feat: add packets

packets.py

@@ -0,0 +1,96 @@
+class Packet:
+    """Represents an 8-byte I2C packet."""
+    LENGTH = 8
+
+    def __init__(self, data=None):
+        if data is None:
+            data = [0] * self.LENGTH
+        if len(data) != self.LENGTH:
+            raise ValueError(f"Packet must be {self.LENGTH} bytes")
+        self.bytes = data
+
+    @classmethod
+    def from_bytes(cls, byte_list):
+        """Create Packet from list of bytes."""
+        return cls(byte_list[:cls.LENGTH])
+
+    def __getitem__(self, idx):
+        return self.bytes[idx]
+
+    def __setitem__(self, idx, value):
+        self.bytes[idx] = value
+
+    def __repr__(self):
+        fields = [f"Byte {i}: 0x{b:02X}" for i, b in enumerate(self.bytes)]
+        return "\n".join(fields)
+
+    def as_list(self):
+        return self.bytes
+
+    def is_valid(self):
+        """Verify checksum (XOR of bytes 0-6 equals byte 7)."""
+        cs = 0
+        for b in self.bytes[:-1]:
+            cs ^= b
+        return cs == self.bytes[-1]
+
+def create_motor_state_packet(fl=None, fr=None, bl=None, br=None):
+    """
+    Create an 8-byte packet to set motor states for I2C transfer.
+    Packet format:
+    [0x01, 0x00, FL, FR, BL, BR, 0x00, checksum]
+    - 0x01: Command for Motor State Packet
+    - 0x00: Target/channel (set as needed)
+    - FL, FR, BL, BR: Motor states (0x00 = off, 0x01 = forward, 0x02 = backward)
+    - checksum: XOR of bytes 0-6
+    """
+    def getByteForState(state):
+        if state:
+            return 0x01
+        elif not state:
+            return 0x02
+        else: 
+            return 0x00
+
+    packet = [0x01, 0x00, getByteForState(fl), getByteForState(fr), getByteForState(bl), getByteForState(br), 0x00]
+    checksum = 0
+    for b in packet:
+        checksum ^= b
+    packet.append(checksum)
+    return Packet.from_bytes(bytes(packet))
+
+def create_tail_wagging_packet(wagging=False):
+    """
+    Create an 8-byte packet to set wagging for I2C transfer.
+    Packet format:
+    [0x02, 0x00, Wagging, 0x00, 0x00, 0x00, 0x00, checksum]
+    - 0x02: Command for Wagging Packet
+    - 0x00: Target/channel (set as needed)
+    - Wagging: 0x00 = false, 0x01 = true
+    - checksum: XOR of bytes 0-6
+    """
+    packet = [0x02, 0x00, 0x01 if wagging else 0x00, 0x00, 0x00, 0x00, 0x00]
+    checksum = 0
+    for b in packet:
+        checksum ^= b
+    packet.append(checksum)
+    return Packet.from_bytes(bytes(packet))
+
+def create_set_led_mode(mode=0):
+    """
+    Create an 8-byte packet to set led mode for I2C transfer.
+    Packet format:
+    [0x02, 0x00, Mode, 0x00, 0x00, 0x00, 0x00, checksum]
+    - 0x02: Command for led mode
+    - 0x00: Target/channel (set as needed)
+    - Wagging: 0x00 = standard, 0x01 = rot, 0x02 = rainbow
+    - checksum: XOR of bytes 0-6
+    """
+    packet = [0x02, 0x00, mode & 0xFF, 0x00, 0x00, 0x00, 0x00]
+    checksum = 0
+    for b in packet:
+        checksum ^= b
+    packet.append(checksum)
+    return Packet.from_bytes(bytes(packet))
+
+