config.py

import datetime
import sys
import struct
import json

# global constants
IP_ADDRESS = ""        # dafault IP
PORT = 35001           # new port used in PSAS server-client example
#PORT = 36000          # old port used in PSAS server-client example
PACKET_SIZE = 4096     # maximum packet size to receive
TIMEOUT = 0.1          # backend to frontend update frequency

# debugging
BAD_DEBUG_ONLY = False  # Show only debug information for bad cases
DEBUG = (sys.argv[1:] == ['-d'])
PRINT_CHAR_FOR_ARRIVING_PACKETS = False
PRINT_CHAR_FOR_BACK_TO_FRONT_UPDATE = False

# packet header
SEQUENCE_LENGTH = 4    # packet sequence field length in bytes

# message header format
FIELD_ID_LENGTH = 4     # message field ID (message type ID) length in bytes
TIMESTAMP_LENGTH = 6    # message timestamp length in bytes
DATA_LENGTH_LENGTH = 2  # message data-length length in bytes
HEADER_LENGTH = FIELD_ID_LENGTH + TIMESTAMP_LENGTH + DATA_LENGTH_LENGTH
FIELD_ID_OFFSET = 0
TIMESTAMP_OFFSET = FIELD_ID_OFFSET + FIELD_ID_LENGTH
DATA_LENGTH_OFFSET = TIMESTAMP_OFFSET + TIMESTAMP_LENGTH
DATA_OFFSET = DATA_LENGTH_OFFSET + DATA_LENGTH_LENGTH

# log filename format
PACKET_LOG_FILENAME = datetime.datetime.now().strftime(
    "log/log_%Y.%m.%d_%H-%M-%S")
VALIDATION_LOG_FILENAME = datetime.datetime.now().strftime(
    "log/data_validation_%Y.%m.%d_%H-%M-%S.txt")
MESSAGES_LOG_FILENAME = datetime.datetime.now().strftime(
    "log/messages_%Y.%m.%d_%H-%M-%S.json")

# units conversion
MILLI = 0.001
MICRO = 0.000001
NANO = 0.000000001
GFORCE_EQ_X_MPS2 = 9.80665    # g-force equals 9.81 meters per second squared
GAUSS_EQ_X_TESLA = 0.0001     # gauss equals 0.0001 teslas
KELVIN_MINUS_CELSIUS = 273.0  # (K = C + 273) equivalent to (K - C = 273)

# message format
delimiter = struct.Struct('!4sLH')
gps1_struct = struct.Struct("<BBH 3d 5f HH"),  # GPS BIN1
                    # more details about GPS format here:
                    # http://www.hemispheregps.com/gpsreference/Bin1.htm
message_type = {
    'SEQN':     delimiter,                      # packet log separator
    'GPS\x01':  struct.Struct("<BBH 3d 5f HH"),
    'GPS1':     struct.Struct("<BBH 3d 5f HH"),    
    'ADIS':     struct.Struct("<12h"),          # ADIS16405 IMU
    'MPU9':     struct.Struct(">7H"),           # MPU9150 IMU
    'MPL3':     struct.Struct(">2L"),           # MPL3115A2 Pressure Sensor
    'ROLL':     struct.Struct("<HB")            # ROLL computer data
}

# this line must be in the end of this file
import debug