Add support for Martec MPLCD ceiling fan remote

include/rtl_433_devices.h

@@ -282,6 +282,7 @@
     DECL(gridstream192) \
     DECL(gridstream384) \
     DECL(revolt_zx7717) \
+    DECL(martec_mplcd) \
 
     /* Add new decoders here. */
 

src/CMakeLists.txt

@@ -173,6 +173,7 @@ add_library(r_433 STATIC
     devices/m_bus.c
     devices/markisol.c
     devices/marlec_solar.c
+    devices/martec_mplcd.c
     devices/maverick_et73.c
     devices/maverick_et73x.c
     devices/maverick_xr30.c

src/devices/martec_mplcd.c

@@ -0,0 +1,130 @@
+/** @file
+    Decoder for Martec MPLCD ceiling fan remotes
+
+    Copyright (C) 2024 Don Ashdown
+
+    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.
+*/
+
+#include "decoder.h"
+#include <stdbool.h>
+
+/**
+Decoder for Martec MPLCD ceiling fan remotes
+
+Remote keeps knowledge of fan state and sends combined light and fan setting on each button press.
+
+Data layout:
+
+    22 bits
+    PPPP IIII DDDDDDD SS U CCCC
+
+- P: 4 bit fixed preamble 0x8
+- I: 4 bit channel ID - reflected and inverted
+- D: 7 bit dimmer - 0 is off, 1-41 is on with 1 being full brightness
+- S: 2 bit speed - 0: off, 1: high, 2: medium, 3: low
+- U: 1 bit unknown
+- C: 4 bit simple checksum
+
+Format string:
+
+    xxxx ID:4h LIGHT:7h FAN:2h x CRC:4b
+
+Process the data as 3 bytes skipping the first bit to simplify checksum calculation
+    P PPPIIIID DDDDDDSS UCCCC
+
+Checksum is simple sum over 4 nibbles starting from bit 2
+*/
+
+static int martec_mplcd_decode(r_device *decoder, bitbuffer_t *bitbuffer)
+{
+    char const *const speed_names[] = {
+            /* 0  */ "off",
+            /* 1  */ "high",
+            /* 2  */ "medium",
+            /* 3  */ "low",
+    };
+
+    int return_code = 0;
+    uint8_t previous_bytes[3] = {0,1,1}; // Initialize previous bytes to zero
+    bool is_first_code = true; // Flag to check if it's the first code
+
+    for (int row = 0; row < bitbuffer->num_rows; row++) {
+        int num_bits = bitbuffer->bits_per_row[row];
+
+        if (num_bits != 22) { // Max number of bits is 22
+            decoder_logf(decoder, 2, __func__, "Expected %d bits, got %d.", 22, num_bits);
+            continue;
+        }
+
+        uint8_t bytes[3]; // Max number of bytes is 3
+        bitbuffer_extract_bytes(bitbuffer, row, 1, bytes, 21); // Extract 21 bits starting from bit 1
+
+        // Skip repeated codes
+        if (!is_first_code && memcmp(previous_bytes, bytes, 3) == 0) {
+            continue;
+        }
+
+        // Calculate nibble sum and compare
+        int checksum = add_nibbles(bytes, 2);
+        checksum &= 0x0f;
+        int cks = (bytes[2] >> 3) & 0x0f;
+        if (checksum != cks) { // Sum is in byte 2
+            decoder_logf(decoder, 2, __func__, "Checksum failure: expected %x, got %x", cks, checksum);
+            continue;
+        }
+
+        int channel = (~bytes[0] >> 1) & 0x0f;
+        channel = reflect4(channel);
+        int dimmer = (bytes[0] & 0x01) << 6;
+        // Dimmer ranges from 1 to 41 with 1 being full brightness
+        dimmer += (bytes[1] >> 2) & 0x3f;
+        // Map dimmer to a continuous range from 0 to 41 with 0 being off and 41 being full brightness
+        if (dimmer > 0) {
+            dimmer = 42 - dimmer;
+        }
+        int speed = (bytes[1] & 0x03);
+
+        /* clang-format off */
+        data_t *data = data_make(
+                "model",            "",     DATA_STRING,    "Martec-MPLCD",
+                "id",               "",     DATA_INT,       channel,
+                "dimmer",           "",     DATA_INT,       dimmer,
+                "speed",            "",     DATA_STRING,    speed_names[speed],
+                "mic",              "",     DATA_STRING,    "CHECKSUM",
+                NULL);
+        /* clang-format on */
+
+        decoder_output_data(decoder, data);
+        return_code++;
+
+        // Update previous_bytes with the current code
+        memcpy(previous_bytes, bytes, 3);
+        is_first_code = false;
+    }
+
+    return return_code;
+}
+
+static char const *const output_fields[] = {
+        "model",
+        "id",
+        "dimmer",
+        "speed",
+        "mic",
+        NULL,
+};
+
+r_device const martec_mplcd = {
+        .name        = "Martec MPLCD Ceiling Fan Remote",
+        .modulation  = OOK_PULSE_PWM,
+        .short_width = 292,
+        .long_width  = 648,
+        .gap_limit   = 850,
+        .reset_limit = 12000,
+        .decode_fn   = &martec_mplcd_decode,
+        .fields      = output_fields,
+};