src/devices/oregon_scientific_sl109h.c

   1 //some hints from http://www.osengr.org/WxShield/Downloads/OregonScientific-RF-Protocols-II.pdf
   2
   3 #include "rtl_433.h"
   4 #include "util.h"
   5
   6 #define SL109H_MESSAGE_LENGTH 38
   7 #define CHECKSUM_BYTE_COUNT 4
   8 #define CHECKSUM_START_POSITION 6
   9 #define HUMIDITY_START_POSITION 6
  10 #define HUMIDITY_BIT_COUNT 8
  11 #define TEMPERATURE_START_POSITION 14
  12 #define TEMPERATURE_BIT_COUNT 12
  13 #define ID_START_POSITION 30
  14
  15 static uint8_t calculate_humidity(bitbuffer_t *bitbuffer, unsigned row_index)
  16 {
  17     int units_digit, tens_digit;
  18
  19     uint8_t out[1] = {0};
  20     bitbuffer_extract_bytes(bitbuffer, row_index, HUMIDITY_START_POSITION, out, HUMIDITY_BIT_COUNT);
  21
  22     units_digit = out[0] & 0x0f;
  23
  24     tens_digit = (out[0] & 0xf0) >> 4;
  25
  26     return 10 * tens_digit + units_digit;
  27 }
  28
  29 static int calculate_centigrade_decidegrees(bitbuffer_t *bitbuffer, unsigned row_index)
  30 {
  31     int decidegrees = 0;
  32
  33     uint8_t out[2] = {0};
  34     bitbuffer_extract_bytes(bitbuffer, row_index, TEMPERATURE_START_POSITION, out, TEMPERATURE_BIT_COUNT);
  35
  36     if(out[0] & 0x80) decidegrees = (~decidegrees << TEMPERATURE_BIT_COUNT);
  37
  38     decidegrees |= (out[0] << 4) | ((out[1] & 0xf0) >> 4);
  39
  40     return decidegrees;
  41 }
  42
  43 static uint8_t get_channel_bits(uint8_t first_byte)
  44 {
  45     return (first_byte & 0x0c) >> 2;
  46 }
  47 static int calculate_channel(uint8_t channel_bits)
  48 {
  49     return (channel_bits % 3) ? channel_bits : 3;
  50 }
  51
  52 //rolling code: changes when thermometer reset button is pushed/battery is changed
  53 static uint8_t get_id(bitbuffer_t *bitbuffer, unsigned row_index)
  54 {
  55     uint8_t out[1] = {0};
  56     bitbuffer_extract_bytes(bitbuffer, row_index, ID_START_POSITION, out, SL109H_MESSAGE_LENGTH - ID_START_POSITION);
  57
  58     return out[0];
  59 }
  60
  61 //there may be more specific information here; not currently certain what information is encoded here
  62 static int get_status(uint8_t fourth_byte)
  63 {
  64     return (fourth_byte & 0x3C) >> 2;
  65 }
  66
  67 static int calculate_checksum(bitbuffer_t *bitbuffer, unsigned row_index, int channel)
  68 {
  69     uint8_t calculated_checksum, actual_checksum;
  70     uint8_t sum = 0;
  71     int  actual_expected_comparison;
  72
  73     uint8_t out[CHECKSUM_BYTE_COUNT] = {0};
  74     bitbuffer_extract_bytes(bitbuffer, row_index, CHECKSUM_START_POSITION, out, SL109H_MESSAGE_LENGTH - CHECKSUM_START_POSITION);
  75
  76     for(int i = 0; i < CHECKSUM_BYTE_COUNT; i++) sum += (out[i] & 0x0f) + (out[i] >> 4);
  77
  78     calculated_checksum = ((sum + channel) % 16);
  79     actual_checksum     = bitbuffer->bb[row_index][0] >> 4;
  80     actual_expected_comparison = (calculated_checksum == actual_checksum);
  81
  82     if(debug_output & !actual_expected_comparison) {
  83         fprintf(stderr, "Checksum error in Oregon Scientific SL109H message.  Expected: %01x  Calculated: %01x\n", actual_checksum, calculated_checksum);
  84         fprintf(stderr, "Message: ");
  85         bitbuffer_print(bitbuffer);
  86     }
  87
  88     return actual_expected_comparison;
  89 }
  90
  91
  92 static int oregon_scientific_callback_sl109h(bitbuffer_t *bitbuffer)
  93 {
  94     data_t *data;
  95     uint8_t *msg;
  96     uint8_t channel_bits;
  97
  98     float temp_c;
  99     uint8_t humidity;
 100     int channel;
 101     uint8_t id;
 102     int status;
 103     char time_str[LOCAL_TIME_BUFLEN];
 104
 105     for(int row_index = 0; row_index < bitbuffer->num_rows; row_index++) {
 106         msg = bitbuffer->bb[row_index];
 107
 108         channel_bits = get_channel_bits(msg[0]);
 109
 110         if( !((bitbuffer->bits_per_row[row_index] == SL109H_MESSAGE_LENGTH)
 111               && calculate_checksum(bitbuffer, row_index, channel_bits)) ) continue;
 112
 113         local_time_str(0, time_str);
 114
 115         temp_c = calculate_centigrade_decidegrees(bitbuffer, row_index) / 10.0;
 116
 117         humidity = calculate_humidity(bitbuffer, row_index);
 118
 119         id = get_id(bitbuffer, row_index);
 120
 121         channel = calculate_channel(channel_bits);
 122
 123         status = get_status(msg[3]);
 124
 125         data = data_make("time",          "",           DATA_STRING,                         time_str,
 126                          "temperature_C", "Celcius",    DATA_FORMAT, "%.02f C", DATA_DOUBLE, temp_c,
 127                          "humidity",      "Humidity",   DATA_FORMAT, "%u %%",   DATA_INT,    humidity,
 128                          "channel",       "Channel",                            DATA_INT,    channel,
 129                          "id",            "Id",                                 DATA_INT,    id,
 130                          "status",        "Status",                             DATA_INT,    status,
 131                          NULL);
 132         data_acquired_handler(data);
 133         return 1;
 134     }
 135
 136     return 0;
 137 }
 138
 139 static char *output_fields[] = {
 140     "time",
 141     "id",
 142     "channel",
 143     "status",
 144     "temperature_C",
 145     "humidity",
 146     NULL
 147 };
 148
 149 r_device oregon_scientific_sl109h = {
 150     .name           = "Oregon Scientific SL109H Remote Thermal Hygro Sensor",
 151     .modulation     = OOK_PULSE_PPM_RAW,
 152     .short_limit    = 2800/*760*/,
 153     .long_limit     = 4400/*1050*/,
 154     .reset_limit    = 8000/*2240*/,
 155     .json_callback  = &oregon_scientific_callback_sl109h,
 156     .disabled       = 0,
 157     .demod_arg      = 0,
 158     .fields         = output_fields
 159 };