updates

Dependencies:   BLE_API mbed-dev-bin nRF51822

Fork of microbit-dal-eddystone by Martin Woolley

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:18:07 2016 +0100
Revision:
29:62f8b007debf
Parent:
1:8aa5cdb4ab67
Child:
47:69f452b1a5c9
Synchronized with git rev 0048a9ac
Author: James Devine
microbit-dal: fixed UART service buffer sizing, and re-enabled config options for default services

There was a perspective mismatch with the UART service, where the
actual buffer size given in the constructor, did not reflect the size
of the user buffer that was available to the application. This was not
documented, and hence cause confusion. The patch applied in this
commit, increments the given buffer sizes by one, so that the
application buffer has the available size given in the constructor.

Additionally, some configuration options were lost during the component
refactor, these have now been restored.

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 {
Jonathan Austin 1:8aa5cdb4ab67 70 uint8_t t;
Jonathan Austin 1:8aa5cdb4ab67 71 sd_softdevice_is_enabled(&t);
Jonathan Austin 1:8aa5cdb4ab67 72 return t==1;
Jonathan Austin 1:8aa5cdb4ab67 73 }
Jonathan Austin 1:8aa5cdb4ab67 74
Jonathan Austin 1:8aa5cdb4ab67 75 /**
Jonathan Austin 1:8aa5cdb4ab67 76 * Derived a unique, consistent serial number of this device from internal data.
Jonathan Austin 1:8aa5cdb4ab67 77 *
Jonathan Austin 1:8aa5cdb4ab67 78 * @return the serial number of this device.
Jonathan Austin 1:8aa5cdb4ab67 79 */
Jonathan Austin 1:8aa5cdb4ab67 80 uint32_t microbit_serial_number()
Jonathan Austin 1:8aa5cdb4ab67 81 {
Jonathan Austin 1:8aa5cdb4ab67 82 return NRF_FICR->DEVICEID[1];
Jonathan Austin 1:8aa5cdb4ab67 83 }
Jonathan Austin 1:8aa5cdb4ab67 84
Jonathan Austin 1:8aa5cdb4ab67 85 /**
Jonathan Austin 1:8aa5cdb4ab67 86 * Derive the friendly name for this device, based on its serial number.
Jonathan Austin 1:8aa5cdb4ab67 87 *
Jonathan Austin 1:8aa5cdb4ab67 88 * @return the serial number of this device.
Jonathan Austin 1:8aa5cdb4ab67 89 */
Jonathan Austin 1:8aa5cdb4ab67 90 char* microbit_friendly_name()
Jonathan Austin 1:8aa5cdb4ab67 91 {
Jonathan Austin 1:8aa5cdb4ab67 92 const uint8_t codebook[MICROBIT_NAME_LENGTH][MICROBIT_NAME_CODE_LETTERS] =
Jonathan Austin 1:8aa5cdb4ab67 93 {
Jonathan Austin 1:8aa5cdb4ab67 94 {'z', 'v', 'g', 'p', 't'},
Jonathan Austin 1:8aa5cdb4ab67 95 {'u', 'o', 'i', 'e', 'a'},
Jonathan Austin 1:8aa5cdb4ab67 96 {'z', 'v', 'g', 'p', 't'},
Jonathan Austin 1:8aa5cdb4ab67 97 {'u', 'o', 'i', 'e', 'a'},
Jonathan Austin 1:8aa5cdb4ab67 98 {'z', 'v', 'g', 'p', 't'}
Jonathan Austin 1:8aa5cdb4ab67 99 };
Jonathan Austin 1:8aa5cdb4ab67 100
Jonathan Austin 1:8aa5cdb4ab67 101 // We count right to left, so create a pointer to the end of the buffer.
Jonathan Austin 1:8aa5cdb4ab67 102 char *name = friendly_name;
Jonathan Austin 1:8aa5cdb4ab67 103 name += MICROBIT_NAME_LENGTH;
Jonathan Austin 1:8aa5cdb4ab67 104
Jonathan Austin 1:8aa5cdb4ab67 105 // Terminate the string.
