- refactored

- added claude.md

ubx/ubx.py

@@ -1,6 +1,8 @@
 import struct
 
-UBX_SYNC_WORD = b'\xb5\x62'
+from ubx.msg_types import *
+
+UBX_SYNC_WORD     = struct.pack('BB', UBX_SYNC1, UBX_SYNC2)
 
 def checksum(data: bytes) -> bytes:
 	ck_a = 0
@@ -11,14 +13,13 @@ def checksum(data: bytes) -> bytes:
 
 	return struct.pack("BB", ck_a, ck_b)
 
-def frame_create(_class: int, _id: int, _data: bytes) -> bytes:
-	_sync = b'\xb5\x62'
+def frame_create(_class: int, _id: int, _data: bytes = b'') -> bytes:
 	_hdr = struct.pack('B', _class)
 	_hdr += struct.pack('B', _id)
 	_hdr += struct.pack('<H', len(_data))
 	_check = checksum(_hdr + _data)
 
-	return _sync + _hdr + _data + _check
+	return UBX_SYNC_WORD + _hdr + _data + _check
 
 class Hdr:
 	def __init__(self, _class: int, _id: int, _length: int):