Bluegiga IWIP3G - IWRAP - IPHONE 3G, Руководство пользователя

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normal mode, the data is stored to small iWRAP buffers and received when the
connections become active (data mode of the connection enabled).
The next figure illustrates the host-iWRAP-host communications in multiplexing mode.
Host UART
<0xBF> <0xFF> <0x00> <2> <AT> <0x00>
<0xBF> <0xFF> <0x00> <2> <OK> <0x00>
Figure 4: Host-iWRAP-Host communication
The figure below illustrates host-iWRAP-remote device communication when multiplexing
mode is in use. The key thing is that the remote device does not need to know anything
about the multiplexing communication and frame format, but it sees the connection as a
standard
Bluetooth connection.
Host UART
Bluetooth link
<0xBF> <0x00> <0x00> <len> <Data> <0xFF>
<0xBF> <0x00> <0x00> <len> <Data> <0xFF>
Data
Data
Figure 5: Host-iWRAP-remote device communications
At the moment, four (4) simultaneous connections can be used in multiplexing mode.
Tips:
In MUX mode the processor of the module is highly utilized and on the edge of its
performance. This may be seen as a instability of
Bluetooth connections, especially if 3 or
more connections are used or data rate is high. There are however a few tricks how the
stability of the
Bluetooth connections can be improved:
1. Use SNIFF mode: Using sniff mode reduces the rate the master device needs to poll
the active connections are leaves more time for the processor to parse or generate
the multiplexing protocol. Therefore as aggressive as possible sniff mode should be
used.
2. Optimize Bluetooth packet size by using MTU option in CALL command: Using
smaller Bluetooth packet size improves the multiplexing performance.
On the next page, there is a simple C-code example on how to create a simple
multiplexing frame containing an iWRAP command.