Jonathan Austin 1:8aa5cdb4ab67 106 *name = 0;
Jonathan Austin 1:8aa5cdb4ab67 107
Jonathan Austin 1:8aa5cdb4ab67 108 // Derive our name from the nrf51822's unique ID.
Jonathan Austin 1:8aa5cdb4ab67 109 uint32_t n = microbit_serial_number();
Jonathan Austin 1:8aa5cdb4ab67 110 int ld = 1;
Jonathan Austin 1:8aa5cdb4ab67 111 int d = MICROBIT_NAME_CODE_LETTERS;
Jonathan Austin 1:8aa5cdb4ab67 112 int h;
Jonathan Austin 1:8aa5cdb4ab67 113
Jonathan Austin 1:8aa5cdb4ab67 114 for (int i=0; i<MICROBIT_NAME_LENGTH; i++)
Jonathan Austin 1:8aa5cdb4ab67 115 {
Jonathan Austin 1:8aa5cdb4ab67 116 h = (n % d) / ld;
Jonathan Austin 1:8aa5cdb4ab67 117 n -= h;
Jonathan Austin 1:8aa5cdb4ab67 118 d *= MICROBIT_NAME_CODE_LETTERS;
Jonathan Austin 1:8aa5cdb4ab67 119 ld *= MICROBIT_NAME_CODE_LETTERS;
Jonathan Austin 1:8aa5cdb4ab67 120 *--name = codebook[i][h];
Jonathan Austin 1:8aa5cdb4ab67 121 }
Jonathan Austin 1:8aa5cdb4ab67 122
Jonathan Austin 1:8aa5cdb4ab67 123 return friendly_name;
Jonathan Austin 1:8aa5cdb4ab67 124 }
Jonathan Austin 1:8aa5cdb4ab67 125
Jonathan Austin 1:8aa5cdb4ab67 126 /**
Jonathan Austin 1:8aa5cdb4ab67 127 * Perform a hard reset of the micro:bit.
Jonathan Austin 1:8aa5cdb4ab67 128 */
Jonathan Austin 1:8aa5cdb4ab67 129 void
Jonathan Austin 1:8aa5cdb4ab67 130 microbit_reset()
Jonathan Austin 1:8aa5cdb4ab67 131 {
Jonathan Austin 1:8aa5cdb4ab67 132 NVIC_SystemReset();
Jonathan Austin 1:8aa5cdb4ab67 133 }
Jonathan Austin 1:8aa5cdb4ab67 134
Jonathan Austin 1:8aa5cdb4ab67 135 /**
Jonathan Austin 1:8aa5cdb4ab67 136 * Determine the version of microbit-dal currently running.
Jonathan Austin 1:8aa5cdb4ab67 137 * @return a pointer to a character buffer containing a representation of the semantic version number.
Jonathan Austin 1:8aa5cdb4ab67 138 */
Jonathan Austin 1:8aa5cdb4ab67 139 const char *
Jonathan Austin 1:8aa5cdb4ab67 140 microbit_dal_version()
Jonathan Austin 1:8aa5cdb4ab67 141 {
Jonathan Austin 1:8aa5cdb4ab67 142 return MICROBIT_DAL_VERSION;
Jonathan Austin 1:8aa5cdb4ab67 143 }
Jonathan Austin 1:8aa5cdb4ab67 144
Jonathan Austin 1:8aa5cdb4ab67 145 /**
Jonathan Austin 1:8aa5cdb4ab67 146 * Defines the length of time that the device will remain in a error state before resetting.
