src/lib/FHSS/FHSS.cpp

   1 #include "FHSS.h"
   2 #include "logging.h"
   3 #include <string.h>
   4
   5 // Our table of FHSS frequencies. Define a regulatory domain to select the correct set for your location and radio
   6 #ifdef Regulatory_Domain_AU_433
   7 const uint32_t FHSSfreqs[] = {
   8     FREQ_HZ_TO_REG_VAL(433420000),
   9     FREQ_HZ_TO_REG_VAL(433920000),
  10     FREQ_HZ_TO_REG_VAL(434420000)};
  11 #elif defined Regulatory_Domain_AU_915
  12 const uint32_t FHSSfreqs[] = {
  13     FREQ_HZ_TO_REG_VAL(915500000),
  14     FREQ_HZ_TO_REG_VAL(916100000),
  15     FREQ_HZ_TO_REG_VAL(916700000),
  16     FREQ_HZ_TO_REG_VAL(917300000),
  17
  18     FREQ_HZ_TO_REG_VAL(917900000),
  19     FREQ_HZ_TO_REG_VAL(918500000),
  20     FREQ_HZ_TO_REG_VAL(919100000),
  21     FREQ_HZ_TO_REG_VAL(919700000),
  22
  23     FREQ_HZ_TO_REG_VAL(920300000),
  24     FREQ_HZ_TO_REG_VAL(920900000),
  25     FREQ_HZ_TO_REG_VAL(921500000),
  26     FREQ_HZ_TO_REG_VAL(922100000),
  27
  28     FREQ_HZ_TO_REG_VAL(922700000),
  29     FREQ_HZ_TO_REG_VAL(923300000),
  30     FREQ_HZ_TO_REG_VAL(923900000),
  31     FREQ_HZ_TO_REG_VAL(924500000),
  32
  33     FREQ_HZ_TO_REG_VAL(925100000),
  34     FREQ_HZ_TO_REG_VAL(925700000),
  35     FREQ_HZ_TO_REG_VAL(926300000),
  36     FREQ_HZ_TO_REG_VAL(926900000)};
  37 #elif defined Regulatory_Domain_EU_868
  38 /* Frequency bands taken from https://wetten.overheid.nl/BWBR0036378/2016-12-28#Bijlagen
  39  * Note: these frequencies fall in the license free H-band, but in combination with 500kHz
  40  * LoRa modem bandwidth used by ExpressLRS (EU allows up to 125kHz modulation BW only) they
  41  * will never pass RED certification and they are ILLEGAL to use.
  42  *
  43  * Therefore we simply maximize the usage of available spectrum so laboratory testing of the software won't disturb existing
  44  * 868MHz ISM band traffic too much.
  45  */
  46 const uint32_t FHSSfreqs[] = {
  47     FREQ_HZ_TO_REG_VAL(863275000), // band H1, 863 - 865MHz, 0.1% duty cycle or CSMA techniques, 25mW EIRP
  48     FREQ_HZ_TO_REG_VAL(863800000),
  49     FREQ_HZ_TO_REG_VAL(864325000),
  50     FREQ_HZ_TO_REG_VAL(864850000),
  51     FREQ_HZ_TO_REG_VAL(865375000), // Band H2, 865 - 868.6MHz, 1.0% dutycycle or CSMA, 25mW EIRP
  52     FREQ_HZ_TO_REG_VAL(865900000),
  53     FREQ_HZ_TO_REG_VAL(866425000),
  54     FREQ_HZ_TO_REG_VAL(866950000),
  55     FREQ_HZ_TO_REG_VAL(867475000),
  56     FREQ_HZ_TO_REG_VAL(868000000),
  57     FREQ_HZ_TO_REG_VAL(868525000), // Band H3, 868.7-869.2MHz, 0.1% dutycycle or CSMA, 25mW EIRP
  58     FREQ_HZ_TO_REG_VAL(869050000),
  59     FREQ_HZ_TO_REG_VAL(869575000)};
  60 #elif defined Regulatory_Domain_IN_866
  61 /**
  62  * India currently delicensed the 865-867 MHz band with a maximum of 1W Transmitter power,
  63  * 4Watts Effective Radiated Power and 200Khz carrier bandwidth as per
  64  * https://dot.gov.in/sites/default/files/Delicensing%20in%20865-867%20MHz%20band%20%5BGSR%20564%20%28E%29%5D_0.pdf .
  65  * There is currently no mention of Direct-sequence spread spectrum,
  66  * So these frequencies are a subset of Regulatory_Domain_EU_868 frequencies.
