Add support for Porsche Boxter/Cayman TPMS

README.md

@@ -286,6 +286,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
     [200]* Auriol 4-LD5661 temperature/rain sensor
     [201]  Unbranded SolarTPMS for trucks
     [202]  Funkbus / Instafunk (Berker, Jira, Jung)
+    [203]  Porsche Boxster/Cayman TPMS
 
 * Disabled by default, use -R n or -G
 
@@ -323,6 +324,7 @@ Common keys are:
 	reset=<reset> (or: r=<reset>)
 	gap=<gap> (or: g=<gap>)
 	tolerance=<tolerance> (or: t=<tolerance>)
+	priority=<n> : run decoder only as fallback
 where:
 <name> can be any descriptive name tag you need in the output
 <modulation> is one of:

conf/rtl_433.example.conf

@@ -423,6 +423,7 @@ stop_after_successful_events false
 # protocol 200 # Auriol 4-LD5661 temperature/rain sensor
   protocol 201 # Unbranded SolarTPMS for trucks
   protocol 202 # Funkbus / Instafunk (Berker, Jira, Jung)
+  protocol 203 # Porsche Boxster/Cayman TPMS
 
 ## Flex devices (command line option "-X")
 

include/rtl_433_devices.h

@@ -210,6 +210,7 @@
     DECL(auriol_4ld5661) \
     DECL(tpms_truck) \
     DECL(funkbus_remote) \
+    DECL(tpms_porsche) \
 
     /* Add new decoders here. */
 

man/man1/rtl_433.1

@@ -225,6 +225,9 @@ gap=<gap> (or: g=<gap>)
 .RS
 tolerance=<tolerance> (or: t=<tolerance>)
 .RE
+.RS
+priority=<n> : run decoder only as fallback
+.RE
 where:
 <name> can be any descriptive name tag you need in the output
 <modulation> is one of:

src/CMakeLists.txt

@@ -196,6 +196,7 @@ add_library(r_433 STATIC
     devices/tpms_jansite.c
     devices/tpms_jansite_solar.c
     devices/tpms_pmv107j.c
+    devices/tpms_porsche.c
     devices/tpms_renault.c
     devices/tpms_toyota.c
     devices/tpms_truck.c