Jonathan Austin 1:8aa5cdb4ab67 147 *
Jonathan Austin 1:8aa5cdb4ab67 148 * @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 149 *
Jonathan Austin 1:8aa5cdb4ab67 150 * @code
Jonathan Austin 1:8aa5cdb4ab67 151 * microbit_panic_timeout(4);
Jonathan Austin 1:8aa5cdb4ab67 152 * @endcode
Jonathan Austin 1:8aa5cdb4ab67 153 */
Jonathan Austin 1:8aa5cdb4ab67 154 void microbit_panic_timeout(int iterations)
Jonathan Austin 1:8aa5cdb4ab67 155 {
Jonathan Austin 1:8aa5cdb4ab67 156 panic_timeout = iterations;
Jonathan Austin 1:8aa5cdb4ab67 157 }
Jonathan Austin 1:8aa5cdb4ab67 158
Jonathan Austin 1:8aa5cdb4ab67 159 /**
Jonathan Austin 1:8aa5cdb4ab67 160 * Disables all interrupts and user processing.
Jonathan Austin 1:8aa5cdb4ab67 161 * Displays "=(" and an accompanying status code on the default display.
Jonathan Austin 1:8aa5cdb4ab67 162 * @param statusCode the appropriate status code - 0 means no code will be displayed. Status codes must be in the range 0-255.
Jonathan Austin 1:8aa5cdb4ab67 163 *
Jonathan Austin 1:8aa5cdb4ab67 164 * @code
Jonathan Austin 1:8aa5cdb4ab67 165 * microbit_panic(20);
Jonathan Austin 1:8aa5cdb4ab67 166 * @endcode
Jonathan Austin 1:8aa5cdb4ab67 167 */
Jonathan Austin 1:8aa5cdb4ab67 168 void microbit_panic(int statusCode)
Jonathan Austin 1:8aa5cdb4ab67 169 {
Jonathan Austin 1:8aa5cdb4ab67 170 DigitalIn resetButton(MICROBIT_PIN_BUTTON_RESET);
Jonathan Austin 1:8aa5cdb4ab67 171 resetButton.mode(PullUp);
Jonathan Austin 1:8aa5cdb4ab67 172
Jonathan Austin 1:8aa5cdb4ab67 173 uint32_t row_mask = 0;
Jonathan Austin 1:8aa5cdb4ab67 174 uint32_t col_mask = 0;
Jonathan Austin 1:8aa5cdb4ab67 175 uint32_t row_reset = 0x01 << microbitMatrixMap.rowStart;
Jonathan Austin 1:8aa5cdb4ab67 176 uint32_t row_data = row_reset;
Jonathan Austin 1:8aa5cdb4ab67 177 uint8_t count = panic_timeout ? panic_timeout : 1;
Jonathan Austin 1:8aa5cdb4ab67 178 uint8_t strobeRow = 0;
Jonathan Austin 1:8aa5cdb4ab67 179
Jonathan Austin 1:8aa5cdb4ab67 180 row_mask = 0;
Jonathan Austin 1:8aa5cdb4ab67 181 for (int i = microbitMatrixMap.rowStart; i < microbitMatrixMap.rowStart + microbitMatrixMap.rows; i++)
Jonathan Austin 1:8aa5cdb4ab67 182 row_mask |= 0x01 << i;
Jonathan Austin 1:8aa5cdb4ab67 183
Jonathan Austin 1:8aa5cdb4ab67 184 for (int i = microbitMatrixMap.columnStart; i < microbitMatrixMap.columnStart + microbitMatrixMap.columns; i++)
Jonathan Austin 1:8aa5cdb4ab67 185 col_mask |= 0x01 << i;
Jonathan Austin 1:8aa5cdb4ab67 186
Jonathan Austin 1:8aa5cdb4ab67 187 PortOut LEDMatrix(Port0, row_mask | col_mask);
Jonathan Austin 1:8aa5cdb4ab67 188
Jonathan Austin 1:8aa5cdb4ab67 189 if(statusCode < 0 || statusCode > 255)
Jonathan Austin 1:8aa5cdb4ab67 190 statusCode = 0;
Jonathan Austin 1:8aa5cdb4ab67 191
Jonathan Austin 1:8aa5cdb4ab67 192 __disable_irq(); //stop ALL interrupts
Jonathan Austin 1:8aa5cdb4ab67 193
Jonathan Austin 1:8aa5cdb4ab67 194
Jonathan Austin 1:8aa5cdb4ab67 195 //point to the font stored in Flash
Jonathan Austin 1:8aa5cdb4ab67 196 const unsigned char * fontLocation = MicroBitFont::defaultFont;
Jonathan Austin 1:8aa5cdb4ab67 197
Jonathan Austin 1:8aa5cdb4ab67 198 //get individual digits of status code, and place it into a single array/
Jonathan Austin 1:8aa5cdb4ab67 199 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 200
Jonathan Austin 1:8aa5cdb4ab67 201 //enter infinite loop.
