Added decoder for Dragino distance measuring sensors.

bmsapp/lora/decode_dragino.py

@@ -168,6 +168,27 @@ def decode_lwl01(data: bytes) -> Dict[str, Any]:
 
     return res
 
+def decode_ldds(data: bytes) -> Dict[str, Any]:
+    """Returns a dictionary of engineering values decoded from a Dragino distance measuring
+    sensor, including the LDDS20 and the LDDS75.
+    The payload 'data' is a byte array.
+    """
+
+    # holds the dictionary of results
+    res = {}
+
+    def int16(ix: int) -> int:
+        """Returns a 16-bit integer from the 2 bytes starting at index 'ix' in data byte array.
+        """
+        return (data[ix] << 8) | (data[ix + 1])
+
+    # Battery voltage
+    res['vdd'] = (int16(0) & 0x3FFF) / 1000
+
+    # Distance in millimeters
+    res['distance'] = int16(2)
+
+    return res
 
 def test_lht65():
     cases = (

bmsapp/lora/decoder.py

@@ -83,6 +83,8 @@ def decode(
             elif dev_id_lwr.startswith('boat-lt2'):
                 if integration_payload['port'] == 2:
                     fields = decode_dragino.decode_boat_lt2(payload)
+            elif dev_id_lwr.startswith('ldds'):
+                fields = decode_dragino.decode_ldds(payload)
 
             # some decoders will give a list of values back for one field.  If requested, convert 
             # these into multiple fields with an underscore index at end of field name.