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Introduce Dxl packet mocking logic

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Simon Alibert 2025-03-19 18:57:29 +01:00
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commit 794f6e00fc
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import abc
import random
from typing import Callable
import dynamixel_sdk as dxl
import serial
from mock_serial import MockSerial
from lerobot.common.motors.dynamixel.dynamixel import X_SERIES_CONTROL_TABLE
# https://emanual.robotis.com/docs/en/dxl/crc/
DXL_CRC_TABLE = [
0x0000, 0x8005, 0x800F, 0x000A, 0x801B, 0x001E, 0x0014,
0x8011, 0x8033, 0x0036, 0x003C, 0x8039, 0x0028, 0x802D,
0x8027, 0x0022, 0x8063, 0x0066, 0x006C, 0x8069, 0x0078,
0x807D, 0x8077, 0x0072, 0x0050, 0x8055, 0x805F, 0x005A,
0x804B, 0x004E, 0x0044, 0x8041, 0x80C3, 0x00C6, 0x00CC,
0x80C9, 0x00D8, 0x80DD, 0x80D7, 0x00D2, 0x00F0, 0x80F5,
0x80FF, 0x00FA, 0x80EB, 0x00EE, 0x00E4, 0x80E1, 0x00A0,
0x80A5, 0x80AF, 0x00AA, 0x80BB, 0x00BE, 0x00B4, 0x80B1,
0x8093, 0x0096, 0x009C, 0x8099, 0x0088, 0x808D, 0x8087,
0x0082, 0x8183, 0x0186, 0x018C, 0x8189, 0x0198, 0x819D,
0x8197, 0x0192, 0x01B0, 0x81B5, 0x81BF, 0x01BA, 0x81AB,
0x01AE, 0x01A4, 0x81A1, 0x01E0, 0x81E5, 0x81EF, 0x01EA,
0x81FB, 0x01FE, 0x01F4, 0x81F1, 0x81D3, 0x01D6, 0x01DC,
0x81D9, 0x01C8, 0x81CD, 0x81C7, 0x01C2, 0x0140, 0x8145,
0x814F, 0x014A, 0x815B, 0x015E, 0x0154, 0x8151, 0x8173,
0x0176, 0x017C, 0x8179, 0x0168, 0x816D, 0x8167, 0x0162,
0x8123, 0x0126, 0x012C, 0x8129, 0x0138, 0x813D, 0x8137,
0x0132, 0x0110, 0x8115, 0x811F, 0x011A, 0x810B, 0x010E,
0x0104, 0x8101, 0x8303, 0x0306, 0x030C, 0x8309, 0x0318,
0x831D, 0x8317, 0x0312, 0x0330, 0x8335, 0x833F, 0x033A,
0x832B, 0x032E, 0x0324, 0x8321, 0x0360, 0x8365, 0x836F,
0x036A, 0x837B, 0x037E, 0x0374, 0x8371, 0x8353, 0x0356,
0x035C, 0x8359, 0x0348, 0x834D, 0x8347, 0x0342, 0x03C0,
0x83C5, 0x83CF, 0x03CA, 0x83DB, 0x03DE, 0x03D4, 0x83D1,
0x83F3, 0x03F6, 0x03FC, 0x83F9, 0x03E8, 0x83ED, 0x83E7,
0x03E2, 0x83A3, 0x03A6, 0x03AC, 0x83A9, 0x03B8, 0x83BD,
0x83B7, 0x03B2, 0x0390, 0x8395, 0x839F, 0x039A, 0x838B,
0x038E, 0x0384, 0x8381, 0x0280, 0x8285, 0x828F, 0x028A,
0x829B, 0x029E, 0x0294, 0x8291, 0x82B3, 0x02B6, 0x02BC,
0x82B9, 0x02A8, 0x82AD, 0x82A7, 0x02A2, 0x82E3, 0x02E6,
0x02EC, 0x82E9, 0x02F8, 0x82FD, 0x82F7, 0x02F2, 0x02D0,
0x82D5, 0x82DF, 0x02DA, 0x82CB, 0x02CE, 0x02C4, 0x82C1,
0x8243, 0x0246, 0x024C, 0x8249, 0x0258, 0x825D, 0x8257,
0x0252, 0x0270, 0x8275, 0x827F, 0x027A, 0x826B, 0x026E,
0x0264, 0x8261, 0x0220, 0x8225, 0x822F, 0x022A, 0x823B,
0x023E, 0x0234, 0x8231, 0x8213, 0x0216, 0x021C, 0x8219,
0x0208, 0x820D, 0x8207, 0x0202
] # fmt: skip
# https://emanual.robotis.com/docs/en/dxl/protocol2/#instruction
INSTRUCTION_TYPES = {
"Ping": 0x01, # Checks whether the Packet has arrived at a device with the same ID as the specified packet ID
"Read": 0x02, # Read data from the Device
"Write": 0x03, # Write data to the Device
"Reg_Write": 0x04, # Register the Instruction Packet in standby status; Packet can later be executed using the Action command
"Action": 0x05, # Executes a Packet that was registered beforehand using Reg Write
"Factory_Reset": 0x06, # Resets the Control Table to its initial factory default settings
"Reboot": 0x08, # Reboot the Device
"Clear": 0x10, # Reset certain information stored in memory
"Control_Table_Backup": 0x20, # Store current Control Table status data to a Backup or to restore backup EEPROM data.
