zbus Proxy agent - IPC

Overview

This sample demonstrates zbus proxy agent communication on multi-core platforms. The sample implements a request-response pattern where:

The application CPU acts as a requester, publishing requests on a channel and receiving responses on a shadow channel
The remote CPU acts as a responder, receiving requests on a shadow channel and publishing responses on a channel
IPC proxy agents automatically synchronize channel data between CPU domains

Each domain defines its own proxy agent and channels.

The proxy agents are defined with ZBUS_PROXY_AGENT_DEFINE
Channels are defined with ZBUS_CHAN_DEFINE and added to proxy agents with ZBUS_PROXY_ADD_CHAN
Shadow channels are defined with ZBUS_SHADOW_CHAN_DEFINE and automatically mirror channels from other domains
Shared data structures (for example, struct transfer_data) are defined separately in each domain’s source code but must remain layout-compatible between domains

This architecture enables message passing between different CPU cores while maintaining zbus’s publish-subscribe structure across domain boundaries.

Building and Running

This sample uses sysbuild for multi-core platforms. Use the test configurations from sample.yaml:

# From the root of the zephyr repository
west build -b nrf54h20dk/nrf54h20/cpuapp -T sample.zbus.proxy_agent_ipc.nrf54h20_cpuapp_cpurad .

Supported platforms and CPU combinations:

nRF54H20: CPUAPP + CPURAD

nRF54L15: CPUAPP + CPUFLPR

nRF54LM20: CPUAPP + CPUFLPR

nRF5340: CPUAPP + CPUNET

Use -T <test_name> with the corresponding test from sample.yaml to build for different configurations.

Sample Output

Application CPU Output

*** Booting Zephyr OS build v4.3.0-8932-g8ad7a29c8069 ***
main: ZBUS Proxy agent IPC Forwarder Sample Application
main: Requesting on channel request_channel, listening on channel response_channel
main: Published on channel request_channel. Test Value=1
main: Received message on channel response_channel. Test Value=2
main: Published on channel request_channel. Test Value=2
main: Received message on channel response_channel. Test Value=3

Remote CPU Output

*** Booting Zephyr OS build v4.3.0-8932-g8ad7a29c8069 ***
main: ZBUS Proxy agent IPC Forwarder Sample Application
main: Listening for requests on channel request_channel, responding on channel response_channel
main: Received message on channel request_channel. Test Value=1
main: Sending response: Test Value=2
main: Response published on channel response_channel
main: Received message on channel request_channel. Test Value=2
main: Sending response: Test Value=3
main: Response published on channel response_channel