DLE Encoder for Python

This encoder provides a simple ASCII transport layer for serial data. It uses the C0 and C1 ASCII control characters for this. You can find a corresponding C++ implementation here. This encoder supports two modes:

Escaped mode

The encoded stream starts with a STX marker and ends with an ETX marker. STX and ETX occurrences in the stream are escaped and internally encoded as well so the receiver side can simply check for STX and ETX markers as frame delimiters. When using a strictly char based reception of packets encoded with DLE, STX can be used to notify a reader that actual data will start to arrive while ETX can be used to notify the reader that the data has ended.

Example:

[0, STX, DLE] -> [STX, 0, 0, DLE, STX + 0x40, DLE, DLE, ETX]

Non-escaped mode

The encoded stream starts with DLE STX and ends with DLE ETX. All DLE occurrences in the stream are escaped with DLE. If the receiver detects a DLE char, it needs to read the next char to determine whether a start (STX) or end (ETX) of a frame has been detected.

Example:

[0, STX, DLE] -> [DLE, STX, 0, DLE, STX, DLE, DLE, DLE, ETX]

Install

You can install this package from PyPI

Linux:

python3 -m pip install dle-encoder

Windows:

py -m pip install dle-encoder

Examples

import dle_encoder

encoder = dle_encoder.DleEncoder()
test_array = bytearray([1, 2, 3])
encoded = encoder.encode(test_array)
retval, decoded, bytes_decoded = encoder.decode(encoded)

print(test_array)
print(encoded)
print(decoded)

The non-escaped mode can be used by passing escape_stx_etc=False to the DleEncoder constructor.

License

Copyright 2019-2021 Robin Mueller, KSat e.V. Stuttgart

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.