03 - RPC¶

This example illustrates how to create and call RPCs using pw_rpc and pw_console.

Trying out the RPC example¶

Build the test with pw build or pw watch.
Launch the RPC example on a device, or using the simulated device.

STM32F429I_DISC1 (Linux/MacOS)
- Flash rpc_main.elf:
```
pw flash --device STM32-Discovery out/gn/stm32f429i_disc1_stm32cube.size_optimized/obj/examples/03_rpc/bin/rpc_main.elf
```
  Note
  
  We don’t yet have OpenOCD for Windows. See b/300986008 for updates.
Raspberry Pi Pico (RP2404) (Windows/Linux/MacOS)
- Flash ./out/gn/rp2040.size_optimized/obj/examples/03_rpc/rpc_main.uf2:
  1. Reboot the Pico into BOOTSEL mode by holding the bootsel button when plugging into USB.
  2. Copy ./out/gn/rp2040.size_optimized/obj/examples/03_rpc/rpc_main.uf2 to your Pi Pico.
  Note
  
  It is also possible to flash a Pico board with picotool. We will be adding support for that in this repo soon. See b/300321451 for updates.
- Open pw_console.
```
pw console -d /dev/ttyACM0 -b 115200 --token-databases out/gn/stm32f429i_disc1_stm32cube.size_optimized/obj/examples/03_rpc/bin/rpc_main.elf
```
  Tip
  
  On macOS, your device will look like /dev/cu.usbmodem2141403, but will most likely end with a different number.
Simulated device (all platforms)

Start the simulated device with the following command:
```
pw device-sim --sim-binary ./out/gn/host_device_simulator.speed_optimized/obj/examples/03_rpc/bin/rpc_main
```
If using Bazel launch the simulator with bazel run:
```
bazel run //examples/03_rpc:simulator_console
```
In the Python Repl pane, use an RPC to request the device’s UUID.
```
>>> device.rpcs.rpc_example.DeviceInfo.GetUuid()
```
You should see it fail because the device does not yet have a UUID set:
```
(Status.NOT_FOUND, rpc_example.DeviceUuid())
```
In the Device Logs pane, you’ll see a log message like the following:
```
UUID request received, but this device has no UUID yet
```

In the Python Repl pane, set the device’s UUID.

>>> device.rpcs.rpc_example.DeviceInfo.SetUuid(uuid=b'\xab\xcd\ef\x01\x23\x45\x67\x89')

It should succeed with the following response:

(Status.OK, pw.protobuf.Empty())

In the Python Repl pane, use an RPC to request the device’s UUID again.

This time, the device should respond with the UUID you set using the previous command:
```
(Status.OK, rpc_example.DeviceUuid(uuid=b'\xAB\xCD\xEF\x01\x23\x45\x67\x89'))
```
Try setting the UUID to a much longer string of bytes and see what happens!
When you’re finished, you can type quit in the Python Repl pane to exit.