Add support for Carchet TPMS (#2677)

Co-authored-by: Karen Suhm <kesuhm@users.noreply.github.com>

README.md

@@ -38,7 +38,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
 ```
 
   A "rtl_433.conf" file is searched in "./", XDG_CONFIG_HOME e.g. "$HOME/.config/rtl_433/",
-  "/usr/local/etc/rtl_433/", "/etc/rtl_433/", then command line args will be parsed in order.
+  SYSCONFDIR e.g. "/usr/local/etc/rtl_433/", then command line args will be parsed in order.
 		= General options =
   [-V] Output the version string and exit
   [-v] Increase verbosity (can be used multiple times).
@@ -314,7 +314,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
     [226]  Kia TPMS (-s 1000k)
     [227]  SRSmith Pool Light Remote Control SRS-2C-TX (-f 915M)
     [228]  Neptune R900 flow meters
-    [229]* WEC-2103 temperature/humidity sensor
+    [229]  WEC-2103 temperature/humidity sensor
     [230]  Vauno EN8822C
     [231]  Govee Water Leak Detector H5054
     [232]  TFA Dostmann 14.1504.V2 Radio-controlled grill and meat thermometer
@@ -326,7 +326,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
     [238]  Wireless M-Bus, Mode T, 32.768kbps (-f 868.3M -s 1000k)
     [239]  Revolt NC-5642 Energy Meter
     [240]  LaCrosse TX31U-IT, The Weather Channel WS-1910TWC-IT
-    [241]  EezTire E618 (TPMS10ATC)
+    [241]  EezTire E618, Carchet TPMS
     [242]* Baldr / RainPoint rain gauge.
     [243]  Celsia CZC1 Thermostat
     [244]  Fine Offset Electronics WS90 weather station

conf/rtl_433.example.conf

@@ -455,7 +455,7 @@ convert si
   protocol 226 # Kia TPMS (-s 1000k)
   protocol 227 # SRSmith Pool Light Remote Control SRS-2C-TX (-f 915M)
   protocol 228 # Neptune R900 flow meters
-# protocol 229 # WEC-2103 temperature/humidity sensor
+  protocol 229 # WEC-2103 temperature/humidity sensor
   protocol 230 # Vauno EN8822C
   protocol 231 # Govee Water Leak Detector H5054
   protocol 232 # TFA Dostmann 14.1504.V2 Radio-controlled grill and meat thermometer
@@ -467,7 +467,7 @@ convert si
   protocol 238 # Wireless M-Bus, Mode T, 32.768kbps (-f 868.3M -s 1000k)
   protocol 239 # Revolt NC-5642 Energy Meter
   protocol 240 # LaCrosse TX31U-IT, The Weather Channel WS-1910TWC-IT
-  protocol 241 # EezTire E618 (TPMS10ATC)
+  protocol 241 # EezTire E618, Carchet TPMS
 # protocol 242 # Baldr / RainPoint rain gauge.
   protocol 243 # Celsia CZC1 Thermostat
   protocol 244 # Fine Offset Electronics WS90 weather station

man/man1/rtl_433.1

@@ -40,7 +40,7 @@ Detailed information on some options follows.
 
 
   A "rtl_433.conf" file is searched in "./", XDG_CONFIG_HOME e.g. "$HOME/.config/rtl_433/",
-  "/usr/local/etc/rtl_433/", "/etc/rtl_433/", then command line args will be parsed in order.
+  SYSCONFDIR e.g. "/usr/local/etc/rtl_433/", then command line args will be parsed in order.
 .SS "General options"
 .TP
 [ \fB\-V\fI\fP ]

src/devices/tpms_eezrv.c

@@ -1,7 +1,7 @@
 /** @file
-    EezTire E618 TPMS.
+    EezTire E618 TPMS and Carchet TPMS (same protocol).
 
-    Copyright (C) 2023 Bruno OCTAU (ProfBoc75) and Gliebig
+    Copyright (C) 2023 Bruno OCTAU (ProfBoc75), Gliebig, and Karen Suhm
 
     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
@@ -12,22 +12,48 @@
 #include "decoder.h"
 
 /**
-EezTire E618 TPMS.
+EezTire E618 TPMS and Carchet TPMS (same protocol).
 
 Eez RV supported TPMS sensor model E618 : https://eezrvproducts.com/shop/ols/products/tpms-system-e518-anti-theft-replacement-sensor-1-ea
+Carchet TPMS: http://carchet.easyofficial.com/carchet-rv-trailer-car-solar-tpms-tire-pressure-monitoring-system-6-sensor-lcd-display-p6.html
 
-S.a issue #2384, #2657
+The device uses OOK (ASK) encoding.
+The device sends a transmission every 1 second when quick deflation is detected, every 13 - 23 sec when quick inflation is detected, and every 4 min 40 s under steady state pressure.
+A transmission starts with a preamble of 0x0000 and the packet is sent twice.
 
-Data layout:
