Add support for Schou 72543 rain sensor (#2686)

README.md

@@ -335,6 +335,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
     [247]  Bresser water leakage
     [248]* Nissan TPMS
     [249]  Bresser lightning
+    [250]  Schou 72543 Day Rain Gauge
 
 * Disabled by default, use -R n or a conf file to enable
 

conf/rtl_433.example.conf

@@ -399,7 +399,7 @@ convert si
   protocol 170 # LaCrosse Technology View LTV-WR1 Multi Sensor
   protocol 171 # LaCrosse Technology View LTV-TH Thermo/Hygro Sensor
   protocol 172 # Bresser Weather Center 6-in-1, 7-in-1 indoor, soil, new 5-in-1, 3-in-1 wind gauge, Froggit WH6000, Ventus C8488A
-  protocol 173 # Bresser Weather Center 7-in-1
+  protocol 173 # Bresser Weather Center 7-in-1, Air Quality PM2.5 / PM10
   protocol 174 # EcoDHOME Smart Socket and MCEE Solar monitor
   protocol 175 # LaCrosse Technology View LTV-R1, LTV-R3 Rainfall Gauge, LTV-W1/W2 Wind Sensor
   protocol 176 # BlueLine Innovations Power Cost Monitor
@@ -476,6 +476,7 @@ convert si
   protocol 247 # Bresser water leakage
 # protocol 248 # Nissan TPMS
   protocol 249 # Bresser lightning
+  protocol 250 # Schou 72543 Day Rain Gauge
 
 ## Flex devices (command line option "-X")
 

include/rtl_433_devices.h

@@ -257,6 +257,7 @@
     DECL(bresser_leakage) \
     DECL(tpms_nissan) \
     DECL(bresser_lightning) \
+    DECL(schou_72543_rain) \
 
     /* Add new decoders here. */
 

src/CMakeLists.txt

@@ -201,6 +201,7 @@ add_library(r_433 STATIC
     devices/rubicson_48659.c
     devices/rubicson_pool_48942.c
     devices/s3318p.c
+    devices/schou_72543_rain.c
     devices/schraeder.c
     devices/scmplus.c
     devices/secplus_v1.c

