Add support for GM ABO1502T Car Remote

README.md

@@ -348,6 +348,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
     [260]  Microchip HCS361 KeeLoq Hopping Encoder based remotes (315.1M No Sync, 833 bit/s)
     [261]  Microchip HCS361 KeeLoq Hopping Encoder based remotes (315.1M No Sync, 1667 bit/s)
     [262]  6SC2 Car Remote (-f 315.1M -s 1024k)
+    [263]  GM ABO1502T Car Remote (-f 315.1M)
 
 * Disabled by default, use -R n or a conf file to enable
 

conf/rtl_433.example.conf

@@ -489,6 +489,7 @@ convert si
   protocol 260 # Microchip HCS361 KeeLoq Hopping Encoder based remotes (315.1M No Sync, 833 bit/s)
   protocol 261 # Microchip HCS361 KeeLoq Hopping Encoder based remotes (315.1M No Sync, 1667 bit/s)
   protocol 262 # 6SC2 Car Remote (-f 315.1M -s 1024k)
+  protocol 263 # GM ABO1502T Car Remote (-f 315.1M)
 
 ## Flex devices (command line option "-X")
 

include/rtl_433_devices.h

@@ -269,7 +269,8 @@
     DECL(hcs361_txwak_0_bsel_1) \
     DECL(hcs361_txwak_1_bsel_0) \
     DECL(hcs361_txwak_1_bsel_1) \
-    DECL(six_sc_two_car_remote)
+    DECL(six_sc_two_car_remote) \
+    DECL(gm_car_remote)
 
     /* Add new decoders here. */
 

src/CMakeLists.txt

@@ -131,6 +131,7 @@ add_library(r_433 STATIC
     devices/generic_remote.c
     devices/generic_temperature_sensor.c
     devices/geo_minim.c
+    devices/gm_car_remote.c
     devices/govee.c
     devices/gt_tmbbq05.c
     devices/gt_wt_02.c

src/devices/gm_car_remote.c

@@ -0,0 +1,134 @@
+/** @file
+    GM - Car Remote.
+
+    Copyright (C) 2023 Ethan Halsall
+
+    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.
+*/
+/** @fn int gm_car_remote_decode(r_device *decoder, bitbuffer_t *bitbuffer)
+General Motors - Car Remote (315 MHz)
+
+Manufacturer:
+- General Motors
+
+Supported Models:
+- ABO1502T
+
+Data structure:
+
+The transmitter uses a rolling code message with an unencrypted sequence number.
+
+Button operation:
+This transmitter has 2 to 4 buttons which can be pressed once to transmit a single message
+
+Data layout:
+
+PP xxxx cccc IIIIIIII SSSSSS EEEEEE CC
+
+- P: 8 bit unknown, possibly part of the ID
+- c: 4 bit checksum of button code
+- b: 4 bit button code
+- I: 32 bit ID
+- S: 24 bit sequence
+- E: 24 bit encrypted
+- C: 8 bit checksum of entire payload
+
+Format string:
+
+UNKNOWN: bbbbbbbb BUTTON_CHECKSUM: bbbb BUTTON: bbbb ID: hhhhhhhh SEQUENCE: hhhhhh ENCRYPTED: hhhhhh CHECKSUM: hh
+
+*/
+
+#include "decoder.h"
+
+static int gm_car_remote_decode(r_device *decoder, bitbuffer_t *bitbuffer)
+{
+    if (bitbuffer->bits_per_row[0] < 113 || bitbuffer->num_rows > 1) {
+        return DECODE_ABORT_LENGTH;
+    }
+
+    // a long wake up payload is sent that may be truncated, so start from the end of the payload.
+    int offset = bitbuffer->bits_per_row[0] - 113;
+
+    uint8_t bytes[14];
+    bitbuffer_extract_bytes(bitbuffer, 0, offset, bytes, 112);
+
+    // check one byte from the wake up signal
+    if (bytes[0] != 0xff) {
+        return DECODE_FAIL_SANITY;
+    }
+
+    // validate mic
+    int button_checksum = add_nibbles(bytes + 2, 1);
+    if (button_checksum == 0 || (button_checksum & 0xf) != 0) {
+        return DECODE_FAIL_MIC;
+    }
+
+    int full_checksum = add_bytes(bytes + 1, 13);
+    if (full_checksum == 0 || (full_checksum & 0xff) != 0) {
+        return DECODE_FAIL_MIC;
+    }
+
+    // parse payload
+    int button         = bytes[2] & 0x7;
+    uint32_t id        = (bytes[3] << 24) | (bytes[4] << 16) | (bytes[5] << 8) | bytes[6];
+    int sequence       = (bytes[7] << 16) | (bytes[8] << 8) | bytes[9];
+    uint32_t encrypted = (bytes[10] << 16) | (bytes[11] << 8) | bytes[12];
+
+    char id_str[11];
+    snprintf(id_str, sizeof(id_str), "%02X%08X", bytes[1], id);
+
+    char encrypted_str[7];
+    snprintf(encrypted_str, sizeof(encrypted_str), "%06X", encrypted);
+
+    char const *button_str;
+
+    /* clang-format off */
+    switch (button) {
+        case 0x1: button_str = "Unlock"; break;
+        case 0x2: button_str = "Lock"; break;
+        case 0x3: button_str = "Trunk"; break;
+        case 0x4: button_str = "Panic"; break;
+        default: button_str = "?"; break;
+    }
+    /* clang-format on */
+
+    /* clang-format off */
+    data_t *data = data_make(
+            "model",            "model",       DATA_STRING, "GM-ABO1502T",
+            "id",               "ID",          DATA_STRING, id_str,      
+            "encrypted",        "",            DATA_STRING, encrypted_str,
+            "button_code",      "Button Code", DATA_INT,    button,
+            "button_str",       "Button",      DATA_STRING, button_str,
+            "sequence",         "Sequence",    DATA_INT,    sequence,
+            "mic",              "Integrity",   DATA_STRING, "CHECKSUM",
+            NULL);
+    /* clang-format on */
+
+    decoder_output_data(decoder, data);
+    return 1;
+}
+
+static char const *const output_fields[] = {
+        "model",
+        "id",
+        "encrypted",
+        "button_code",
+        "button_str",
+        "sequence",
+        "mic",
+        NULL,
+};
+
+r_device const gm_car_remote = {
+        .name        = "GM ABO1502T Car Remote (-f 315.1M)",
+        .modulation  = OOK_PULSE_PPM,
+        .short_width = 300,
+        .long_width  = 500,
+        .reset_limit = 20000,
+        .decode_fn   = &gm_car_remote_decode,
+        .fields      = output_fields,
+};