openamp – provides standard Asymmetric Multiprocessing (AMP) support — MicroPython latest documentation (original) (raw)

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The openamp module provides a standard inter-processor communications infrastructure for MicroPython. The module handles all of the details of OpenAMP, such as setting up the shared resource table, initializing vrings, etc. It provides an API for using the RPMsg bus infrastructure with the Endpoint class, and provides processor Life Cycle Management (LCM) support, such as loading firmware and starting and stopping a remote core, via the RemoteProc class.

Example usage:

import openamp

def ept_recv_callback(src, data): print("Received message on endpoint", data)

Create a new RPMsg endpoint to communicate with the remote core.

ept = openamp.Endpoint("vuart-channel", callback=ept_recv_callback)

Create a RemoteProc object, load its firmware and start it.

rproc = openamp.RemoteProc("virtual_uart.elf") # Or entry point address (ex 0x081E0000) rproc.start()

while True: if ept.is_ready(): ept.send("data")

Functions¶

openamp.new_service_callback(ns_callback)¶

Set the new service callback.

The ns_callback argument is a function that will be called when the remote processor announces new services. At that point the host processor can choose to create the announced endpoint, if this particular service is supported, or ignore it if it’s not. If this function is not set, the host processor should first register the endpoint locally, and it will be automatically bound when the remote announces the service.

Endpoint class¶

class openamp.Endpoint(name, callback, src=ENDPOINT_ADDR_ANY, dest=ENDPOINT_ADDR_ANY)¶

Construct a new RPMsg Endpoint. An endpoint is a bidirectional communication channel between two cores.

Arguments are:

• name is the name of the endpoint.
• callback is a function that is called when the endpoint receives data with the source address of the remote point, and the data as bytes passed by reference.
• src is the endpoint source address. If none is provided one will be assigned to the endpoint by the library.
• dest is the endpoint destination address. If the endpoint is created from the new_service_callback, this must be provided and it must match the remote endpoint’s source address. If the endpoint is registered locally, before the announcement, the destination address will be assigned by the library when the endpoint is bound.

Endpoint.deinit()¶

Destroy the endpoint and release all of its resources.

Endpoint.is_ready()¶

Returns True if the endpoint is ready to send (i.e., has both a source and destination addresses)

Endpoint.send(src=-1, dest=-1, timeout=-1)¶

Send a message to the remote processor over this endpoint.

Arguments are:

• src is the source endpoint address of the message. If none is provided, the source address the endpoint is bound to is used.
• dest is the destination endpoint address of the message. If none is provided, the destination address the endpoint is bound to is used.
• timeout specifies the time in milliseconds to wait for a free buffer. By default the function is blocking.

RemoteProc class¶

class openamp.RemoteProc(entry)¶

The RemoteProc object provides processor Life Cycle Management (LCM) support, such as loading firmware, starting and stopping a remote core.

The entry argument can be a path to firmware image, in which case the firmware is loaded from file to its target memory, or an entry point address, in which case the firmware must be loaded already at the given address.

RemoteProc.start()¶

Starts the remote processor.

RemoteProc.stop()¶

Stops the remote processor. The exact behavior is platform-dependent. On the STM32H7 for example it’s not possible to stop and then restart the Cortex-M4 core, so a complete system reset is performed on a call to this function.

RemoteProc.shutdown()¶

Shutdown stops the remote processor and releases all of its resources. The exact behavior is platform-dependent, however typically it disables power and clocks to the remote core. This function is also used as the finaliser (i.e., called when RemoteProc object is collected). Note that on the STM32H7, it’s not possible to stop and then restart the Cortex-M4 core, so a complete system reset is performed on a call to this function.