Specifications

SLAA137A
14 MSP430 Internet Connectivity
• A time-out is exceeded
• An error occurs (network error, connection is reset by the opponent)
The software implements the essential parts of the standards RFC 791, 792 and 793. The most
important function of this stack is DoNetworkStuff(). This function must be called periodically by
the user application. The event handling of the TCP is done here. Different flags are polled in
both the ethernet controller and the MCU. According to the flags, this function branches to the
appropriate event handler. The more often this function is called, the better the performance of
the TCP is. A special set of event handlers is the user events. They are triggered by calling one
of the stack functions directly by the application. These functions are described in Section 4.3.
Read RxEvent Register of CS8900A
Frame Received?
Demultiplexing
(DA = Broadcast / Individual)
Timer Event Occured?
Handle Retransmission or Timeout Error,
Close Connection if Requested.
Adapt the TCP State Machine According to
Global Flags.
TxFrame2 Buffer Send Requested?
Request Memory in LAN Controller and Send
the TxFrame2 Buffer.
TxFrame1 Buffer Send Requested?
Request Memory in LAN Controller and Send
the TxFrame1 Buffer.
Yes
Yes
Yes
Yes
No
No
No
No
Figure 6. DoNetworkStuff() Flowchart