  67  */
  68 const uint32_t FHSSfreqs[] = {
  69     FREQ_HZ_TO_REG_VAL(865375000),
  70     FREQ_HZ_TO_REG_VAL(865900000),
  71     FREQ_HZ_TO_REG_VAL(866425000),
  72     FREQ_HZ_TO_REG_VAL(866950000)};
  73 #elif defined Regulatory_Domain_EU_433
  74 /* Frequency band G, taken from https://wetten.overheid.nl/BWBR0036378/2016-12-28#Bijlagen
  75  * Note: As is the case with the 868Mhz band, these frequencies only comply to the license free portion
  76  * of the spectrum, nothing else. As such, these are likely illegal to use.
  77  */
  78 const uint32_t FHSSfreqs[] = {
  79     FREQ_HZ_TO_REG_VAL(433100000),
  80     FREQ_HZ_TO_REG_VAL(433925000),
  81     FREQ_HZ_TO_REG_VAL(434450000)};
  82 #elif defined Regulatory_Domain_FCC_915
  83 /* Very definitely not fully checked. An initial pass at increasing the hops
  84 */
  85 const uint32_t FHSSfreqs[] = {
  86     FREQ_HZ_TO_REG_VAL(903500000),
  87     FREQ_HZ_TO_REG_VAL(904100000),
  88     FREQ_HZ_TO_REG_VAL(904700000),
  89     FREQ_HZ_TO_REG_VAL(905300000),
  90
  91     FREQ_HZ_TO_REG_VAL(905900000),
  92     FREQ_HZ_TO_REG_VAL(906500000),
  93     FREQ_HZ_TO_REG_VAL(907100000),
  94     FREQ_HZ_TO_REG_VAL(907700000),
  95
  96     FREQ_HZ_TO_REG_VAL(908300000),
  97     FREQ_HZ_TO_REG_VAL(908900000),
  98     FREQ_HZ_TO_REG_VAL(909500000),
  99     FREQ_HZ_TO_REG_VAL(910100000),
 100
 101     FREQ_HZ_TO_REG_VAL(910700000),
 102     FREQ_HZ_TO_REG_VAL(911300000),
 103     FREQ_HZ_TO_REG_VAL(911900000),
 104     FREQ_HZ_TO_REG_VAL(912500000),
 105
 106     FREQ_HZ_TO_REG_VAL(913100000),
 107     FREQ_HZ_TO_REG_VAL(913700000),
 108     FREQ_HZ_TO_REG_VAL(914300000),
 109     FREQ_HZ_TO_REG_VAL(914900000),
 110
 111     FREQ_HZ_TO_REG_VAL(915500000), // as per AU..
 112     FREQ_HZ_TO_REG_VAL(916100000),
 113     FREQ_HZ_TO_REG_VAL(916700000),
 114     FREQ_HZ_TO_REG_VAL(917300000),
 115
 116     FREQ_HZ_TO_REG_VAL(917900000),
 117     FREQ_HZ_TO_REG_VAL(918500000),
 118     FREQ_HZ_TO_REG_VAL(919100000),
 119     FREQ_HZ_TO_REG_VAL(919700000),
 120
 121     FREQ_HZ_TO_REG_VAL(920300000),
 122     FREQ_HZ_TO_REG_VAL(920900000),
 123     FREQ_HZ_TO_REG_VAL(921500000),
 124     FREQ_HZ_TO_REG_VAL(922100000),
 125
 126     FREQ_HZ_TO_REG_VAL(922700000),
 127     FREQ_HZ_TO_REG_VAL(923300000),
 128     FREQ_HZ_TO_REG_VAL(923900000),
 129     FREQ_HZ_TO_REG_VAL(924500000),
 130
 131     FREQ_HZ_TO_REG_VAL(925100000),
 132     FREQ_HZ_TO_REG_VAL(925700000),
 133     FREQ_HZ_TO_REG_VAL(926300000),
 134     FREQ_HZ_TO_REG_VAL(926900000)};
 135 #elif Regulatory_Domain_ISM_2400
 136 const uint32_t FHSSfreqs[] = {
 137     FREQ_HZ_TO_REG_VAL(2400400000),
 138     FREQ_HZ_TO_REG_VAL(2401400000),
 139     FREQ_HZ_TO_REG_VAL(2402400000),
 140     FREQ_HZ_TO_REG_VAL(2403400000),
 141     FREQ_HZ_TO_REG_VAL(2404400000),
 142
 143     FREQ_HZ_TO_REG_VAL(2405400000),
 144     FREQ_HZ_TO_REG_VAL(2406400000),
 145     FREQ_HZ_TO_REG_VAL(2407400000),
 146     FREQ_HZ_TO_REG_VAL(2408400000),
 147     FREQ_HZ_TO_REG_VAL(2409400000),
 148
 149     FREQ_HZ_TO_REG_VAL(2410400000),
 150     FREQ_HZ_TO_REG_VAL(2411400000),
 151     FREQ_HZ_TO_REG_VAL(2412400000),
 152     FREQ_HZ_TO_REG_VAL(2413400000),
 153     FREQ_HZ_TO_REG_VAL(2414400000),
