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UBXManager.py
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UBXManager.py
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#!/usr/bin/env python3
"""TODO."""
import threading
from enum import Enum
import sys
class UBXManager(threading.Thread):
"""The NMEA/UBX reader/writer thread."""
class STATE(Enum):
START = 0
NMEA_BODY = 1
NMEA_CHKSUM_1 = 2
NMEA_CHKSUM_2 = 3
UBX_SYNC_CHAR_2 = 4
UBX_CLASS = 5
UBX_ID = 6
UBX_LENGTH_1 = 7
UBX_LENGTH_2 = 8
UBX_PAYLOAD = 9
UBX_CHKSUM_1 = 10
UBX_CHKSUM_2 = 11
def __init__(self, ser, debug=False):
"""Instantiate with serial."""
from UBXMessage import UBXMessage
threading.Thread.__init__(self)
self.ser = ser
self.debug = debug
self._shutDown = False
self.ubx_chksum = UBXMessage.Checksum()
def run(self):
"""Run the parser."""
transitionFrom = [
self._fromSTART,
self._fromNMEA_BODY,
self._fromNMEA_CHKSUM_1,
self._fromNMEA_CHKSUM_2,
self._fromUBX_SYNC_CHAR_2,
self._fromUBX_CLASS,
self._fromUBX_ID,
self._fromUBX_LENGTH_1,
self._fromUBX_LENGTH_2,
self._fromUBX_PAYLOAD,
self._fromUBX_CHKSUM_1,
self._fromUBX_CHKSUM_2,
]
if self.debug:
logfile = open("UBX.log", "wb")
sys.stderr.write("Writing log to UBX.log\n")
self._reset()
while not self._shutDown:
byte = self.ser.read(1)
if self.debug:
logfile.write(byte)
logfile.flush()
self.state = transitionFrom[self.state.value](byte)
def _reset(self):
self.buffer = b''
self.chksum = 0
self.chksum_calc = 0
self.ubx_class = 0
self.ubx_id = 0
self.ubx_length = 0
self.state = UBXManager.STATE.START
self.ubx_chksum.reset()
def _fromSTART(self, byte):
if byte == b'$':
return UBXManager.STATE.NMEA_BODY
elif byte == b'\xb5':
return UBXManager.STATE.UBX_SYNC_CHAR_2
else:
return UBXManager.STATE.START
def _fromNMEA_BODY(self, byte):
if byte == b'*':
return UBXManager.STATE.NMEA_CHKSUM_1
else:
self.buffer += byte
self.chksum_calc ^= ord(byte)
return UBXManager.STATE.NMEA_BODY
def _fromNMEA_CHKSUM_1(self, byte):
try:
self.chksum = int(byte, 16) * 16
except ValueError:
return UBXManager.STATE.START
return UBXManager.STATE.NMEA_CHKSUM_2
def _fromNMEA_CHKSUM_2(self, byte):
try:
self.chksum += int(byte, 16)
except ValueError:
return UBXManager.STATE.START
if self.chksum == self.chksum_calc:
self._onNMEA(self.buffer.decode('ascii'))
else:
self._onNMEAError(
"Incorrect Checksum: {:02X} should be {:02X}"
.format(self.chksum_calc, self.chksum)
)
self._reset()
return UBXManager.STATE.START
def _fromUBX_SYNC_CHAR_2(self, byte):
if byte == b'\x62':
return UBXManager.STATE.UBX_CLASS
else:
return UBXManager.STATE.START
def _fromUBX_CLASS(self, byte):
self.ubx_class = ord(byte)
self.ubx_chksum.update(byte)
return UBXManager.STATE.UBX_ID
def _fromUBX_ID(self, byte):
self.ubx_id = ord(byte)
self.ubx_chksum.update(byte)
return UBXManager.STATE.UBX_LENGTH_1
def _fromUBX_LENGTH_1(self, byte):
self.ubx_length = ord(byte)
self.ubx_chksum.update(byte)
return UBXManager.STATE.UBX_LENGTH_2
def _fromUBX_LENGTH_2(self, byte):
self.ubx_length = self.ubx_length + 256 * ord(byte)
self.ubx_chksum.update(byte)
return UBXManager.STATE.UBX_PAYLOAD
def _fromUBX_PAYLOAD(self, byte):
if self.ubx_length > 0:
self.buffer += byte
self.ubx_length -= 1
self.ubx_chksum.update(byte)
return UBXManager.STATE.UBX_PAYLOAD
else:
self.chksum = 256 * ord(byte) # CK_A shifted left
return UBXManager.STATE.UBX_CHKSUM_1
def _fromUBX_CHKSUM_1(self, byte):
self.chksum += ord(byte) # 256 * CK_A + CK_B
return UBXManager.STATE.UBX_CHKSUM_2
def _fromUBX_CHKSUM_2(self, byte):
if self.chksum == self.ubx_chksum.get():
self._onUBX(self.ubx_class, self.ubx_id, self.buffer)
else:
self._onUBXError(
self.ubx_class,
self.ubx_id,
"Incorrect Checksum: {:04X} should be {:04X}"
.format(self.ubx_chksum.get(), self.chksum)
)
self._reset()
if byte == b'$':
return UBXManager.STATE.NMEA_BODY
elif byte == b'\xb5':
return UBXManager.STATE.UBX_SYNC_CHAR_2
else:
return UBXManager.STATE.START
def _onNMEA(self, buffer):
self.onNMEA(buffer)
def onNMEA(self, buffer):
"""Default handler for good NMEA message."""
print("NMEA: {}".format(buffer))
def _onNMEAError(self, errMsg):
self.onNMEAError(errMsg)
def onNMEAError(self, errMsg):
"""Default handler for faulty NMEA message."""
print("NMEA ERR: {}".format(errMsg))
def _onUBX(self, msgClass, msgId, buffer):
from UBXMessage import parseUBXPayload, formatByteString
try:
obj = parseUBXPayload(msgClass, msgId, buffer)
except Exception as e:
errMsg = "No parse, \"{}\", payload={}".format(
e, formatByteString(buffer))
self.onUBXError(msgClass, msgId, errMsg)
else:
self.onUBX(obj)
def onUBX(self, obj):
"""Default handler for good UBX message."""
print(obj)
def _onUBXError(self, msgClass, msgId, errMsg):
"""Handle an UBX error."""
def onUBXError(self, msgClass, msgId, errMsg):
"""Default handler for faulty or not yet defined UBX message."""
print("UBX ERR {:02X}:{:02X} {}"
.format(msgClass, msgId, errMsg))
def send(self, msg):
"""Send message to ser."""
from UBXMessage import formatByteString
if self.debug:
print("SEND: {}".format(formatByteString(msg)))
self.ser.write(msg)
def shutdown(self):
"""Stop the manger."""
self._shutDown = True