src/devices/schou_72543_rain.c

@@ -0,0 +1,120 @@
+/** @file
+    Schou 72543 Day Rain Gauge.
+
+    contributed by Jesper M. Nielsen
+    discovered by Jesper M. Nielsen
+    based upon ambient_weather.c
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+*/
+
+#include "decoder.h"
+
+/**
+Decode Schou 72543 Rain Gauge, DAY series.
+
+Devices supported:
+
+- Schou 72543 Rain Gauge, DAY Series.
+
+This decoder handles the 433mhz rain-thermometer.
+
+Codes example: {66}50fc467b7f9a832a8, {65}a1f88cf6ff3506550, {70}a1f88cf6ff3506557c
+
+    {66}: [ 0 ] [ 1010 0001 1111 1000 ] [ 1000 ] [ 1100 ] [ 1111 0110 ] [ 1111 1111 ] [ 0011 0101 ] [ 0000 0110 ] [ 0101 0101 ] [ 0       ]
+    {65}:       [ 1010 0001 1111 1000 ] [ 1000 ] [ 1100 ] [ 1111 0110 ] [ 1111 1111 ] [ 0011 0101 ] [ 0000 0110 ] [ 0101 0101 ] [ 0       ]
+    {70}:       [ 1010 0001 1111 1000 ] [ 1000 ] [ 1100 ] [ 1111 0110 ] [ 1111 1111 ] [ 0011 0101 ] [ 0000 0110 ] [ 0101 0101 ] [ 0111 11 ]
+    KEY:  [ 0 ] [ IIII IIII IIII IIII ] [ SSSS ] [ NNNN ] [ rrrr rrrr ] [ RRRR RRRR ] [ tttt tttt ] [ TTTT TTTT ] [ CCCC CCCC ] [ 0??? ?? ]
+
+- 0:  Always zero
+- ?:  Either 1 or 0
+- I:  16 bit random ID. Resets to new value after every battery change
+- S:  Status bits
+      [ X--- ]: Battery status:  0: OK,  1: Low battery
+      [ -X-- ]: Repeated signal: 0: New, 1: Repeat of last message (4 repeats will happen after battery replacement)
+      [ --XX ]: Assumed always to be 0
+- N:  4 bit running count. Increased by 2 every value incremented by 2 every message, i.e. 0, 2, 4, 6, 8, a, c, e, 0, 2...
+- Rr: 16 bit Rainfall in 1/10 millimeters per count. Initial value fff6 = 6552.6 mm rain
+      r: lower 8 bit, initializes to f6
+      R: Upper 8 bit, initializes to ff
+- Tt: 16 bit temperature.
+      t: lower 8 bit
+      T: Upper 8 bit
+- C:  Checksum. Running 8 bit sum of the data left of the checksum.
+      E.g. {65}a1f88cf6ff3506'55'0 Checksum is 55 obtained as ( a1 + f8 + 8c + f6 + ff + 35 + 06 ) = 455 i.e. 55
+
+*/
+
+static int schou_72543_rain_decode(r_device *decoder, bitbuffer_t *bitbuffer)
+{
+    // Full data is 3 rows, two are required for data validation
+    if (bitbuffer->num_rows < 2) {
+        return DECODE_ABORT_LENGTH;
+    }
+
+    // Check if the first 64 bits of at least two rows are alike
+    int row = bitbuffer_find_repeated_prefix(bitbuffer, 2, 64);
+    if (row < 0) {
+        return DECODE_ABORT_EARLY;
+    }
+
+    // Load bitbuffer data and validate checksum
+    uint8_t *b  = bitbuffer->bb[row];
+    int micsum = b[7];                    // Checksum as read
+    int calsum = add_bytes(b, 7) & 0x0FF; // Checksum as calculated, accounting for the lowest 8 bit
+
+    if (micsum != calsum) {
+        decoder_logf_bitrow(decoder, 1, __func__, b, 65, "Checksum error, expected: %02x calculated: %02x", micsum, calsum);
+        return DECODE_FAIL_MIC;
+    }
+
+    // Decode message
+    int device_id       = (b[0] << 8) | b[1];                  // Assuming little endian, but it not important as the value is random
+    int battery_low     = (b[2] & 0x80) > 0;                   // if one, battery is low
+    int message_repeat  = (b[2] & 0x40) > 0;                   // if one, message is a repeat (startup after batteries are replaced)
+    int message_counter = (b[2] & 0x0e) >> 1;                  // 3 bit counter (rather than 4 bit incrementing by 2 each time
+    float rain_mm       = ((b[4] << 8) | b[3]) * 0.1f;         //   0.0 to  6553.5  mm
+    float temperature_F = (((b[6] << 8) | b[5]) - 900) * 0.1f; // -40.0 to +158     degF
+
+    /* clang-format off */
+    data_t   *data = data_make(
+            "model",            "",             DATA_STRING, "Schou-72543",
+            "id",               "ID",           DATA_INT,    device_id,
+            "temperature_F",    "Temperature",  DATA_FORMAT, "%.1f F",  DATA_DOUBLE, temperature_F,
+            "rain_mm",          "Rain",         DATA_FORMAT, "%.1f mm", DATA_DOUBLE, rain_mm,
+            "battery_ok",       "Battery_ok",   DATA_INT,    !battery_low,
+            "msg_counter",      "Counter",      DATA_INT,    message_counter,
+            "msg_repeat",       "Msg_repeat",   DATA_INT,    message_repeat,
+            "mic",              "Integrity",    DATA_STRING, "CHECKSUM",
+            NULL);
+    /* clang-format on */
+
+    decoder_output_data(decoder, data);
+    return 1;
+}
+
+static char const *const output_fields[] = {
+        "model",
+        "id",
+        "temperature_F",
+        "rain_mm",
+        "battery_ok",
+        "msg_counter",
+        "msg_repeat",
+        "mic",
+        NULL,
+};
+
+r_device const schou_72543_rain = {
+        .name        = "Schou 72543 Day Rain Gauge",
+        .modulation  = OOK_PULSE_PWM,
+        .short_width = 972,
+        .long_width  = 2680,
+        .sync_width  = 7328,
+        .reset_limit = 2712,
+        .decode_fn   = &schou_72543_rain_decode,
+        .fields      = output_fields,
+};