This folder contains several code examples of how to use python4yahdlc.

The code examples work in pairs: send_data_frame.py works with receive_data_frame.py and fsm_endpoint_1.py works with fsm_endpoint_2.py.

To make the two code examples of each pair work together, you need a serial bus of communication. The easiest way to set up a serial bus is to use a virtual one. socat is a great tool for carrying out this task:

socat -d -d pty,raw,echo=0 pty,raw,echo=0

This command will create two virtual devices (e.g. /dev/pts/5 and /dev/pts/6). Everything you write in one will be echoed in the other and vice versa.

These two code examples need pyserial as dependency:

pip install --upgrade pyserial

These two code examples need pyserial and fysom as dependencies:

pip install --upgrade pyserial fysom

fysom is used to define the Finite-State Machines (FSM) of the two endpoints.

The sending FSM endpoint:

    stateDiagram-v2
init --> send_data: connection_ok
init --> init: connection_ko

send_data --> wait_ack: send_ok

wait_ack --> pause: ack_received
wait_ack --> send_data: nack_received
wait_ack --> send_data: timeout
wait_ack --> pause: bad_frame_received

pause --> send_data: timeup

The receiving FSM endpoint:

    stateDiagram-v2
init --> wait_data: connection_ok
init --> init: connection_ko

wait_data --> send_ack: data_ok
wait_data --> send_nack: data_ko

send_ack --> wait_data: ack_sent

send_nack --> wait_data: nack_sent