src/devices/oil_watchman.c

   1 /* Oil tank monitor using Si4320 framed FSK protocol
   2  *
   3  * Tested devices:
   4  * Sensor Systems Watchman Sonic
   5  *
   6  * Copyright © 2015 David Woodhouse
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  */
  13 #include "rtl_433.h"
  14 #include "pulse_demod.h"
  15 #include "util.h"
  16
  17
  18 // Start of frame preamble is 111000xx
  19 static const unsigned char preamble_pattern = 0xe0;
  20
  21 // End of frame is 00xxxxxx or 11xxxxxx depending on final data bit
  22 static const unsigned char postamble_pattern[2] = { 0x00, 0xc0 };
  23
  24 static int oil_watchman_callback(bitbuffer_t *bitbuffer) {
  25         uint8_t *b;
  26         uint32_t unit_id;
  27         uint16_t depth = 0;
  28         uint16_t binding_countdown = 0;
  29         uint8_t flags;
  30         uint8_t maybetemp;
  31         double temperature;
  32         char time_str[LOCAL_TIME_BUFLEN];
  33         data_t *data;
  34         unsigned bitpos = 0;
  35         bitbuffer_t databits = {0};
  36         int events = 0;
  37
  38         local_time_str(0, time_str);
  39
  40         // Find a preamble with enough bits after it that it could be a complete packet
  41         while ((bitpos = bitbuffer_search(bitbuffer, 0, bitpos, &preamble_pattern, 6)) + 136 <=
  42                bitbuffer->bits_per_row[0]) {
  43
  44                 // Skip the matched preamble bits to point to the data
  45                 bitpos += 6;
  46
  47                 bitpos = bitbuffer_manchester_decode(bitbuffer, 0, bitpos, &databits, 64);
  48                 if (databits.bits_per_row[0] != 64)
  49                         continue;
  50
  51                 b = databits.bb[0];
  52
  53                 // Check for postamble, depending on last data bit
  54                 if (bitbuffer_search(bitbuffer, 0, bitpos, &postamble_pattern[b[7] & 1], 2) != bitpos)
  55                         continue;
  56
  57                 if (b[7] != crc8le(b, 7, 0x31, 0))
  58                         continue;
  59
  60                 // The unit ID changes when you rebind by holding a magnet to the
  61                 // sensor for long enough; it seems to be time-based.
  62                 unit_id = (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
  63
  64                 // 0x01: Rebinding (magnet held to sensor)
  65                 // 0x08: Leak/theft alarm
  66                 // top three bits seem also to vary with temperature (independently of maybetemp)
  67                 flags = b[4];
  68
  69                 // Not entirely sure what this is but it might be inversely
  70                 // proportional to temperature.
  71                 maybetemp = b[5] >> 2;
  72                 temperature = (double)(145.0 - 5.0 * maybetemp) / 3.0;
  73                 if (flags & 1)
  74                         // When binding, the countdown counts up from 0x51 to 0x5a
  75                         // (as long as you hold the magnet to it for long enough)
  76                         // before the device ID changes. The receiver unit needs
  77                         // to receive this *strongly* in order to change its
  78                         // allegiance.
  79                         binding_countdown = b[6];
  80                 else
  81                         // A depth reading of zero indicates no reading. Even with
  82                         // the sensor flat down on a table, it still reads about 13.
  83                         depth = ((b[5] & 3) << 8) | b[6];
  84
  85                 data = data_make("time", "", DATA_STRING, time_str,
  86                                  "model", "", DATA_STRING, "Oil Watchman",
  87                                  "id", "", DATA_FORMAT, "%06x", DATA_INT, unit_id,
  88                                  "flags", "", DATA_FORMAT, "%02x", DATA_INT, flags,
  89                                  "maybetemp", "", DATA_INT, maybetemp,
  90                                  "temperature_C", "", DATA_DOUBLE, temperature,
  91                                  "binding_countdown", "", DATA_INT, binding_countdown,
  92                                  "depth", "", DATA_INT, depth,
  93                                  NULL);
  94                 data_acquired_handler(data);
  95                 events++;
  96         }
  97         return events;
  98 };
  99
 100 static char *output_fields[] = {
 101         "time",
 102         "model",
 103         "id",
 104         "flags",
 105         "maybetemp",
 106         "temperature_C",
 107         "binding_countdown",
 108         "depth",
 109         NULL
 110 };
 111
 112 r_device oil_watchman = {
 113         .name                   = "Watchman Sonic / Apollo Ultrasonic / Beckett Rocket oil tank monitor",
 114         .modulation             = FSK_PULSE_PCM,
 115         .short_limit    = 1000,
 116         .long_limit     = 1000, // NRZ
 117         .reset_limit    = 4000,
 118         .json_callback  = &oil_watchman_callback,
 119         .disabled               = 0,
 120         .fields                 = output_fields,
 121 };