 154
 155     FREQ_HZ_TO_REG_VAL(2415400000),
 156     FREQ_HZ_TO_REG_VAL(2416400000),
 157     FREQ_HZ_TO_REG_VAL(2417400000),
 158     FREQ_HZ_TO_REG_VAL(2418400000),
 159     FREQ_HZ_TO_REG_VAL(2419400000),
 160
 161     FREQ_HZ_TO_REG_VAL(2420400000),
 162     FREQ_HZ_TO_REG_VAL(2421400000),
 163     FREQ_HZ_TO_REG_VAL(2422400000),
 164     FREQ_HZ_TO_REG_VAL(2423400000),
 165     FREQ_HZ_TO_REG_VAL(2424400000),
 166
 167     FREQ_HZ_TO_REG_VAL(2425400000),
 168     FREQ_HZ_TO_REG_VAL(2426400000),
 169     FREQ_HZ_TO_REG_VAL(2427400000),
 170     FREQ_HZ_TO_REG_VAL(2428400000),
 171     FREQ_HZ_TO_REG_VAL(2429400000),
 172
 173     FREQ_HZ_TO_REG_VAL(2430400000),
 174     FREQ_HZ_TO_REG_VAL(2431400000),
 175     FREQ_HZ_TO_REG_VAL(2432400000),
 176     FREQ_HZ_TO_REG_VAL(2433400000),
 177     FREQ_HZ_TO_REG_VAL(2434400000),
 178
 179     FREQ_HZ_TO_REG_VAL(2435400000),
 180     FREQ_HZ_TO_REG_VAL(2436400000),
 181     FREQ_HZ_TO_REG_VAL(2437400000),
 182     FREQ_HZ_TO_REG_VAL(2438400000),
 183     FREQ_HZ_TO_REG_VAL(2439400000),
 184
 185     FREQ_HZ_TO_REG_VAL(2440400000),
 186     FREQ_HZ_TO_REG_VAL(2441400000),
 187     FREQ_HZ_TO_REG_VAL(2442400000),
 188     FREQ_HZ_TO_REG_VAL(2443400000),
 189     FREQ_HZ_TO_REG_VAL(2444400000),
 190
 191     FREQ_HZ_TO_REG_VAL(2445400000),
 192     FREQ_HZ_TO_REG_VAL(2446400000),
 193     FREQ_HZ_TO_REG_VAL(2447400000),
 194     FREQ_HZ_TO_REG_VAL(2448400000),
 195     FREQ_HZ_TO_REG_VAL(2449400000),
 196
 197     FREQ_HZ_TO_REG_VAL(2450400000),
 198     FREQ_HZ_TO_REG_VAL(2451400000),
 199     FREQ_HZ_TO_REG_VAL(2452400000),
 200     FREQ_HZ_TO_REG_VAL(2453400000),
 201     FREQ_HZ_TO_REG_VAL(2454400000),
 202
 203     FREQ_HZ_TO_REG_VAL(2455400000),
 204     FREQ_HZ_TO_REG_VAL(2456400000),
 205     FREQ_HZ_TO_REG_VAL(2457400000),
 206     FREQ_HZ_TO_REG_VAL(2458400000),
 207     FREQ_HZ_TO_REG_VAL(2459400000),
 208
 209     FREQ_HZ_TO_REG_VAL(2460400000),
 210     FREQ_HZ_TO_REG_VAL(2461400000),
 211     FREQ_HZ_TO_REG_VAL(2462400000),
 212     FREQ_HZ_TO_REG_VAL(2463400000),
 213     FREQ_HZ_TO_REG_VAL(2464400000),
 214
 215     FREQ_HZ_TO_REG_VAL(2465400000),
 216     FREQ_HZ_TO_REG_VAL(2466400000),
 217     FREQ_HZ_TO_REG_VAL(2467400000),
 218     FREQ_HZ_TO_REG_VAL(2468400000),
 219     FREQ_HZ_TO_REG_VAL(2469400000),
 220
 221     FREQ_HZ_TO_REG_VAL(2470400000),
 222     FREQ_HZ_TO_REG_VAL(2471400000),
 223     FREQ_HZ_TO_REG_VAL(2472400000),
 224     FREQ_HZ_TO_REG_VAL(2473400000),
 225     FREQ_HZ_TO_REG_VAL(2474400000),
 226
 227     FREQ_HZ_TO_REG_VAL(2475400000),
 228     FREQ_HZ_TO_REG_VAL(2476400000),
 229     FREQ_HZ_TO_REG_VAL(2477400000),
 230     FREQ_HZ_TO_REG_VAL(2478400000),
 231     FREQ_HZ_TO_REG_VAL(2479400000)};
 232 #else
 233 #error No regulatory domain defined, please define one in user_defines.txt
 234 #endif
 235
 236 // Number of FHSS frequencies in the table
 237 constexpr uint32_t FHSS_FREQ_CNT = (sizeof(FHSSfreqs) / sizeof(uint32_t));
 238 // Number of hops in the FHSSsequence list before circling back around, even multiple of the number of frequencies
 239 constexpr uint8_t  FHSS_SEQUENCE_CNT = (256 / FHSS_FREQ_CNT) * FHSS_FREQ_CNT;
 240 // Actual sequence of hops as indexes into the frequency list