Jonathan Austin 1:8aa5cdb4ab67 202 while(count)
Jonathan Austin 1:8aa5cdb4ab67 203 {
Jonathan Austin 1:8aa5cdb4ab67 204 //iterate through our chars :)
Jonathan Austin 1:8aa5cdb4ab67 205 for(int characterCount = 0; characterCount < MICROBIT_PANIC_ERROR_CHARS; characterCount++)
Jonathan Austin 1:8aa5cdb4ab67 206 {
Jonathan Austin 1:8aa5cdb4ab67 207 int outerCount = 0;
Jonathan Austin 1:8aa5cdb4ab67 208
Jonathan Austin 1:8aa5cdb4ab67 209 //display the current character
Jonathan Austin 1:8aa5cdb4ab67 210 while(outerCount < 500)
Jonathan Austin 1:8aa5cdb4ab67 211 {
Jonathan Austin 1:8aa5cdb4ab67 212 uint32_t col_data = 0;
Jonathan Austin 1:8aa5cdb4ab67 213
Jonathan Austin 1:8aa5cdb4ab67 214 int i = 0;
Jonathan Austin 1:8aa5cdb4ab67 215
Jonathan Austin 1:8aa5cdb4ab67 216 //if we have hit the row limit - reset both the bit mask and the row variable
Jonathan Austin 1:8aa5cdb4ab67 217 if(strobeRow == microbitMatrixMap.rows)
Jonathan Austin 1:8aa5cdb4ab67 218 {
Jonathan Austin 1:8aa5cdb4ab67 219 strobeRow = 0;
Jonathan Austin 1:8aa5cdb4ab67 220 row_data = row_reset;
Jonathan Austin 1:8aa5cdb4ab67 221 }
Jonathan Austin 1:8aa5cdb4ab67 222
Jonathan Austin 1:8aa5cdb4ab67 223 // Calculate the bitpattern to write.
Jonathan Austin 1:8aa5cdb4ab67 224 for (i = 0; i < microbitMatrixMap.columns; i++)
Jonathan Austin 1:8aa5cdb4ab67 225 {
Jonathan Austin 1:8aa5cdb4ab67 226 int index = (i * microbitMatrixMap.rows) + strobeRow;
Jonathan Austin 1:8aa5cdb4ab67 227
Jonathan Austin 1:8aa5cdb4ab67 228 int bitMsk = 0x10 >> microbitMatrixMap.map[index].x; //chars are right aligned but read left to right
Jonathan Austin 1:8aa5cdb4ab67 229 int y = microbitMatrixMap.map[index].y;
Jonathan Austin 1:8aa5cdb4ab67 230
Jonathan Austin 1:8aa5cdb4ab67 231 if(chars[characterCount][y] & bitMsk)
Jonathan Austin 1:8aa5cdb4ab67 232 col_data |= (1 << i);
Jonathan Austin 1:8aa5cdb4ab67 233 }
Jonathan Austin 1:8aa5cdb4ab67 234
Jonathan Austin 1:8aa5cdb4ab67 235 col_data = ~col_data << microbitMatrixMap.columnStart & col_mask;
Jonathan Austin 1:8aa5cdb4ab67 236
Jonathan Austin 1:8aa5cdb4ab67 237 LEDMatrix = col_data | row_data;
Jonathan Austin 1:8aa5cdb4ab67 238
Jonathan Austin 1:8aa5cdb4ab67 239 //burn cycles
Jonathan Austin 1:8aa5cdb4ab67 240 i = 1000;
Jonathan Austin 1:8aa5cdb4ab67 241 while(i>0)
Jonathan Austin 1:8aa5cdb4ab67 242 {
Jonathan Austin 1:8aa5cdb4ab67 243 // Check if the reset button has been pressed. Interrupts are disabled, so the normal method can't be relied upon...
