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mrudang-vora/CalculateCRC16.py

Last active May 10, 2024 15:49
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Python: CRC 16 ITU calculation
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CalculateCRC16.py
#Working example: http://pythonfiddle.com/crc-16-calculation
def GetCrc16(strHexData):
crc16tab = (
0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78,
)
fcs = int("FFFF",16)
i = 0
while i < len(strHexData):
strHexNumber = strHexData[i:i+2]
#print("str "+strHexNumber)
intNumber = int(strHexNumber,16)
crc16tabIndex = (fcs ^ intNumber) & int("FF",16)
fcs = (fcs >> 8) ^ crc16tab[crc16tabIndex]
i = i + 2
return fcs^0xffff
def GetFormattedHex(intNum, lenOfHexString):
return format(intNum, "0" + str(lenOfHexString) + "x")
#Call above function
requestData = "05010003"
lengthOfHexCRC = 4
strChecksum = GetFormattedHex(GetCrc16(requestData), lengthOfHexCRC)
print(strChecksum)
@eric-lancelot
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eric-lancelot commented Apr 4, 2024 •
edited
Loading

Hi everyone I have tried using it and i got this error which i have been battling for 3 days straight any help

Traceback (most recent call last): File "/home/fms-socket-scripts/wetrack_socket.py", line 147, in <module> packet_info = extract_packet_info(TrackerData) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/fms-socket-scripts/wetrack_socket.py", line 121, in extract_packet_info server_error_check = binascii.hexlify(GetCrc16(crc_data)).decode() ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ TypeError: a bytes-like object is required, not 'int'

here is my code

import socket
import binascii

Function to calculate CRC-ITU (CRC-16-CCITT-FALSE) error check

def crc_itu(data):
crc = 0xFFFF
polynomial = 0x1021

for byte in data:
    crc ^= (byte << 8)

    for _ in range(8):
        if crc & 0x8000:
            crc = ((crc << 1) ^ polynomial) & 0xFFFF
        else:
            crc = (crc << 1) & 0xFFFF

return crc.to_bytes(2, byteorder='big')

def GetCrc16(strHexData):
crc16tab = (
0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78,
)
fcs = int("FFFF",16)
i = 0
while i < len(strHexData):
strHexNumber = strHexData[i:i+2]
#print("str "+strHexNumber)
intNumber = int(strHexNumber,16)
crc16tabIndex = (fcs ^ intNumber) & int("FF",16)
fcs = (fcs >> 8) ^ crc16tab[crc16tabIndex]
i = i + 2
return fcs^0xffff

Set timezone to Africa/Nairobi

Create a TCP server socket

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind((my_server_ip, 3139))
server.listen(1)

print("Waiting for connection...")

while True:
# Accept a client connection
socket_client, _ = server.accept()
print("Connection established.")

# Receive data from the client
encoded_data = socket_client.recv(1500)
TrackerData = binascii.hexlify(encoded_data).decode()

print("Received: ", TrackerData)

def construct_reply_packet():
# Reply packet format according to GT06N protocol
    reply_packet = b'\x78\x78'  # Header
    reply_packet += b'\x05'  # Packet length
    reply_packet += b'\x01'  # Packet type (Login Reply)
    reply_packet += b'\x00\x00\x00\x00\x01'  # Serial Number (example: 0x0000000001)
    reply_packet += b'\x01'  # Error Check
    reply_packet += b'\x0D\x0A'  # stopbit
    
    return reply_packet


def extract_packet_info(packet):
    # Start Bit
    start_bit = packet[:4]

    # Packet Length
    packet_length = packet[4:6]

    # Protocol Number
    protocol_number = packet[6:8]

    # Terminal ID
    terminal_id = packet[8:24]

    # Information Serial Number
    info_serial_number = packet[24:28]

    # Error Check
    error_check = packet[28:32]

    # Stop Bit
    stop_bit = packet[32:]

    crc_data = packet[4:28]  # Packet Length to Information Serial Number (inclusive)
    server_error_check = binascii.hexlify(GetCrc16(crc_data)).decode()
    
    print("Server Error Check val :", server_error_check)

    reply_packet = f"7878{packet_length}{protocol_number}{info_serial_number}{server_error_check}0d0a"
    server_response_packet = binascii.unhexlify(reply_packet)

    print("Server Reply: ", reply_packet)
    print("Server Reply Packet", server_response_packet)

    socket_client.sendall(server_response_packet)

    return {
        "Start Bit": start_bit,
        "Packet Length": packet_length,
        "Protocol Number": protocol_number,
        "Terminal ID": terminal_id,
        "Information Serial Number": info_serial_number,
        "Error Check": error_check,
        "Stop Bit": stop_bit
    }

# Example packet
packet = "78780d01086578405499767400054d5f0d0a"

# Extract information from the packet
packet_info = extract_packet_info(TrackerData)

# Display extracted information
for key, value in packet_info.items():
    print(f"{key}: {value}")

# Close the connection
socket_client.close()

server.close()

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