"Status": 0x55, # Return packet sent following the execution of an Instruction Packet
"Sync_Read": 0x82, # Read data from multiple devices with the same Address with the same length at once
"Sync_Write": 0x83, # Write data to multiple devices with the same Address with the same length at once
"Fast_Sync_Read": 0x8A, # Read data from multiple devices with the same Address with the same length at once
"Bulk_Read": 0x92, # Read data from multiple devices with different Addresses with different lengths at once
"Bulk_Write": 0x93, # Write data to multiple devices with different Addresses with different lengths at once
"Fast_Bulk_Read": 0x9A, # Read data from multiple devices with different Addresses with different lengths at once
} # fmt: skip
# https://emanual.robotis.com/docs/en/dxl/protocol2/#error
STATUS_TYPE = {
"Success": 0x00, # No error
"Result_Fail": 0x01, # Failed to process the sent Instruction Packet
"Instruction_Error": 0x02, # An undefined Instruction has been usedAction has been used without Reg Write
"CRC_Error": 0x03, # The CRC of the sent Packet does not match the expected value
"Data_Range_Error": 0x04, # Data to be written to the specified Address is outside the range of the minimum/maximum value
"Data_Length_Error": 0x05, # Attempted to write Data that is shorter than the required data length of the specified Address
# (ex: when you attempt to only use 2 bytes of a register that has been defined as 4 bytes)
"Data_Limit_Error": 0x06, # Data to be written to the specified Address is outside of the configured Limit value
"Access_Error": 0x07, # Attempted to write a value to an Address that is Read Only or has not been defined
# Attempted to read a value from an Address that is Write Only or has not been defined
# Attempted to write a value to an EEPROM register while Torque was Enabled.
} # fmt: skip
class MockDynamixelPacketv2(abc.ABC):
@staticmethod
def _compute_crc(crc_accum: int, data_blk: list[int], data_blk_size: int) -> int:
for j in range(data_blk_size):
i = ((crc_accum >> 8) ^ data_blk[j]) & 0xFF
crc_accum = ((crc_accum << 8) ^ DXL_CRC_TABLE[i]) & 0xFFFF
return crc_accum
@classmethod
def build(cls, dxl_id: int, params: list[int], *args, **kwargs) -> bytes:
packet = cls._build(dxl_id, params, *args, **kwargs)
crc = cls._compute_crc(0, packet, len(packet) - 2)
packet[-2] = crc & 0xFF # lower byte
packet[-1] = (crc >> 8) & 0xFF # upper byte
return bytes(packet)
@abc.abstractclassmethod
def _build(cls, dxl_id: int, params: list[int], *args, **kwargs):
pass
class MockInstructionPacket(MockDynamixelPacketv2):
"""
Helper class to build valid Dynamixel Protocol 2.0 Instruction Packets with correct CRC.
Protocol 2.0 Instruction Packet structure
(from https://emanual.robotis.com/docs/en/dxl/protocol2/#instruction-packet)
0xFF 0xFF 0xFD 0x00 # 4-byte header
<servo_id> # typically 0x01
<length L> <length H> # 2-byte length of (instruction+error+params+CRC)
<instruction> # instruction type
<parameters...> # for a 4-byte read, we have 4 param bytes
<crc_low> <crc_high> # 16-bit CRC
"""
@classmethod
def _build(cls, dxl_id: int, params: list[int], instruct_type: str):
instruct_value = INSTRUCTION_TYPES[instruct_type]
# For Protocol 2.0, "length" = (number_of_params + 3),
# where:
# +1 is for <instruction> byte,
# +2 is for the CRC at the end.
# The official Dynamixel SDK sometimes uses (+7) logic for sync reads
# because it includes special sub-parameters. But at core:
# length = (instruction byte) + (len(params)) + (CRC16 =2).
packet_length = len(params) + 3
return bytearray(
[
0xFF, 0xFF, 0xFD, 0x00, # header
dxl_id, # servo id
packet_length & 0xFF, # length_l
(packet_length >> 8) & 0xFF, # length_h
instruct_value, # instruction type
*params, # data bytes
0x00, 0x00 # placeholder for CRC
]
) # fmt: skip
@classmethod
def sync_read(
cls,
dxl_ids: list[int],
start_address: int,
data_length: int,
) -> bytes:
"""
Helper method to build a "Sync Read" broadcast instruction.
The official SDK might add some “stuffing” or check param_length,
but this is enough for basic compliance if you want a raw packet.
