src/lib/FHSS/FHSS.cpp

   1 #include "FHSS.h"
   2 #include "logging.h"
   3 #include "options.h"
   4 #include <string.h>
   5
   6 #if defined(RADIO_SX127X)
   7 #include "SX127xDriver.h"
   8
   9 const fhss_config_t domains[] = {
  10     {"AU915",  FREQ_HZ_TO_REG_VAL(915500000), FREQ_HZ_TO_REG_VAL(926900000), 20},
  11     {"FCC915", FREQ_HZ_TO_REG_VAL(903500000), FREQ_HZ_TO_REG_VAL(926900000), 40},
  12     {"EU868",  FREQ_HZ_TO_REG_VAL(865275000), FREQ_HZ_TO_REG_VAL(869575000), 13},
  13     {"IN866",  FREQ_HZ_TO_REG_VAL(865375000), FREQ_HZ_TO_REG_VAL(866950000), 4},
  14     {"AU433",  FREQ_HZ_TO_REG_VAL(433420000), FREQ_HZ_TO_REG_VAL(434420000), 3},
  15     {"EU433",  FREQ_HZ_TO_REG_VAL(433100000), FREQ_HZ_TO_REG_VAL(434450000), 3}
  16 };
  17 #elif defined(RADIO_SX128X)
  18 #include "SX1280Driver.h"
  19
  20 const fhss_config_t domains[] = {
  21     {
  22     #if defined(Regulatory_Domain_EU_CE_2400)
  23         "CE_LBT",
  24     #elif defined(Regulatory_Domain_ISM_2400)
  25         "ISM2G4",
  26     #endif
  27     FREQ_HZ_TO_REG_VAL(2400400000), FREQ_HZ_TO_REG_VAL(2479400000), 80}
  28 };
  29 #endif
  30
  31 // Our table of FHSS frequencies. Define a regulatory domain to select the correct set for your location and radio
  32 const fhss_config_t *FHSSconfig;
  33
  34 // Actual sequence of hops as indexes into the frequency list
  35 uint8_t FHSSsequence[256];
  36 // Which entry in the sequence we currently are on
  37 uint8_t volatile FHSSptr;
  38 // Channel for sync packets and initial connection establishment
  39 uint_fast8_t sync_channel;
  40 // Offset from the predefined frequency determined by AFC on Team900 (register units)
  41 int32_t FreqCorrection;
  42 int32_t FreqCorrection_2;
  43
  44 uint32_t freq_spread;
  45
  46 /**
  47 Requirements:
  48 1. 0 every n hops
  49 2. No two repeated channels
  50 3. Equal occurance of each (or as even as possible) of each channel
  51 4. Pseudorandom
  52
  53 Approach:
  54   Fill the sequence array with the sync channel every FHSS_FREQ_CNT
  55   Iterate through the array, and for each block, swap each entry in it with
  56   another random entry, excluding the sync channel.
  57
  58 */
  59 void FHSSrandomiseFHSSsequence(const uint32_t seed)
  60 {
  61     FHSSconfig = &domains[firmwareOptions.domain];
  62     INFOLN("Setting %s Mode", FHSSconfig->domain);
  63     DBGLN("Number of FHSS frequencies = %u", FHSSconfig->freq_count);
  64
  65     sync_channel = (FHSSconfig->freq_count / 2) + 1;
  66     DBGLN("Sync channel = %u", sync_channel);
  67
  68     freq_spread = (FHSSconfig->freq_stop - FHSSconfig->freq_start) * FREQ_SPREAD_SCALE / (FHSSconfig->freq_count - 1);
  69
  70     // reset the pointer (otherwise the tests fail)
  71     FHSSptr = 0;
  72     rngSeed(seed);
  73
  74     // initialize the sequence array
  75     for (uint16_t i = 0; i < FHSSgetSequenceCount(); i++)
  76     {
  77         if (i % FHSSconfig->freq_count == 0) {
  78             FHSSsequence[i] = sync_channel;
  79         } else if (i % FHSSconfig->freq_count == sync_channel) {
  80             FHSSsequence[i] = 0;
  81         } else {
  82             FHSSsequence[i] = i % FHSSconfig->freq_count;
  83         }
  84     }
  85
  86     for (uint16_t i=0; i < FHSSgetSequenceCount(); i++)
  87     {
  88         // if it's not the sync channel
  89         if (i % FHSSconfig->freq_count != 0)
  90         {
  91             uint8_t offset = (i / FHSSconfig->freq_count) * FHSSconfig->freq_count; // offset to start of current block
  92             uint8_t rand = rngN(FHSSconfig->freq_count-1)+1; // random number between 1 and FHSS_FREQ_CNT
  93
  94             // switch this entry and another random entry in the same block
  95             uint8_t temp = FHSSsequence[i];
  96             FHSSsequence[i] = FHSSsequence[offset+rand];
  97             FHSSsequence[offset+rand] = temp;
  98         }
  99     }
 100
 101     // output FHSS sequence
 102     for (uint16_t i=0; i < FHSSgetSequenceCount(); i++)
 103     {
 104         DBG("%u ",FHSSsequence[i]);
 105         if (i % 10 == 9)
 106             DBGCR;
 107     }
 108     DBGCR;
 109 }
 110
 111 bool isDomain868()
 112 {
 113     return strcmp(FHSSconfig->domain, "EU868") == 0;
 114 }