Jonathan Austin 1:8aa5cdb4ab67 244 if (resetButton == 0)
Jonathan Austin 1:8aa5cdb4ab67 245 microbit_reset();
Jonathan Austin 1:8aa5cdb4ab67 246
Jonathan Austin 1:8aa5cdb4ab67 247 i--;
Jonathan Austin 1:8aa5cdb4ab67 248 }
Jonathan Austin 1:8aa5cdb4ab67 249
Jonathan Austin 1:8aa5cdb4ab67 250 //update the bit mask and row count
Jonathan Austin 1:8aa5cdb4ab67 251 row_data <<= 1;
Jonathan Austin 1:8aa5cdb4ab67 252 strobeRow++;
Jonathan Austin 1:8aa5cdb4ab67 253 outerCount++;
Jonathan Austin 1:8aa5cdb4ab67 254 }
Jonathan Austin 1:8aa5cdb4ab67 255 }
Jonathan Austin 1:8aa5cdb4ab67 256
Jonathan Austin 1:8aa5cdb4ab67 257 if (panic_timeout)
Jonathan Austin 1:8aa5cdb4ab67 258 count--;
Jonathan Austin 1:8aa5cdb4ab67 259 }
Jonathan Austin 1:8aa5cdb4ab67 260
Jonathan Austin 1:8aa5cdb4ab67 261 microbit_reset();
Jonathan Austin 1:8aa5cdb4ab67 262 }
Jonathan Austin 1:8aa5cdb4ab67 263
Jonathan Austin 1:8aa5cdb4ab67 264 /**
Jonathan Austin 1:8aa5cdb4ab67 265 * Generate a random number in the given range.
Jonathan Austin 1:8aa5cdb4ab67 266 * We use a simple Galois LFSR random number generator here,
Jonathan Austin 1:8aa5cdb4ab67 267 * as a Galois LFSR is sufficient for our applications, and much more lightweight
Jonathan Austin 1:8aa5cdb4ab67 268 * than the hardware random number generator built int the processor, which takes
Jonathan Austin 1:8aa5cdb4ab67 269 * a long time and uses a lot of energy.
Jonathan Austin 1:8aa5cdb4ab67 270 *
Jonathan Austin 1:8aa5cdb4ab67 271 * KIDS: You shouldn't use this is the real world to generte cryptographic keys though...
Jonathan Austin 1:8aa5cdb4ab67 272 * have a think why not. :-)
Jonathan Austin 1:8aa5cdb4ab67 273 *
Jonathan Austin 1:8aa5cdb4ab67 274 * @param max the upper range to generate a number for. This number cannot be negative.
Jonathan Austin 1:8aa5cdb4ab67 275 *
Jonathan Austin 1:8aa5cdb4ab67 276 * @return A random, natural number between 0 and the max-1. Or MICROBIT_INVALID_VALUE if max is <= 0.
Jonathan Austin 1:8aa5cdb4ab67 277 *
Jonathan Austin 1:8aa5cdb4ab67 278 * @code
Jonathan Austin 1:8aa5cdb4ab67 279 * microbit_random(200); //a number between 0 and 199
Jonathan Austin 1:8aa5cdb4ab67 280 * @endcode
Jonathan Austin 1:8aa5cdb4ab67 281 */
Jonathan Austin 1:8aa5cdb4ab67 282 int microbit_random(int max)
Jonathan Austin 1:8aa5cdb4ab67 283 {
Jonathan Austin 1:8aa5cdb4ab67 284 uint32_t m, result;
Jonathan Austin 1:8aa5cdb4ab67 285
Jonathan Austin 1:8aa5cdb4ab67 286 if(max <= 0)
Jonathan Austin 1:8aa5cdb4ab67 287 return MICROBIT_INVALID_PARAMETER;
Jonathan Austin 1:8aa5cdb4ab67 288
Jonathan Austin 1:8aa5cdb4ab67 289 // Our maximum return value is actually one less than passed
Jonathan Austin 1:8aa5cdb4ab67 290 max--;
Jonathan Austin 1:8aa5cdb4ab67 291
Jonathan Austin 1:8aa5cdb4ab67 292 do {
Jonathan Austin 1:8aa5cdb4ab67 293 m = (uint32_t)max;
Jonathan Austin 1:8aa5cdb4ab67 294 result = 0;
Jonathan Austin 1:8aa5cdb4ab67 295 do {
Jonathan Austin 1:8aa5cdb4ab67 296 // Cycle the LFSR (Linear Feedback Shift Register).
