Add support for Fine Offset WH45 air quality sensor

include/rtl_433_devices.h

@@ -226,6 +226,7 @@
     DECL(ant_antplus) \
     DECL(emos_e6016_rain) \
     DECL(hcs200_fsk) \
+    DECL(fineoffset_wh45) \
 
     /* Add new decoders here. */
 

src/CMakeLists.txt

@@ -101,6 +101,7 @@ add_library(r_433 STATIC
     devices/fineoffset_wh1050.c
     devices/fineoffset_wh1080.c
     devices/fineoffset_wh31l.c
+    devices/fineoffset_wh45.c
     devices/fineoffset_ws80.c
     devices/flex.c
     devices/fordremote.c

src/devices/fineoffset_wh45.c

@@ -0,0 +1,153 @@
+/** @file
+    Fine Offset Electronics WH45 air quality sensor.
+
+    Copyright (C) 2022 @anthyz
+
+    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"
+
+/**
+Fine Offset Electronics WH45 air quality sensor,
+
+- also Ecowitt WH45, Ecowitt WH0295
+- also Froggit DP250
+- also Ambient Weather AQIN
+
+Preamble is aaaa aaaa, sync word is 2dd4.
+
+Packet layout:
+
+     0  1  2  3  4  5  6  7  8  9 10 11 12 13 14
+    YY II II II 0T TT HH Bp pp BP PP CC CC XX AA
+    45 00 36 60 02 7e 36 40 23 00 29 02 29 07 4f
+
+- Y: 8 bit fixed sensor type 0x45
+- I: 24 bit device ID
+- T: 11 bit temperature, offset 40, scale 10
+- H: 8 bit humidity
+- B: 1 bit MSB of battery bars out of 5 (a value of 6 indicates external power via USB)
+- p: 14 bit PM2.5 reading in ug/m3 * 10
+- B: 2 bits LSBs of battery bars out of 5
+- P: 14 bit PM10 reading in ug/m3 * 10
+- C: 16 bit CO2 reading in ppm
+- X: 8 bit CRC
+- A: 8 bit checksum
+
+Older air quality sensors (WH0290/WH41/WH43) from Fine Offset use a
+particulate sensor from Honeywell that crudely estimates PM10 values
+from PM2.5 measurements. Though Ecowitt and other displays only show
+PM2.5, the rtl_433 WH0290 decoder includes the estimated PM10 value.
+See the WH0290 decoder for more details.
+
+The WH45 uses a Sensirion SPS30 sensor for PM2.5/PM10 and a
+Sensirion SCD30 for CO2.
+
+Technical documents for the SPS30 are here:
+
+https://sensirion.com/products/catalog/SPS30
+
+The sensor specification statement states that PM10 values are estimated
+from distribution profiles of PM0.5, PM1.0, and PM2.5 measurements, but
+the datasheet does a specify a degree of accuracy for the values unlike
+the Honeywell sensor.
+
+Technical documents for the SCD30 are here:
+
+https://sensirion.com/products/catalog/SCD30/
+*/
+
+static int fineoffset_wh45_decode(r_device *decoder, bitbuffer_t *bitbuffer)
+{
+    uint8_t const preamble[] = {0xaa, 0x2d, 0xd4}; // 24 bit, part of preamble and sync word
+    uint8_t b[15];
+
+    // bit counts have been observed between 187 and 222
+    if (bitbuffer->bits_per_row[0] < 170 || bitbuffer->bits_per_row[0] > 240) {
+        return DECODE_ABORT_LENGTH;
+    }
+
+    // Find a data package and extract data buffer
+    unsigned bit_offset = bitbuffer_search(bitbuffer, 0, 0, preamble, 24) + 24;
+    if (bit_offset + sizeof(b) * 8 > bitbuffer->bits_per_row[0]) { // Did not find a big enough package
+        decoder_logf_bitbuffer(decoder, 2, __func__, bitbuffer, "short package at %u", bit_offset);
