XBee® Wi-Fi RF Modules
© 2013 Digi International, Inc. 66
7. API Operation
As an alternative to Transparent Operation, API (Application Programming Interface)
Operations are available. API operation requires that communication with the module
be done through a structured interface (data is communicated in frames in a defined
order). The API specifies how commands, command responses and module status
messages are sent and received from the module using a UART or SPI Data Frame.
Please note that Digi may add new API frames to future versions of firmware, so
please build into your software interface the ability to filter out additional API frames
with unknown Frame Types.
API Frame Specifications
Two API modes are supported and both can be enabled using the AP (API Enable)
command. Use the following AP parameter values to configure the module to operate in
a particular mode:
• AP = 1: API Operation
• AP = 2: API Operation (with escaped characters)
API Operation (AP parameter = 1)
When this API mode is enabled (AP = 1), the UART or SPI data frame structure is defined
as follows:
UART or SPI Data Frame Structure:
Any data received prior to the start delimiter is silently discarded. If the frame is not
received correctly or if the checksum fails, the module will reply with a module status
frame indicating the nature of the failure.
API Operation-with Escape Characters (AP parameter = 2)
When this API mode is enabled (AP = 2), SPI mode is not supported and the UART frame
structure is defined as follows:
UART Data Frame Structure - with escape control characters:
Escape characters
When sending or receiving a UART data frame, specific data values must be escaped
(flagged) so they do not interfere with the data frame sequencing. To escape an
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