Thomas Ales [M S E]
95 lines
3.4 KiB
Python
95 lines
3.4 KiB
Python
'''
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SRAS Serial Communication Tools
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Thomas Ales | Feb 2026
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Version 1
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'''
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from threading import Thread
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from queue import Queue
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import serial
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import struct
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import time
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class SerialSnooper(Thread):
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def __init__(self, _port, _spd):
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super().__init__()
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self.serial_connection = None
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self.serial_port = _port
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self.serial_speed = _spd
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self.am_listening = False
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self.rx_msg_queue = Queue()
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def run(self):
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'''
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run() - Starts up the serial listener, checks if the port was
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opened successfully, and if so begins
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listening for APT messages.
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'''
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self.serial_connection = serial.Serial(port=self.serial_port,
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baudrate=self.serial_speed,
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rtscts=True, timeout=0.05)
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if self.serial_connection.is_open is True:
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# Send disconnect to stop any ongoing auto-updates from
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# a previous session
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for addr in [0x11, 0x21, 0x22]:
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disconnect_msg = struct.pack('<HBBBB', 0x0002,
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0x00, 0x00, addr, 0x01)
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self.serial_connection.write(disconnect_msg)
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# Wait for controller to process, then flush everything
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time.sleep(0.2)
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self.serial_connection.reset_output_buffer()
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self.serial_connection.reset_input_buffer()
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# Discard any remaining data that arrived
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time.sleep(0.1)
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if self.serial_connection.in_waiting > 0:
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self.serial_connection.read(self.serial_connection.in_waiting)
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self.am_listening = True
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_rxbuf = bytearray()
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while self.am_listening is True:
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try:
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# Read whatever is available (or wait up to timeout)
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_chunk = self.serial_connection.read(
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max(1, self.serial_connection.in_waiting))
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if _chunk:
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_rxbuf.extend(_chunk)
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# Process complete messages from the buffer
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while len(_rxbuf) >= 6:
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# Check if this is a long message (bit 7 of byte 4)
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if _rxbuf[4] & 0x80:
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_msglen = struct.unpack("<H", _rxbuf[2:4])[0]
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total = 6 + _msglen
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if len(_rxbuf) < total:
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break # need more bytes
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_packet = bytes(_rxbuf[:total])
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del _rxbuf[:total]
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else:
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_packet = bytes(_rxbuf[:6])
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del _rxbuf[:6]
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self.rx_msg_queue.put_nowait(_packet)
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except (serial.SerialException, TypeError, OSError):
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break
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return
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def stop(self):
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'''
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stop() - Signals the listener loop to stop. Call join() after
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this to wait for the thread to exit, then call close() to
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release the serial port.
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'''
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self.am_listening = False
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def close(self):
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'''
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close() - Closes the serial port. Only call after the
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thread has been joined.
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'''
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if self.serial_connection and self.serial_connection.is_open:
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self.serial_connection.close()
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