+S.a issue #2384, #2657, #2063, #2677
+
+Data collection parameters on URH software were as follows:
+    Sensor frequency: 433.92 MHz
+    Sample rate: 2.0 MSps
+    Bandwidth: 2.0 Hz
+    Gain: 125
+
+    Modulation is ASK (OOK). Packets in URH arrive in the following format:
+
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa [Pause: 897679 samples]
+    aaaaaaaa5956a5a5a6555aaa65959999a5aaaaaa [Pause: 6030 samples]
+    aaaaaaaa5956a5a5a6555aaa65959999a5aaaaaa [Pause: 11176528 samples]
+
+    Decoding is Manchester I.  After decoding, the packets look like this:
+
+    00000000000000000000000000000000000000
+    0000de332fc0b7553000
+    0000de332fc0b7553000
+
+ Using rtl_433 software, packets were detected using the following command line entry:
+ rtl_433 -X "n=Carchet,m=OOK_MC_ZEROBIT,s=50,l=50,r=1000,invert" -s 1M
+
+ Data layout:
 
     PRE CC IIIIII PP TT FF FF
 
 - PRE : FFFF
-- C : 8 bit CheckSum
+- C : 8 bit CheckSum, modulo 256 with overflow flag
-- I: 24 bit ID
+- I: 24 bit little-endian ID
 - P: 8 bit pressure  P * 2.5 = Pressure kPa
 - T: 8 bit temperature   T - 50 = Temperature C
-- F: 16  bit battery (not verified), deflation pressure (for sure), pressure MSB
+- F: 16 bit status flags: 0x8000 = low battery, 0x1000 = quick deflation, 0x3000 = quick inflation, 0x0000 = static/steady state
 
 Raw Data example :
 
@@ -83,12 +109,16 @@ static int tpms_eezrv_decode(r_device *decoder, bitbuffer_t *bitbuffer)
     int temperature_C      = b[4] - 50;
     int flags1             = b[5];
     int flags2             = b[6];
-    int fast_leak_detected = (flags1 & 0x10);
+    int fast_leak_detected = (flags1 & 0x10);      // fast leak - reports every second
-    int fast_leak_resolved = (flags1 & 0x20);
+    int infl_detected      = (flags1 & 0x20) >> 5; // inflating - reports every 15 - 20 sec
 
-    int fast_leak = fast_leak_detected && !fast_leak_resolved;
+    int fast_leak      = fast_leak_detected && !infl_detected;
     float pressure_kPa = (((flags2 & 0x01) << 8) + b[3]) * 2.5;
 
+    // Low batt = 0x8000;
+    int low_batt = flags1 >> 7; // Low batt flag is MSB (activated at V < 3.15 V)(Device fails at V < 3.10 V)
+    // Mystery flag at (flags2 & 0x20) showed up during low batt testing
+
     char id_str[7];
     snprintf(id_str, sizeof(id_str), "%02x%02x%02x", b[0], b[1], b[2]);
 
@@ -100,10 +130,12 @@ static int tpms_eezrv_decode(r_device *decoder, bitbuffer_t *bitbuffer)
             "model",            "",             DATA_STRING, "EezTire-E618",
             "type",             "",             DATA_STRING, "TPMS",
             "id",               "",             DATA_STRING, id_str,
+            "battery_ok",       "Battery_OK",   DATA_INT,    !low_batt,
             "pressure_kPa",     "Pressure",     DATA_FORMAT, "%.0f kPa", DATA_DOUBLE, (double)pressure_kPa,
             "temperature_C",    "Temperature",  DATA_FORMAT, "%.1f C", DATA_DOUBLE, (double)temperature_C,
-            "fast_leak",        "Fast Leak",    DATA_INT,    fast_leak,
             "flags",            "Flags",        DATA_STRING, flags_str,
+            "fast_leak",        "Fast Leak",    DATA_INT,    fast_leak,
+            "inflate",          "Inflate",      DATA_INT,    infl_detected,
             "mic",              "Integrity",    DATA_STRING, "CHECKSUM",
             NULL);
     /* clang-format on */
@@ -116,16 +148,18 @@ static char const *const output_fields[] = {
         "model",
         "type",
         "id",
-        "temperature_C",
+        "battery_ok",
         "pressure_kPa",
-        "fast_leak",
+        "temperature_C",
         "flags",
+        "fast_leak",
+        "inflate",
         "mic",
         NULL,
 };
 
 r_device const tpms_eezrv = {
-        .name        = "EezTire E618",
+        .name        = "EezTire E618, Carchet TPMS",
         .modulation  = OOK_PULSE_MANCHESTER_ZEROBIT,
         .short_width = 50,
         .long_width  = 50,