Asyncio implementation of ISO-TP (ISO 15765-2)
Project description
This package implements ISO-TP over CAN as an asyncio transport layer, enabling simultaneous receiving and transmitting messages with any number of connections.
Raw CAN communication uses python-can which offers compatibility for many different CAN interfaces and operating systems.
If SocketCAN ISO-TP module is loaded and Python 3.7+ is used, the transport is delegated to the kernel if possible for better timing performance. Use the ‘socketcan’ interface. If unsuccessful, raw CAN will be used as fallback.
The isotpserver from can-utils can also be used to bridge a SocketCAN ISO-TP connection over TCP/IP. Use the ‘isotpserver’ interface and ‘host:port’ as channel.
Why asynchronous?
Asynchronous programming simplifies some possible use-cases:
Full duplex receiving and transmitting on a single connection.
Communicate on multiple connections simultaneously.
Functional addressing where one request is sent out and all nodes respond, then processing the responses as they arrive.
Implementing or simulating multiple servers.
No threads need to be handled with all the locking mechanisms required by it.
Installation
Install from PyPI:
$ pip install aioisotp==0.1.1
Documentation
A basic documentation can be built using Sphinx:
$ python setup.py build_sphinx
Quick start
Here is an example of an echo server implemented using a callback based protocol and a client implemented as sequencial reader and writer streams.
import asyncio
import aioisotp
class EchoServer(asyncio.Protocol):
def connection_made(self, transport):
self.transport = transport
def data_received(self, data):
# Echo back the same data
self.transport.write(data)
async def main():
network = aioisotp.ISOTPNetwork('vcan0',
interface='virtual',
receive_own_messages=True)
with network.open():
# A server that uses a protocol
transport, protocol = await network.create_connection(
EchoServer, 0x1CDADCF9, 0x1CDAF9DC)
# A client that uses streams
reader, writer = await network.open_connection(
0x1CDAF9DC, 0x1CDADCF9)
writer.write(b'Hello world!')
response = await reader.read(4095)
assert response == b'Hello world!'
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
UDS
This package is meant to enable the use of other protocols that require ISO-TP. One of the most common is UDS. A third party library like udsoncan or pyvit can be used to encode and decode payloads.
import aioisotp
import udsoncan
...
reader, writer = await network.open_connection(0x1CDAF9DC, 0x1CDADCF9)
# Construct and send request
request = udsoncan.Request(
udsoncan.services.ReadDataByIdentifier, data=b'\xF1\x90')
writer.write(request.get_payload())
# Wait for response and decode the payload
payload = await reader.read(4095)
response = udsoncan.Response.from_payload(payload)
print(response)
print(response.data)
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