The parameters for Sync Read (Protocol 2.0) are:
param[0] = start_address L
param[1] = start_address H
param[2] = data_length L
param[3] = data_length H
param[4+] = motor IDs to read from
"""
# Example param: [LowAddr, HighAddr, LowLen, HighLen, ID1, ID2, ...]
params = [
(start_address & 0xFF),
((start_address >> 8) & 0xFF),
(data_length & 0xFF),
((data_length >> 8) & 0xFF),
] + dxl_ids
# broadcast ID: 0xFE
return cls.build(dxl_id=0xFE, instruct_type="Sync_Read", params=params)
class MockStatusPacket(MockDynamixelPacketv2):
"""
Helper class to build valid Dynamixel Protocol 2.0 Status Packets with correct CRC.
Protocol 2.0 Status Packet structure
(from https://emanual.robotis.com/docs/en/dxl/protocol2/#status-packet)
0xFF 0xFF 0xFD 0x00 # 4-byte header
<servo_id> # typically 0x01
<length L> <length H> # 2-byte length of (instruction+error+params+CRC)
0x55 # instruction = 0x55 means "status packet"
<error> # 0 if no error
<parameters...> # for a 4-byte read, we have 4 param bytes
<crc_low> <crc_high> # 16-bit CRC
"""
@classmethod
def _build(cls, dxl_id: int, params: list[int], status: str = "Success") -> bytearray:
status_byte = STATUS_TYPE[status]
return bytearray(
[
0xFF, 0xFF, 0xFD, 0x00, # header
dxl_id, # servo id
0x08, 0x00, # length_l, length_h = 8
0x55, # instruction = status
status_byte, # status
*params, # data bytes
0x00, 0x00 # placeholder for CRC
]
) # fmt: skip
@classmethod
def present_position(cls, dxl_id: int, pos: int | None = None, min_max_range: tuple = (0, 4095)) -> bytes:
"""Builds a 'Present_Position' packet.
Args:
pos (int | None, optional): Desired 'Present_Position'. If None, it will use a random value in the
min_max_range. Defaults to None.
min_max_range (tuple, optional): Min/max range to generate the position values used for when 'pos'
is None. Note that the bounds are included in the range. Defaults to (0, 4095).
Returns:
bytes: The raw 'Present_Position' status packet ready to be sent through serial.
"""
pos = random.randint(*min_max_range) if pos is None else pos
# [lower pos 8 bits, higher pos 8 bits, 0, 0]
params = [pos & 0xFF, (pos >> 8) & 0xFF, 0, 0]
return cls.build(dxl_id, params)
class MockPortHandler(dxl.PortHandler):
def setupPort(self, baud): # noqa: N802
if self.is_open:
self.closePort()
self.ser = serial.Serial(
port=self.port_name,
# baudrate=self.baudrate, <- This is forbidden for ttys ports (on macos at least)
# parity = serial.PARITY_ODD,
# stopbits = serial.STOPBITS_TWO,
bytesize=serial.EIGHTBITS,
timeout=0,
)
self.is_open = True
self.ser.reset_input_buffer()
self.tx_time_per_byte = (1000.0 / self.baudrate) * 10.0
return True
class MockMotors(MockSerial):
ctrl_table = X_SERIES_CONTROL_TABLE
def __init__(self, dlx_ids: list[int], default_stubs: bool = True):
super().__init__()
self._ids = dlx_ids
self.open()
if default_stubs:
self._create_stubs("Present_Position")
def _create_stubs(self, data_name: str):
address, length = self.ctrl_table[data_name]
# sync read all motors
sync_read_request_all = MockInstructionPacket.sync_read(self._ids, address, length)
sync_read_response_all = self._create_present_pos_send_fn(self._ids, data_name)
self.stub(
name=f"SyncRead_{data_name}_all",
receive_bytes=sync_read_request_all,
send_fn=sync_read_response_all,
)
# sync read single motors
for idx in self._ids:
sync_read_request_single = MockInstructionPacket.sync_read([idx], address, length)
sync_read_response_single = self._create_present_pos_send_fn([idx], data_name)
self.stub(
name=f"SyncRead_{data_name}_{idx}",
receive_bytes=sync_read_request_single,
send_fn=sync_read_response_single,
)
def _create_present_pos_send_fn(
self, dxl_ids: list[int], data_name: str, num_invalid_try: int | None = None
) -> Callable[[int], bytes]:
# if data_name == "Present_Position":
# packet_generator = MockStatusPacket.present_position
# else:
# # TODO(aliberts): add "Goal_Position"
# raise NotImplementedError
def send_fn(_call_count: int) -> bytes:
if num_invalid_try is not None and num_invalid_try >= _call_count:
return bytes(0)
first_packet = MockStatusPacket.present_position(next(iter(dxl_ids)))
if len(dxl_ids) == 1:
return first_packet
packets = first_packet
for idx in dxl_ids:
packets += MockStatusPacket.present_position(dxl_id=idx)
return packets
return send_fn