I/O support
Legacy support
Digi XBee® 3 802.15.4 RF Module User Guide
89
Legacy support
By default, the XBee 3 802.15.4 RF Module is configured to operate in a legacy configuration. This
provides network and application compatibility with
devices. Use
to determine which outgoing API frames are emitted
and what I/O lines are used for sampling.
On the source node,
AO
affects:
n
Which Digital I/O lines are sampled
n
What sample frame type is used for outgoing transmissions
On the destination node,
AO
affects:
n
How incoming XBee 3 sample frames are interpreted and what API frames are emitted
Previous 802.15.4 firmwares on the XBee S1 and XBee S2C hardware had a limited set of I/O lines
available. Valid DIO lines on these devices are from D0 through D8; I/O samples are transmitted over
the air using a standard I/O sample packet
. These platforms do not have
an
AO
command and always output sample data in a legacy format if possible.
For the XBee 3 platform, digital I/O has been enhanced to be in parity with DigiMesh and Zigbee. You
can now enable up to fourteen digital inputs for sampling: D0 through P4 as long as
AO
is not set to
2
.
In order to support these additional I/O lines, an
is sent over the air,
which is not compatible with the S1 or S2C.
By default, the XBee 3 802.15.4 RF Module is configured to operate in a legacy configuration
with
AO
set to
2
. This allows you to sample D0 through D8. If you configure D9 through P4 as digital
I/O, they are not sampled unless you set
AO
to
0
or
1
.
For new designs, we recommend setting
AO
to
0
or
1
), which allows you to use
additional I/O lines for sampling and easily allows you to switch to Zigbee or DigiMesh, as the API and
I/O functionality are identical.
This table illustrates the various configuration combinations that are possible and the expected
output:
Source
Source
AO
value
Destination
Destination
AO value
Data
format
API frame on receiver
XBee 3 0 or 1
XBee 3
0 or 1
Enhanced
I/O Data Sample Rx Indicator frame -
XBee 3 0 or 1
XBee 3
2
Legacy
RX (Receive) Packet: 64-bit address IO
frame - 0x82
/
XBee 3 0 or 1
S1 or S2C
N/A
N/A
N/A
XBee 3 2
XBee 3
0 or 1
Legacy
RX (Receive) Packet: 64-bit address IO
frame - 0x82
/
XBee 3 2
S1 or S2C
N/A
Legacy
RX (Receive) Packet: 64-bit address IO
frame - 0x82
/