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Python example of how to send and receive serial messages from a BaseCam gimbal with SimpleBGC 32-bit controller.
from collections import namedtuple
import serial
import struct
# outgoing CMD_CONTROL - control gimbal movement
ControlData = namedtuple(
'ControlData',
'roll_mode pitch_mode yaw_mode roll_speed roll_angle pitch_speed pitch_angle yaw_speed yaw_angle')
Message = namedtuple(
'Message',
'start_character command_id payload_size header_checksum payload payload_checksum')
def pack_control_data(control_data: ControlData) -> bytes:
return struct.pack('<BBBhhhhhh', *control_data)
def create_message(command_id: int, payload: bytes) -> Message:
payload_size = len(payload)
return Message(start_character=ord('>'),
command_id=command_id,
payload_size=payload_size,
header_checksum=(command_id + payload_size) % 256,
payload=payload,
payload_checksum=sum(payload) % 256)
def pack_message(message: Message) -> bytes:
message_format = '<BBBB{}sB'.format(message.payload_size)
return struct.pack(message_format, *message)
def unpack_message(data: bytes, payload_size: int) -> Message:
message_format = '<BBBB{}sB'.format(payload_size)
return Message._make(struct.unpack(message_format, data))
def read_message(connection: serial.Serial, payload_size: int) -> Message:
# 5 is the length of the header + payload checksum byte
# 1 is the payload size
response_data = connection.read(5 + payload_size)
print('received response', response_data)
return unpack_message(response_data, payload_size)
def rotate_gimbal():
CMD_CONTROL = 67
control_data = ControlData(roll_mode=1, roll_speed=0, roll_angle=0,
pitch_mode=1, pitch_speed=0, pitch_angle=0,
yaw_mode=1, yaw_speed=100, yaw_angle=0)
print('command to send:', control_data)
packed_control_data = pack_control_data(control_data)
print('packed command as payload:', packed_control_data)
message = create_message(CMD_CONTROL, packed_control_data)
print('created message:', message)
packed_message = pack_message(message)
print('packed message:', packed_message)
connection = serial.Serial('/dev/ttyUSB0', baudrate=115200, timeout=10)
print('send packed message:', packed_message)
connection.write(packed_message)
message = read_message(connection, 1)
print('received confirmation:', message)
print('confirmed command with ID:', ord(message.payload))
if __name__ == '__main__':
rotate_gimbal()
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