ab67 270 /**
Jonathan Austin 1:8aa5cdb4ab67 271 * Generate a random number in the given range.
Jonathan Austin 1:8aa5cdb4ab67 272 * We use a simple Galois LFSR random number generator here,
Jonathan Austin 1:8aa5cdb4ab67 273 * as a Galois LFSR is sufficient for our applications, and much more lightweight
Jonathan Austin 1:8aa5cdb4ab67 274 * than the hardware random number generator built int the processor, which takes
Jonathan Austin 1:8aa5cdb4ab67 275 * a long time and uses a lot of energy.
Jonathan Austin 1:8aa5cdb4ab67 276 *
Jonathan Austin 1:8aa5cdb4ab67 277 * KIDS: You shouldn't use this is the real world to generte cryptographic keys though...
Jonathan Austin 1:8aa5cdb4ab67 278 * have a think why not. :-)
Jonathan Austin 1:8aa5cdb4ab67 279 *
Jonathan Austin 1:8aa5cdb4ab67 280 * @param max the upper range to generate a number for. This number cannot be negative.
Jonathan Austin 1:8aa5cdb4ab67 281 *
Jonathan Austin 1:8aa5cdb4ab67 282 * @return A random, natural number between 0 and the max-1. Or MICROBIT_INVALID_VALUE if max is <= 0.
Jonathan Austin 1:8aa5cdb4ab67 283 *
Jonathan Austin 1:8aa5cdb4ab67 284 * @code
Jonathan Austin 1:8aa5cdb4ab67 285 * microbit_random(200); //a number between 0 and 199
Jonathan Austin 1:8aa5cdb4ab67 286 * @endcode
Jonathan Austin 1:8aa5cdb4ab67 287 */
Jonathan Austin 1:8aa5cdb4ab67 288 int microbit_random(int max)
Jonathan Austin 1:8aa5cdb4ab67 289 {
Jonathan Austin 1:8aa5cdb4ab67 290 uint32_t m, result;
Jonathan Austin 1:8aa5cdb4ab67 291
Jonathan Austin 1:8aa5cdb4ab67 292 if(max <= 0)
Jonathan Austin 1:8aa5cdb4ab67 293 return MICROBIT_INVALID_PARAMETER;
Jonathan Austin 1:8aa5cdb4ab67 294
Jonathan Austin 1:8aa5cdb4ab67 295 // Our maximum return value is actually one less than passed
Jonathan Austin 1:8aa5cdb4ab67 296 max--;
Jonathan Austin 1:8aa5cdb4ab67 297
Jonathan Austin 1:8aa5cdb4ab67 298 do {
Jonathan Austin 1:8aa5cdb4ab67 299 m = (uint32_t)max;
Jonathan Austin 1:8aa5cdb4ab67 300 result = 0;
Jonathan Austin 1:8aa5cdb4ab67 301 do {
Jonathan Austin 1:8aa5cdb4ab67 302 // Cycle the LFSR (Linear Feedback Shift Register).
Jonathan Austin 1:8aa5cdb4ab67 303 // We use an optimal sequence with a period of 2^32-1, as defined by Bruce Schneier here (a true legend in the field!),
Jonathan Austin 1:8aa5cdb4ab67 304 // For those interested, it's documented in his paper:
Jonathan Austin 1:8aa5cdb4ab67 305 // "Pseudo-Random Sequence Generator for 32-Bit CPUs: A fast, machine-independent generator for 32-bit Microprocessors"
Jonathan Austin 1:8aa5cdb4ab67 306 // https://www.schneier.com/paper-pseudorandom-sequence.html
Jonathan Austin 1:8aa5cdb4ab67 307 uint32_t rnd = random_value;
Jonathan Austin 1:8aa5cdb4ab67 308
Jonathan Austin 1:8aa5cdb4ab67 309 rnd = ((((rnd >> 31)
Jonathan Austin 1:8aa5cdb4ab67 310 ^ (rnd >> 6)
Jonathan Austin 1:8aa5cdb4ab67 311 ^ (rnd >> 4)
Jonathan Austin 1:8aa5cdb4ab67 312 ^ (rnd >> 2)
Jonathan Austin 1:8aa5cdb4ab67 313 ^ (rnd >> 1)
Jonathan Austin 1:8aa5cdb4ab67 314 ^ rnd)
Jonathan Austin 1:8aa5cdb4ab67 315 & 0x0000001)
Jonathan Austin 1:8aa5cdb4ab67 316 << 31 )
Jonathan Austin 1:8aa5cdb4ab67 317 | (rnd >> 1);
Jonathan Austin 1:8aa5cdb4ab67 318
Jonathan Austin 1:8aa5cdb4ab67 319 random_value = rnd;
Jonathan Austin 1:8aa5cdb4ab67 320
Jonathan Austin 1:8aa5cdb4ab67 321 result = ((result << 1) | (rnd & 0x00000001));
Jonathan Austin 1:8aa5cdb4ab67 322 } while(m >>= 1);
Jonathan Austin 1:8aa5cdb4ab67 323 } while (result > (uint32_t)max);
Jonathan Austin 1:8aa5cdb4ab67 324
Jonathan Austin 1:8aa5cdb4ab67 325 return result;
Jonathan Austin 1:8aa5cdb4ab67 326 }
Jonathan Austin 1:8aa5cdb4ab67 327
Jonathan Austin 1:8aa5cdb4ab67 328 /**
Jonathan Austin 1:8aa5cdb4ab67 329 * Seed the random number generator (RNG).
