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Operation
The Commissioning Button
XBee Wi-Fi RF Module User Guide
38
CTS flow control
The
FT
command allows you to specify how many bytes of data can be queued up in the serial
transmit buffer before the device asserts CTS low. The serial receive buffer can hold up the 2100
bytes, but
FT
cannot be set any larger than 2083 bytes, leaving 17 bytes that can be sent by the host
before the data is dropped.
By default,
FT
is 2035 (0x7F3), which allows the host to send 65 bytes to the device after the device
asserts CTS before the data is dropped. In either case, CTS is not re-asserted until the serial receive
buffer has
FT
-17 or less bytes in use.
RTS flow control
If you send the
D6
command to enable RTS flow control, the device does not send data in the serial
transmit buffer out the DOUT pin as long as RTS is de-asserted (set high). Do not de-assert RTS for
long periods of time or the serial transmit buffer will fill. If the device receives an RF data packet and
the serial transmit buffer does not have enough space for all of the data bytes, it discards the entire
RF data packet.
If the device sends data out the UART when RTS is de-asserted (set high) the device could send up to
four characters out the UART port after RTS is de-asserted. This means your application needs to de-
assert RTS by the time its receive capacity is within 4 bytes of full.
The Commissioning Button
The XBee Wi-Fi RF Module supports a set of commissioning and LED functions to help you deploy and
commission devices. These functions include the Commissioning Button definitions and the associated
LED functions.
To enable the Commissioning Button functionality on TH pin 20/SMT pin 33, set
to
1. The functionality is enabled by default.
Use the
CB
command to simulate button presses in software. Send
CB
with a parameter set to the
number of button presses to perform. For example, if you send
CB2
, the device performs the action(s)
associated with two button presses,
CB4
is four button presses. See
.
It provides two different services:
n
Two button presses in fast sequence invoke WPS; see
n
Four button presses in fast sequence force the device into Soft AP Provisioning mode by
clearing the SSID and security parameters. It also ensures that Soft AP mode is enabled. After
the four button presses clear the security parameters, they are NOT written. Send a separate
, if desired.
The following features can be supported in hardware. Connect a pushbutton and an LED to XBee Wi-Fi
RF Module pins 33 and 28 (SMT), or pins 20 and 15 (TH) respectively to support Commissioning Button
definitions and the associated LED functions.