Adds checksum and battery_ok for WEC-2103.

src/devices/wec2103.c

@@ -14,58 +14,70 @@
 /**
 WEC-2103 temperature/humidity sensor.
 
+Circuit board model numbers: TX07Y-THC V1, TX07K-THC V4
+
 Similar to prologue, kedsum, esperanza_ews, s3318p
 Only available information for this device: https://fcc.report/FCC-ID/WEC-2103
 
 Data:
 
     Byte:      0        1        2        3        4        5
     Nibble:    1   2    3   4    5   6    7   8    9   10   11
-    Type:      IIIIIIII XXXXFFFF TTTTTTTT TTTTHHHH HHHHCCCC ????
+    Type:      IIIIIIII XXXXFFFF TTTTTTTT TTTTHHHH HHHHCCCC SS
 
 - I: random device ID, changes on powercycle
-- X: Checksum?
-- F: Flags
+- X: Checksum: mangled CRC-4, poly 3, init 0.
+- F: Flags: tx-button pressed|batt-low|?|?
 - T: Temperature
 - H: Humidity
-- Flags: tx-button pressed|?|?|?
+- S: Stop bit(s): 0b10
 
 Example datagram:
 
-     f2 90              6b5         96       1       8
-    |ID|Checksum?+Flags|Temperature|Humidity|Channel|unknown
+     f2 90             6b5         96       1       8
+    |ID|Checksum+Flags|Temperature|Humidity|Channel|Stop bits
 
 - Temperature in Fahrenheit*100+900->hex
 - Example: 82.4F->824->1724->0x6bc
 */
 
 static int wec2103_decode(r_device *decoder, bitbuffer_t *bitbuffer)
 {
-    if (bitbuffer->num_rows != 6  || bitbuffer->bits_per_row[2] != 42)
+    if (bitbuffer->num_rows != 6 || bitbuffer->bits_per_row[2] != 42) {
         return DECODE_ABORT_LENGTH;
-
-    uint8_t b[6];
-    bitbuffer_extract_bytes(bitbuffer, 3, 0, b, 42);
-
-    int temp_raw  = (b[2] << 4) | ((b[3] & 0xf0) >> 4);
-    int device_id = b[0];
-    int channel   = b[4] & 0x0f;
-    int flags     = b[1] & 0xf;
-    float temp_f  = (temp_raw - 900) * 0.1f;
-    int humidity  = ((b[3] & 0x0f) * 10) + ((b[4] & 0xf0) >> 4);
-    int button    = (b[1] & 0x08) >> 3;
+    }
+
+    uint8_t b[5];
+    bitbuffer_extract_bytes(bitbuffer, 3, 0, b, 40);
+
+    int crc_received = b[1] >> 4;
+    b[1] = (b[1] & 0x0F) | ((b[4] & 0x0f) << 4);
+    int crc_calculated = crc4(b, sizeof(b) - 1, 3, 0) ^ (b[4] >> 4);
+    if (crc_calculated != crc_received) {
+        decoder_logf(decoder, 0, __func__, "CRC check failed (0x%X != 0x%X)", crc_calculated, crc_received);
+        return DECODE_FAIL_MIC;
+    }
+
+    int temp_raw    = (b[2] << 4) | ((b[3] & 0xf0) >> 4);
+    int device_id   = b[0];
+    int channel     = b[4] & 0x0f;
+    int flags       = b[1] & 0xf;
+    float temp_f    = (temp_raw - 900) * 0.1f;
+    int humidity    = ((b[3] & 0x0f) * 10) + ((b[4] & 0xf0) >> 4);
+    int button      = (b[1] & 0x08) >> 3;
+    int battery_low = (b[1] & 0x04) >> 3;
 
     /* clang-format off */
     data_t *data = data_make(
             "model",            "",             DATA_STRING, "WEC-2103",
             "id",               "ID",           DATA_INT,    device_id,
             "channel",          "Channel",      DATA_INT,    channel,
-            //"battery_ok",       "Battery",      DATA_INT,    !battery_low,
-            "flags",            "Flags",       DATA_INT,    flags,
+            "battery_ok",       "Battery",      DATA_INT,    !battery_low,
+            "button",           "Button",       DATA_INT,    button,
             "temperature_F",    "Temperature",  DATA_FORMAT, "%.02f F", DATA_DOUBLE, temp_f,
             "humidity",         "Humidity",     DATA_FORMAT, "%u %%", DATA_INT, humidity,
-            "button",           "Button",       DATA_INT,    button,
-            //"mic",              "Integrity",    DATA_STRING, "CRC",
+            "flags",            "Flags",        DATA_INT,    flags,
+            "mic",              "Integrity",    DATA_STRING, "CRC",
             NULL);
     /* clang-format on */
 
@@ -77,9 +89,12 @@ static char const *const output_fields[] = {
         "model",
         "id",
         "channel",
-        "flags",
+        "battery_ok",
+        "button",
         "temperature_F",
         "humidity",
+        "flags",
+        "mic",
         NULL,
 };
 
@@ -91,6 +106,5 @@ r_device const wec2103 = {
         .gap_limit      = 4400,
         .reset_limit    = 9400,
         .decode_fn      = &wec2103_decode,
-        .disabled       = 1, // no checksum
         .fields         = output_fields,
 };