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