Jonathan Austin 1:8aa5cdb4ab67 297 // 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 298 // For those interested, it's documented in his paper:
Jonathan Austin 1:8aa5cdb4ab67 299 // "Pseudo-Random Sequence Generator for 32-Bit CPUs: A fast, machine-independent generator for 32-bit Microprocessors"
Jonathan Austin 1:8aa5cdb4ab67 300 // https://www.schneier.com/paper-pseudorandom-sequence.html
Jonathan Austin 1:8aa5cdb4ab67 301 uint32_t rnd = random_value;
Jonathan Austin 1:8aa5cdb4ab67 302
Jonathan Austin 1:8aa5cdb4ab67 303 rnd = ((((rnd >> 31)
Jonathan Austin 1:8aa5cdb4ab67 304 ^ (rnd >> 6)
Jonathan Austin 1:8aa5cdb4ab67 305 ^ (rnd >> 4)
Jonathan Austin 1:8aa5cdb4ab67 306 ^ (rnd >> 2)
Jonathan Austin 1:8aa5cdb4ab67 307 ^ (rnd >> 1)
Jonathan Austin 1:8aa5cdb4ab67 308 ^ rnd)
Jonathan Austin 1:8aa5cdb4ab67 309 & 0x0000001)
Jonathan Austin 1:8aa5cdb4ab67 310 << 31 )
Jonathan Austin 1:8aa5cdb4ab67 311 | (rnd >> 1);
Jonathan Austin 1:8aa5cdb4ab67 312
Jonathan Austin 1:8aa5cdb4ab67 313 random_value = rnd;
Jonathan Austin 1:8aa5cdb4ab67 314
Jonathan Austin 1:8aa5cdb4ab67 315 result = ((result << 1) | (rnd & 0x00000001));
Jonathan Austin 1:8aa5cdb4ab67 316 } while(m >>= 1);
Jonathan Austin 1:8aa5cdb4ab67 317 } while (result > (uint32_t)max);
Jonathan Austin 1:8aa5cdb4ab67 318
Jonathan Austin 1:8aa5cdb4ab67 319 return result;
Jonathan Austin 1:8aa5cdb4ab67 320 }
Jonathan Austin 1:8aa5cdb4ab67 321
Jonathan Austin 1:8aa5cdb4ab67 322 /**
Jonathan Austin 1:8aa5cdb4ab67 323 * Seed the random number generator (RNG).
Jonathan Austin 1:8aa5cdb4ab67 324 *
Jonathan Austin 1:8aa5cdb4ab67 325 * This function uses the NRF51822's in built cryptographic random number generator to seed a Galois LFSR.
Jonathan Austin 1:8aa5cdb4ab67 326 * We do this as the hardware RNG is relatively high power, and is locked out by the BLE stack internally,
Jonathan Austin 1:8aa5cdb4ab67 327 * with a less than optimal application interface. A Galois LFSR is sufficient for our
Jonathan Austin 1:8aa5cdb4ab67 328 * applications, and much more lightweight.
