This section describes the differences between IPC APIs of MCU+ SDK and Processor SDK RTOS (PDK). This can be used as migration aid when moving from Processor SDK RTOS (PDK) to MCU+ SDK.

In MCU+ SDK, the IPC APIs are simplified and consolidated into below two APIs

IPC Notify to provide exterme low latency IPC API
- This can be considered as new API that can be used when sub-micro second IPC latency is needed in some hard real-time applications
IPC RPMessage to provide higher level message passing IPC API
- IPC RPMessage replaces both IPC LLD and mailbox LLD from PDK.

API changes

There are changes in functions names, structure names and macro names. The changes in function names are listed below.

PDK	MCU+ SDK	Change Description / Remarks
IPC LLD
IpcInitPrms_init	RPMessage_Params_init, IpcNotify_Params_init	In MCU+ SDK, both IPC notify and IPC rpmsg need to be initialized. SysConfig can be used to simplify the IPC module init.
Ipc_init, RPMessage_init	RPMessage_init, IpcNotify_init	In MCU+ SDK, both IPC notify and IPC rpmsg need to be initialized. SysConfig can be used to simplify the IPC module init.
Ipc_deinit, RPMessage_deInit	RPMessage_deInit, IpcNotify_deInit	In MCU+ SDK, both IPC notify and IPC rpmsg need to be de-initialized. SysConfig can be used to simplify the IPC module init.
RPMessage_lateInit	RPMessage_waitForLinuxReady	API rename
RPMessageParams_init	RPMessage_CreateParams_init	API rename
RPMessage_create	RPMessage_construct	Static alloc friendly API, simplified API
RPMessage_setCallback	NONE	Set callback as part of RPMessage_construct parameters
RPMessage_recv, RPMessage_recvNb	RPMessage_recv	Unified API for blocking as well as non-blocking mode.
RPMessage_send	RPMessage_send	API signature to match RPMessage_recv parameters and also supports timeout
RPMessage_delete	RPMessage_destruct	Static alloc friendly API
RPMessage_unblock	RPMessage_unblock	NO CHANGE
RPMessage_getRemoteEndPt, RPMessage_getRemoteEndPtToken	RPMessage_controlEndPtCallback	Callback based mechanism to listen to announce messages from remote CPUs, to enable NORTOS implementation.
RPMessage_announce	RPMessage_announce	NO CHANGE, except that "ALL" cannot be used to send annoucement to all CPUs, specific CPU ID MUST be used.
RPMessage_getMessageBufferSize, RPMessage_getObjMemRequired, RPMessage_unblockGetRemoteEndPt, Ipc_newMessageIsr, Ipc_mailboxEnableNewMsgInt, Ipc_mailboxDisableNewMsgInt	NONE	NOT needed in MCU+ SDK.
NONE	RPMessage_getLocalEndPt	New APIs to complete the functionality
Mailbox LLD
Mailbox_initParams_init	RPMessage_Params_init, IpcNotify_Params_init	In MCU+ SDK, both IPC notify and IPC rpmsg need to be initialized. SysConfig can be used to simplify the IPC module init.
Mailbox_init	RPMessage_init, IpcNotify_init	In MCU+ SDK, both IPC notify and IPC rpmsg need to be initialized. SysConfig can be used to simplify the IPC module init.
Mailbox_deinit	RPMessage_deInit, IpcNotify_deInit	In MCU+ SDK, both IPC notify and IPC rpmsg need to be de-initialized. SysConfig can be used to simplify the IPC module init.
Mailbox_openParams_init	RPMessage_CreateParams_init	In MCU+ SDK, create a local end point to receive messages from any remote CPU at local CPU
Mailbox_open	RPMessage_construct	In MCU+ SDK, create a local end point to receive messages from any remote CPU at local CPU
Mailbox_write	RPMessage_send	In MCU+ SDK, use this API to send a message to a specific remote CPU and specific end point on that CPU
Mailbox_read	RPMessage_recv	In MCU+ SDK, use this API to receive messages from remote CPUs to the create local end point. The remote CPU and remote CPU end point is returned when the API returns.
Mailbox_readFlush	RPMessage_recv	In MCU+ SDK, explicit flush is not needed and is taken care of in RPMessage_recv.
Mailbox_close	RPMessage_destruct	In MCU+ SDK, use this to close a previously created local end point.
Mailbox_GetMessageCount, Mailbox_getStats, Mailbox_enableInterrupts, Mailbox_disableInterrupts	NONE	NOT needed in MCU+ SDK.
NONE	RPMessage_waitForLinuxReady, RPMessage_controlEndPtCallback, RPMessage_announce,	This APIs can be ignored when migrating from mailbox LLD.
NONE	RPMessage_unblock, RPMessage_getLocalEndPt	These APIs can be useful when writing applications using IPC rpmsg API.

Important Notes

Migration from IPC LLD API

In MCU+ SDK use the IPC RPMessage to get equivalent features of IPC LLD.
MCU+ SDK implements the same rpmsg protocol as IPC LLD. Only the APIs are lot more simplified and enable low memory footprint applications vs PDK.

Migration from Mailbox LLD API

To get equivalent features of mailbox LLD, create one rpmsg end point (equivalent to channel in mailbox LLD) and then use rpmsg APIs to send and receive message packets.
Unlike mailbox LLD, when using IPC RPMessage, one can send a new message even if previous message is not yet read. This is possible when number of message buffers is configured as > 1. In order to not allow sending of new message until previous message is read, set the number of message buffers to 1 during module initialization

API changes

Important Notes

Migration from IPC LLD API

Migration from Mailbox LLD API

See Also