 241 uint8_t FHSSsequence[FHSS_SEQUENCE_CNT];
 242 // Which entry in the sequence we currently are on
 243 uint8_t volatile FHSSptr;
 244 // Channel for sync packets and initial connection establishment
 245 uint_fast8_t sync_channel;
 246 // Offset from the predefined frequency determined by AFC on Team900 (register units)
 247 int32_t FreqCorrection;
 248
 249 /**
 250 Requirements:
 251 1. 0 every n hops
 252 2. No two repeated channels
 253 3. Equal occurance of each (or as even as possible) of each channel
 254 4. Pseudorandom
 255
 256 Approach:
 257   Fill the sequence array with the sync channel every FHSS_FREQ_CNT
 258   Iterate through the array, and for each block, swap each entry in it with
 259   another random entry, excluding the sync channel.
 260
 261 */
 262 void FHSSrandomiseFHSSsequence(const uint32_t seed)
 263 {
 264 #ifdef Regulatory_Domain_AU_915
 265     INFOLN("Setting 915MHz AU Mode");
 266 #elif defined Regulatory_Domain_FCC_915
 267     INFOLN("Setting 915MHz FCC Mode");
 268 #elif defined Regulatory_Domain_EU_868
 269     INFOLN("Setting 868MHz EU Mode");
 270 #elif defined Regulatory_Domain_IN_866
 271     INFOLN("Setting 866MHz IN Mode");
 272 #elif defined Regulatory_Domain_AU_433
 273     INFOLN("Setting 433MHz AU Mode");
 274 #elif defined Regulatory_Domain_EU_433
 275     INFOLN("Setting 433MHz EU Mode");
 276 #elif defined Regulatory_Domain_ISM_2400
 277     INFOLN("Setting 2400MHz Mode");
 278 #else
 279 #error No regulatory domain defined, please define one in common.h
 280 #endif
 281
 282     DBGLN("Number of FHSS frequencies = %u", FHSS_FREQ_CNT);
 283
 284     sync_channel = FHSS_FREQ_CNT / 2;
 285     DBGLN("Sync channel = %u", sync_channel);
 286
 287     // reset the pointer (otherwise the tests fail)
 288     FHSSptr = 0;
 289     rngSeed(seed);
 290
 291     // initialize the sequence array
 292     for (uint8_t i = 0; i < FHSS_SEQUENCE_CNT; i++)
 293     {
 294         if (i % FHSS_FREQ_CNT == 0) {
 295             FHSSsequence[i] = sync_channel;
 296         } else if (i % FHSS_FREQ_CNT == sync_channel) {
 297             FHSSsequence[i] = 0;
 298         } else {
 299             FHSSsequence[i] = i % FHSS_FREQ_CNT;
 300         }
 301     }
 302
 303     for (uint8_t i=0; i < FHSS_SEQUENCE_CNT; i++)
 304     {
 305         // if it's not the sync channel
 306         if (i % FHSS_FREQ_CNT != 0)
 307         {
 308             uint8_t offset = (i / FHSS_FREQ_CNT) * FHSS_FREQ_CNT; // offset to start of current block
 309             uint8_t rand = rngN(FHSS_FREQ_CNT-1)+1; // random number between 1 and FHSS_FREQ_CNT
 310
 311             // switch this entry and another random entry in the same block
 312             uint8_t temp = FHSSsequence[i];
 313             FHSSsequence[i] = FHSSsequence[offset+rand];
 314             FHSSsequence[offset+rand] = temp;
 315         }
 316     }
 317
 318     // output FHSS sequence
 319     for (uint8_t i=0; i < FHSS_SEQUENCE_CNT; i++)
 320     {
 321         DBG("%u ",FHSSsequence[i]);
 322         if (i % 10 == 9)
 323             DBGCR;
 324     }
 325     DBGCR;
 326 }
 327
 328 uint32_t FHSSgetChannelCount(void)
 329 {
 330     return FHSS_FREQ_CNT;
 331 }