User's Manual

Class 1 Bluetooth v2.0 Module
User’s Guide
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CONN-GUIDE-BT730_v0.9
8.4.3 nnn GET
This FTP response is used during a GET file operation. See appropriate message sequence charts for
more details. See Table 8-1 for ‘nnn’ values.
8.5 FTP line multiplexing commands
When transferring a file, the single serial interface between the host and the module is used to send and
receive data and commands. In other words, a scheme is required to unambiguously determine when a
byte on the line corresponds to a command or data belonging to a file.
The module uses negotiated multiplexing to achieve this and commands are used to toggle the line
between command and data mode.
This scheme is symmetrical and the commands for toggling the state of the line are relevant for both
direction. The only difference being that the terminator is <cr> in the host to module direction and<crlf> in
the reverse direction.
The commands are described in the following sub sections.
8.5.1 #
This command is used to ask the other end how many bytes of a filename or foldername it will send next.
8.5.2 >
This command is used to inform the other end that it is safe to send the number of bytes belonging to a
filename or foldername as indicated in the most recent # command.
8.5.3 !
This command is used to ask the module/host how many bytes of data it will send next. If the module/host
sends a length value that is too large to handle, it can be rejected by sending the ! command again. This
is because accepting a value implies this end should send a ? prompt to trigger the data phase (See
Section 8.5.4).
8.5.4 ?
This command is used to inform the other end that it is safe to send the number of bytes belonging to
‘data’ phase indicated in the most recent ! command.
8.6 Message Sequence Charts
In the following sections, the color scheme uses RED text as commands from a host to the module and
BLUE text as responses and prompts from the module to the host. Command/responses shown in
BLACK are associated with non-FTP related states.
Apart from FTP connection and disconnection scenarios, to avoid repetition, all message sequence
charts assume that the module is in a FTP-connected state. It also assumes that where “nnn FTP” occurs,
it can be read as “nnn OBX” if the command AT+OFT was used to initiate the command.