Jonathan Austin 1:8aa5cdb4ab67 329 */
Jonathan Austin 1:8aa5cdb4ab67 330 void microbit_seed_random()
Jonathan Austin 1:8aa5cdb4ab67 331 {
Jonathan Austin 1:8aa5cdb4ab67 332 random_value = 0;
Jonathan Austin 1:8aa5cdb4ab67 333
Jonathan Austin 1:8aa5cdb4ab67 334 if(ble_running())
Jonathan Austin 1:8aa5cdb4ab67 335 {
Jonathan Austin 1:8aa5cdb4ab67 336 // If Bluetooth is enabled, we need to go through the Nordic software to safely do this.
Jonathan Austin 1:8aa5cdb4ab67 337 uint32_t result = sd_rand_application_vector_get((uint8_t*)&random_value, sizeof(random_value));
Jonathan Austin 1:8aa5cdb4ab67 338
Jonathan Austin 1:8aa5cdb4ab67 339 // If we couldn't get the random bytes then at least make the seed non-zero.
Jonathan Austin 1:8aa5cdb4ab67 340 if (result != NRF_SUCCESS)
Jonathan Austin 1:8aa5cdb4ab67 341 random_value = 0xBBC5EED;
Jonathan Austin 1:8aa5cdb4ab67 342 }
Jonathan Austin 1:8aa5cdb4ab67 343 else
Jonathan Austin 1:8aa5cdb4ab67 344 {
Jonathan Austin 1:8aa5cdb4ab67 345 // Othwerwise we can access the hardware RNG directly.
Jonathan Austin 1:8aa5cdb4ab67 346
Jonathan Austin 1:8aa5cdb4ab67 347 // Start the Random number generator. No need to leave it running... I hope. :-)
Jonathan Austin 1:8aa5cdb4ab67 348 NRF_RNG->TASKS_START = 1;
Jonathan Austin 1:8aa5cdb4ab67 349
Jonathan Austin 1:8aa5cdb4ab67 350 for(int i = 0; i < 4; i++)
Jonathan Austin 1:8aa5cdb4ab67 351 {
Jonathan Austin 1:8aa5cdb4ab67 352 // Clear the VALRDY EVENT
Jonathan Austin 1:8aa5cdb4ab67 353 NRF_RNG->EVENTS_VALRDY = 0;
Jonathan Austin 1:8aa5cdb4ab67 354
Jonathan Austin 1:8aa5cdb4ab67 355 // Wait for a number ot be generated.
Jonathan Austin 1:8aa5cdb4ab67 356 while(NRF_RNG->EVENTS_VALRDY == 0);
Jonathan Austin 1:8aa5cdb4ab67 357
Jonathan Austin 1:8aa5cdb4ab67 358 random_value = (random_value << 8) | ((int) NRF_RNG->VALUE);
Jonathan Austin 1:8aa5cdb4ab67 359 }
Jonathan Austin 1:8aa5cdb4ab67 360
Jonathan Austin 1:8aa5cdb4ab67 361 // Disable the generator to save power.
Jonathan Austin 1:8aa5cdb4ab67 362 NRF_RNG->TASKS_STOP = 1;
Jonathan Austin 1:8aa5cdb4ab67 363 }
Jonathan Austin 1:8aa5cdb4ab67 364 }
Jonathan Austin 1:8aa5cdb4ab67 365
Jonathan Austin 1:8aa5cdb4ab67 366 /**
Jonathan Austin 1:8aa5cdb4ab67 367 * Seed the pseudo random number generator (RNG) using the given 32-bit value.
Jonathan Austin 1:8aa5cdb4ab67 368 * This function does not use the NRF51822's in built cryptographic random number generator.
Jonathan Austin 1:8aa5cdb4ab67 369 *
Jonathan Austin 1:8aa5cdb4ab67 370 * @param seed The value to use as a seed.
Jonathan Austin 1:8aa5cdb4ab67 371 */
Jonathan Austin 1:8aa5cdb4ab67 372 void microbit_seed_random(uint32_t seed)
Jonathan Austin 1:8aa5cdb4ab67 373 {
Jonathan Austin 1:8aa5cdb4ab67 374 random_value = seed;
Jonathan Austin 1:8aa5cdb4ab67 375 }