src/devices/tpms_porsche.c

@@ -0,0 +1,121 @@
+/**  @file
+    Porsche Boxster/Cayman TPMS.
+
+    Copyright (C) 2021 Christian W. Zuckschwerdt <zany@triq.net>
+
+    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.
+*/
+
+/**
+Porsche Boxster/Cayman TPMS.
+Seen on Porsche second generation (Typ 987) Boxster/Cayman.
+
+Full preamble is {30}ccccccca (33333332).
+The data is Differential Manchester Coded (DMC).
+
+Example data:
+
+    {193}333333354ab32d334b2d4ab2cab54cb34cb2aab4cd552ccd8
+    {193}333333354ab32d334b2d4ab2caaab34cb34d554aacd2b2cd8
+
+    23d7 ad23 623b bb02 f05f
+    23d7 ad23 603b bb02 1d37
+
+Data layout (nibbles):
+
+    II II II II PP TT SS SS CC
+
+- I: 32 bit ID
+- P: 8 bit Pressure (scale?)
+- T: 8 bit Temperature (deg. C offset by 40)
+- S: Status?
+- C: 16 bit Checksum, CRC-16 poly 0x1021 init 0xffff
+*/
+
+#include "decoder.h"
+
+static int tpms_porsche_decode(r_device *decoder, bitbuffer_t *bitbuffer, unsigned row, unsigned bitpos)
+{
+    bitbuffer_t packet_bits = {0};
+    bitbuffer_differential_manchester_decode(bitbuffer, row, bitpos, &packet_bits, 80);
+
+    // make sure we decoded the expected number of bits
+    if (packet_bits.bits_per_row[0] < 80) {
+        // fprintf(stderr, "bitpos=%u start_pos=%u = %u\n", bitpos, start_pos, (start_pos - bitpos));
+        return 0; // DECODE_FAIL_SANITY;
+    }
+
+    uint8_t *b = packet_bits.bb[0];
+
+    // Checksum is CRC-16 poly 0x1021 init 0xffff over 8 bytes
+    int checksum = crc16(b, 10, 0x1021, 0xffff);
+    if (checksum != 0) {
+        return 0; //DECODE_FAIL_MIC;
+    }
+
+    int id          = (unsigned)b[0] << 24 | b[1] << 16 | b[2] << 8 | b[3];
+    int pressure    = b[4];
+    int temperature = b[5];
+    int flags       = b[6] << 8 | b[7];
+
+    char id_str[4 * 2 + 1];
+    sprintf(id_str, "%08x", id);
+
+    /* clang-format off */
+    data_t *data = data_make(
+            "model",            "",             DATA_STRING, "Porsche",
+            "type",             "",             DATA_STRING, "TPMS",
+            "id",               "",             DATA_STRING, id_str,
+            "pressure",         "Pressure",     DATA_INT, pressure, // need to find the scaling
+            "temperature_C",    "Temperature",  DATA_FORMAT, "%.0f C", DATA_DOUBLE, (float)temperature - 40.0,
+            "flags",            "",             DATA_FORMAT, "%04x", DATA_INT, flags,
+            "mic",              "Integrity",    DATA_STRING, "CRC",
+            NULL);
+    /* clang-format on */
+
+    decoder_output_data(decoder, data);
+    return 1;
+}
+
+/** @sa tpms_porsche_decode() */
+static int tpms_porsche_callback(r_device *decoder, bitbuffer_t *bitbuffer)
+{
+    // Full preamble is {30}ccccccca (33333332).
+    uint8_t const preamble_pattern[] = {0x33, 0x33, 0x20}; // 20 bit
+
+    int events = 0;
+
+    // Find a preamble with enough bits after it that it could be a complete packet
+    unsigned bitpos = 0;
+    while ((bitpos = bitbuffer_search(bitbuffer, 0, bitpos, preamble_pattern, 20)) + 100 <=
+            bitbuffer->bits_per_row[0]) {
+        events += tpms_porsche_decode(decoder, bitbuffer, 0, bitpos + 20);
+        bitpos += 2;
+    }
+
+    return events;
+}
+
+static char *output_fields[] = {
+        "model",
+        "type",
+        "id",
+        "pressure",
+        "temperature_C",
+        "flags",
+        "mic",
+        NULL,
+};
+
+r_device tpms_porsche = {
+        .name        = "Porsche Boxster/Cayman TPMS",
+        .modulation  = FSK_PULSE_PCM,
+        .short_width = 52,  // 12-13 samples @250k
+        .long_width  = 52,  // FSK
+        .reset_limit = 150, // Maximum gap size before End Of Message [us].
+        .decode_fn   = &tpms_porsche_callback,
+        .fields      = output_fields,
+};

vs15/rtl_433.vcxproj

@@ -325,6 +325,7 @@ COPY ..\..\libusb\MS64\dll\libusb*.dll $(TargetDir)</Command>
     <ClCompile Include="..\src\devices\tpms_jansite.c" />
     <ClCompile Include="..\src\devices\tpms_jansite_solar.c" />
     <ClCompile Include="..\src\devices\tpms_pmv107j.c" />
+    <ClCompile Include="..\src\devices\tpms_porsche.c" />
     <ClCompile Include="..\src\devices\tpms_renault.c" />
     <ClCompile Include="..\src\devices\tpms_toyota.c" />
     <ClCompile Include="..\src\devices\tpms_truck.c" />

vs15/rtl_433.vcxproj.filters

@@ -712,6 +712,9 @@
     <ClCompile Include="..\src\devices\tpms_pmv107j.c">
       <Filter>Source Files\devices</Filter>
     </ClCompile>
+    <ClCompile Include="..\src\devices\tpms_porsche.c">
+      <Filter>Source Files\devices</Filter>
+    </ClCompile>
     <ClCompile Include="..\src\devices\tpms_renault.c">
       <Filter>Source Files\devices</Filter>
     </ClCompile>