Add Amazon Basics Meat Thermometer decoder

Author: Benjamin Larsson

README.md

@@ -259,6 +259,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
     [178]  Security+ (Keyfob)
     [179]  Cavius smoke, heat and water detector
     [180]  Jansite TPMS Model Solar
+    [181]  Amazon Basics Meat Thermometer
 
 * Disabled by default, use -R n or -G
 

conf/rtl_433.example.conf

@@ -362,6 +362,7 @@ stop_after_successful_events false
   protocol 178 # Security+ (Keyfob)
   protocol 179 # Cavius smoke, heat and water detector
   protocol 180 # Jansite TPMS Model Solar
+  protocol 181 # Amazon Basics Meat Thermometer
 
 ## Flex devices (command line option "-X")
 

include/rtl_433_devices.h

@@ -188,6 +188,7 @@
     DECL(secplus_v1) \
     DECL(cavius) \
     DECL(tpms_jansite_solar) \
+    DECL(abmt) \
     /* Add new decoders here. */
 
 #define DECL(name) extern r_device name;

src/CMakeLists.txt

@@ -35,6 +35,7 @@ add_library(r_433 STATIC
     term_ctl.c
     util.c
     write_sigrok.c
+    devices/abmt.c
     devices/acurite.c
     devices/akhan_100F14.c
     devices/alecto.c

src/Makefile.am

@@ -34,6 +34,7 @@ rtl_433_SOURCES      = abuf.c \
                        term_ctl.c \
                        util.c \
                        write_sigrok.c \
+                       devices/abmt.c \
                        devices/acurite.c \
                        devices/akhan_100F14.c \
                        devices/alecto.c \

src/devices/abmt.c

@@ -0,0 +1,101 @@
+/** @file
+    Amazon Basics Meat Thermometer
+
+    Copyright (C) 2021 Benjamin Larsson
+
+    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.
+*/
+/**
+Amazon Basics Meat Thermometer
+
+Manchester encoded PCM signal.
+
+[00] {48} e4 00 a3 01 40 ff
+
+II 00 UU TT T0 FF
+
+I - power on random id
+0 - zeros
+U - Unknown
+T - bcd coded temperature
+F - ones
+
+
+*/
+#include "decoder.h"
+
+#define SYNC_PATTERN_START_OFF 72
+
+// Convert two BCD encoded nibbles to an integer
+static unsigned bcd2int(uint8_t bcd)
+{
+    return 10*(bcd>>4) + (bcd & 0xF);
+}
+
+static int abmt_callback(r_device *decoder, bitbuffer_t *bitbuffer)
+{
+    int row;
+    float temp_c;
+    bitbuffer_t packet_bits = {0};
+    unsigned int id;
+    data_t *data;
+    unsigned bitpos = 0;
+    uint8_t *b;
+    int16_t temp;
+    uint8_t const sync_pattern[3] = {0x55, 0xAA, 0xAA};
+
+    // Find repeats
+    row = bitbuffer_find_repeated_row(bitbuffer, 4, 90);
+    if (row < 0)
+        return DECODE_ABORT_EARLY;
+
+    if (bitbuffer->bits_per_row[row] > 120)
+        return DECODE_ABORT_LENGTH;
+
+    // search for 24 bit sync pattern
+    bitpos = bitbuffer_search(bitbuffer, row, bitpos, sync_pattern, 24);
+    // if sync is not found or sync is found with to little bits available, abort
+    if ((bitpos == bitbuffer->bits_per_row[row]) || (bitpos < SYNC_PATTERN_START_OFF))
+        return DECODE_FAIL_SANITY;
+
+    // sync bitstream
+    bitbuffer_manchester_decode(bitbuffer, row, bitpos-SYNC_PATTERN_START_OFF, &packet_bits, 48);
+    bitbuffer_invert(&packet_bits);
+    
+    b = packet_bits.bb[0];
+    id = b[0];
+    temp = bcd2int(b[3])*10 + bcd2int(b[4]>>4);
+    temp_c = (float)temp;
+
+    /* clang-format off */
+     data = data_make(
+             "model",            "",             DATA_STRING, "AmazonBasicsMeatThermometer",
+             "id",            "Id",          DATA_INT,    id,
+             "temperature_C", "Temperature", DATA_FORMAT, "%.01f C", DATA_DOUBLE, temp_c,
+             NULL);
+    /* clang-format on */
+    decoder_output_data(decoder, data);
+    return 1;
+}
+
+static char *output_fields[] = {
+        "model",
+        "id",
+        "temperature_C",
+        NULL,
+};
+
+r_device abmt = {
+        .name        = "Amazon Basics Meat Thermometer",
+        .modulation  = OOK_PULSE_PCM_RZ,
+        .short_width = 550,
+        .long_width  = 550,
+        .gap_limit   = 2000,
+        .reset_limit = 5000,
+        .decode_fn   = &abmt_callback,
+        .disabled    = 0,
+        .fields      = output_fields,
+};

vs15/rtl_433.vcxproj

@@ -163,6 +163,7 @@ COPY ..\..\libusb\MS64\dll\libusb*.dll $(TargetDir)</Command>
     <ClCompile Include="..\src\term_ctl.c" />
     <ClCompile Include="..\src\util.c" />
     <ClCompile Include="..\src\write_sigrok.c" />
+    <ClCompile Include="..\src\devices\abmt.c" />
     <ClCompile Include="..\src\devices\acurite.c" />
     <ClCompile Include="..\src\devices\akhan_100F14.c" />
     <ClCompile Include="..\src\devices\alecto.c" />

vs15/rtl_433.vcxproj.filters

@@ -226,6 +226,9 @@
     <ClCompile Include="..\src\getopt\getopt.c">
       <Filter>Source Files\getopt</Filter>
     </ClCompile>
+    <ClCompile Include="..\src\devices\abmt.c">
+      <Filter>Source Files\devices</Filter>
+    </ClCompile>
     <ClCompile Include="..\src\devices\acurite.c">
       <Filter>Source Files\devices</Filter>
     </ClCompile>