Jonathan Austin 1:8aa5cdb4ab67 330 *
Jonathan Austin 1:8aa5cdb4ab67 331 * This function uses the NRF51822's in built cryptographic random number generator to seed a Galois LFSR.
Jonathan Austin 1:8aa5cdb4ab67 332 * We do this as the hardware RNG is relatively high power, and is locked out by the BLE stack internally,
Jonathan Austin 1:8aa5cdb4ab67 333 * with a less than optimal application interface. A Galois LFSR is sufficient for our
Jonathan Austin 1:8aa5cdb4ab67 334 * applications, and much more lightweight.
Jonathan Austin 1:8aa5cdb4ab67 335 */
Jonathan Austin 1:8aa5cdb4ab67 336 void microbit_seed_random()
Jonathan Austin 1:8aa5cdb4ab67 337 {
Jonathan Austin 1:8aa5cdb4ab67 338 random_value = 0;
Jonathan Austin 1:8aa5cdb4ab67 339
Jonathan Austin 1:8aa5cdb4ab67 340 if(ble_running())
Jonathan Austin 1:8aa5cdb4ab67 341 {
Jonathan Austin 1:8aa5cdb4ab67 342 // If Bluetooth is enabled, we need to go through the Nordic software to safely do this.
Jonathan Austin 1:8aa5cdb4ab67 343 uint32_t result = sd_rand_application_vector_get((uint8_t*)&random_value, sizeof(random_value));
Jonathan Austin 1:8aa5cdb4ab67 344
Jonathan Austin 1:8aa5cdb4ab67 345 // If we couldn't get the random bytes then at least make the seed non-zero.
Jonathan Austin 1:8aa5cdb4ab67 346 if (result != NRF_SUCCESS)
Jonathan Austin 1:8aa5cdb4ab67 347 random_value = 0xBBC5EED;
Jonathan Austin 1:8aa5cdb4ab67 348 }
Jonathan Austin 1:8aa5cdb4ab67 349 else
Jonathan Austin 1:8aa5cdb4ab67 350 {
Jonathan Austin 1:8aa5cdb4ab67 351 // Othwerwise we can access the hardware RNG directly.
Jonathan Austin 1:8aa5cdb4ab67 352
Jonathan Austin 1:8aa5cdb4ab67 353 // Start the Random number generator. No need to leave it running... I hope. :-)
Jonathan Austin 1:8aa5cdb4ab67 354 NRF_RNG->TASKS_START = 1;
Jonathan Austin 1:8aa5cdb4ab67 355
Jonathan Austin 1:8aa5cdb4ab67 356 for(int i = 0; i < 4; i++)
Jonathan Austin 1:8aa5cdb4ab67 357 {
Jonathan Austin 1:8aa5cdb4ab67 358 // Clear the VALRDY EVENT
Jonathan Austin 1:8aa5cdb4ab67 359 NRF_RNG->EVENTS_VALRDY = 0;
Jonathan Austin 1:8aa5cdb4ab67 360
Jonathan Austin 1:8aa5cdb4ab67 361 // Wait for a number ot be generated.
Jonathan Austin 1:8aa5cdb4ab67 362 while(NRF_RNG->EVENTS_VALRDY == 0);
Jonathan Austin 1:8aa5cdb4ab67 363
Jonathan Austin 1:8aa5cdb4ab67 364 random_value = (random_value << 8) | ((int) NRF_RNG->VALUE);
Jonathan Austin 1:8aa5cdb4ab67 365 }
Jonathan Austin 1:8aa5cdb4ab67 366
Jonathan Austin 1:8aa5cdb4ab67 367 // Disable the generator to save power.
Jonathan Austin 1:8aa5cdb4ab67 368 NRF_RNG->TASKS_STOP = 1;
Jonathan Austin 1:8aa5cdb4ab67 369 }
Jonathan Austin 1:8aa5cdb4ab67 370 }
Jonathan Austin 1:8aa5cdb4ab67 371
Jonathan Austin 1:8aa5cdb4ab67 372 /**
Jonathan Austin 1:8aa5cdb4ab67 373 * Seed the pseudo random number generator (RNG) using the given 32-bit value.
Jonathan Austin 1:8aa5cdb4ab67 374 * This function does not use the NRF51822's in built cryptographic random number generator.
Jonathan Austin 1:8aa5cdb4ab67 375 *
Jonathan Austin 1:8aa5cdb4ab67 376 * @param seed The value to use as a seed.
Jonathan Austin 1:8aa5cdb4ab67 377 */
Jonathan Austin 1:8aa5cdb4ab67 378 void microbit_seed_random(uint32_t seed)
Jonathan Austin 1:8aa5cdb4ab67 379 {
Jonathan Austin 1:8aa5cdb4ab67 380 random_value = seed;
LancasterUniversity 47:69f452b1a5c9 381 }