+        return DECODE_ABORT_LENGTH;
+    }
+
+    // Extract package data
+    bitbuffer_extract_bytes(bitbuffer, 0, bit_offset, b, sizeof(b) * 8);
+
+    if (b[0] != 0x45) // Check for family code 0x45
+        return DECODE_ABORT_EARLY;
+
+    decoder_log_bitrow(decoder, 1, __func__, b, sizeof (b) * 8, "");
+
+    // Verify checksum and CRC
+    uint8_t crc = crc8(b, 13, 0x31, 0x00);
+    uint8_t chk = add_bytes(b, 14);
+    if (crc != b[13] || chk != b[14]) {
+        decoder_logf(decoder, 1, __func__, "Checksum error: %02x %02x", crc, chk);
+        return DECODE_FAIL_MIC;
+    }
+
+    int id            = (b[1] << 16) | (b[2] << 8) | (b[3]);
+    int temp_raw      = (b[4] & 0x7) << 8 | b[5];
+    float temp_c      = (temp_raw - 400) * 0.1f;    // range -40.0-60.0 C
+    int humidity      = b[6];
+    int battery_bars  = (b[7] & 0x40) >> 4 | (b[9] & 0xC0) >> 6;
+    // A battery bars value of 6 means the sensor is powered via USB (the Ecowitt WS View app shows 'DC')
+    int ext_power     = battery_bars == 6 ? 1 : 0;
+    //  Battery level is indicated with 5 bars. Convert to 0 (0 bars) to 1 (5 or 6 bars)
+    float battery_ok  = MIN(battery_bars * 0.2f, 1.0f);
+    int pm2_5_raw     = (b[7] & 0x3f) << 8 | b[8];
+    float pm2_5       = pm2_5_raw * 0.1f;
+    int pm10_raw      = (b[9] & 0x3f) << 8 | b[10];
+    float pm10        = pm10_raw * 0.1f;
+    int co2           = (b[11] << 8) | b[12];
+
+    /* clang-format off */
+    data_t *data = data_make(
+            "model",            "",             DATA_STRING, "Fineoffset-WH45",
+            "id",               "ID",           DATA_FORMAT, "%06x", DATA_INT, id,
+            "battery_ok",       "Battery Level",  DATA_FORMAT, "%.1f", DATA_DOUBLE, battery_ok,
+            "temperature_C",    "Temperature",  DATA_FORMAT, "%.01f C", DATA_DOUBLE, temp_c,
+            "humidity",         "Humidity",     DATA_FORMAT, "%u %%", DATA_INT, humidity,
+            "pm2_5_ug_m3",      "2.5um Fine Particulate Matter",  DATA_FORMAT, "%.1f ug/m3", DATA_DOUBLE, pm2_5,
+            "pm10_ug_m3",       "10um Coarse Particulate Matter",  DATA_FORMAT, "%.1f ug/m3", DATA_DOUBLE, pm10,
+            "co2_ppm",          "Carbon Dioxide", DATA_FORMAT, "%i ppm", DATA_INT, co2,
+            "ext_power",        "External Power", DATA_INT, ext_power,
+            "mic",              "Integrity",    DATA_STRING, "CRC",
+            NULL);
+    /* clang-format on */
+
+    decoder_output_data(decoder, data);
+    return 1;
+}
+
+static char *output_fields[] = {
+        "model",
+        "id",
+        "battery_ok",
+        "temperature_C",
+        "humidity",
+        "pm2_5_ug_m3",
+        "pm10_0_ug_m3",
+        "co2_ppm",
+        "ext_power",
+        "mic",
+        NULL,
+};
+
+r_device fineoffset_wh45 = {
+        .name        = "Fine Offset Electronics WH45 air quality sensor",
+        .modulation  = FSK_PULSE_PCM,
+        .short_width = 58,
+        .long_width  = 58,
+        .reset_limit = 2500,
+        .decode_fn   = &fineoffset_wh45_decode,
+        .fields      = output_fields,
+};