blob: b2555594a0b0edcc54a55a15f281dad33b1d11ee [file] [log] [blame]
.. _module-pw_hdlc-rpc-example:
RPC over HDLC example project
The :ref:`module-pw_hdlc` module includes an example of bringing up a
:ref:`module-pw_rpc` server that can be used to invoke RPCs. The example code
is located at ``pw_hdlc/rpc_example``. This section walks through invoking RPCs
interactively and with a script using the RPC over HDLC example.
These instructions assume the STM32F429i Discovery board, but they work with
any target with :ref:`pw::sys_io <module-pw_sys_io>` implemented.
Getting started guide
1. Set up your board
Connect the board you'll be communicating with. For the Discovery board, connect
the mini USB port, and note which serial device it appears as (e.g.
2. Build Pigweed
Activate the Pigweed environment and run the default build.
.. code-block:: sh
gn gen out
ninja -C out
3. Flash the firmware image
After a successful build, the binary for the example will be located at
Flash this image to your board. If you are using the STM32F429i Discovery Board,
you can flash the image with `OpenOCD <>`_.
.. code-block:: sh
openocd -f targets/stm32f429i_disc1/py/stm32f429i_disc1_utils/openocd_stm32f4xx.cfg \
-c "program out/stm32f429i_disc1_debug/obj/pw_hdlc/rpc_example/bin/rpc_example.elf"
4. Invoke RPCs from in an interactive console
The RPC console uses `IPython <>`_ to make a rich interactive
console for working with pw_rpc. Run the RPC console with the following command,
replacing ``/dev/ttyACM0`` with the correct serial device for your board.
.. code-block:: text
$ python -m pw_system.console --device /dev/ttyACM0
Console for interacting with pw_rpc over HDLC.
To start the console, provide a serial port as the --device argument and paths
or globs for .proto files that define the RPC services to support:
python -m pw_system.console --device /dev/ttyUSB0 --proto-globs pw_rpc/echo.proto
This starts an IPython console for communicating with the connected device. A
few variables are predefined in the interactive console. These include:
rpcs - used to invoke RPCs
device - the serial device used for communication
client - the pw_rpc.Client
An example echo RPC command:"hello!")
In [1]:
RPCs may be accessed through the predefined ``rpcs`` variable. RPCs are
organized by their protocol buffer package and RPC service, as defined in a
.proto file. To call the ``Echo`` method is part of the ``EchoService``, which
is in the ``pw.rpc`` package. To invoke it synchronously, call
.. code-block:: python
In [1]:"Your message here!")
Out[1]: (<Status.OK: 0>, msg: "Your message here!")
5. Invoke RPCs with a script
RPCs may also be invoked from Python scripts. Close the RPC console if it is
running, and execute the example script. Set the --device argument to the
serial port for your device.
.. code-block:: text
$ pw_hdlc/rpc_example/ --device /dev/ttyACM0
The status was Status.OK
The payload was msg: "Hello"
The device says: Goodbye!
Local RPC example project
This example is similar to the above example, except it use socket to
connect server and client running on the host.
1. Build Pigweed
Activate the Pigweed environment and build the code.
.. code-block:: sh
gn gen out
pw watch
2. Start client side and server side
Run pw_rpc client (i.e. use echo.proto)
.. code-block:: sh
python -m pw_system.console path/to/echo.proto -s localhost:33000
Run pw_rpc server
.. code-block:: sh
Then you can invoke RPCs from the interactive console on the client side.