L2CAP Implementation in Real-time Devices
Original Post: L2CAP implementation question (eGroups Msg. )
Date: 2000-06-30
Some questions have been asked about the suitability of L2CAP
Messages for real-time/environment devices.Take the L2CA_ConnectReq for example,
the defined primitives states that the message is blocked until the completion
of the task.
Question
An L2CA_ConnectReq may take some time to complete, and
depending on the platform on which the stack runs, this may be undesirable. In
an embedded system with no multitasking OS , the system would appear dead until
control is returned from the function. Is there any way to get around this ?
i.e. If a call to L2CA_ConnectReq was made into the stack and there was no
connection already established between me and the BD_ADDR specified, am I
allowed to return from this call after initiating an HCI_CreateConnection, but
before it is complete?
Answer
The upper interface of L2CAP is only a suggested
interface. It could be implemented as call-back functions, multi-tasking OS
messages or any other method that implements the L2CAP state machine. The
interface you have to be careful about is the TCI-L2CAP interface which must
operate as specified for qualification purposes. But even here, it is the
external connection not the internal connections that must follow the spec. What
is important is to have the correct functionality, how it happens within
the machine is not important.
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