Operation
I/O support
Although samples may be taken every millisecond, IR*IT should be at least 20 milliseconds. This
allows time for OTA transmission and output on the serial port of the receiving module.
Destination node
On the destination node, the IU parameter enables the serial port to output I/O samples it receives. IU
is set to 1 by default. If IU is set and the destination node is not in Command mode, it displays
samples it receives on its serial port in API format. The AP parameter is ignored in this case.
Data format
The I/O sample is formatted as follows:
IT Mask Samples
1 byte 2 bytes 2 * number of samples
The IT field is described above.
The Mask is a bit field formatted as follows:
Reserved
A3 - A0
D8 - D0
3 bits
4 analog bits 9 digital bits
If you set any of the digital bits, then a digital sample follows the Mask.
For every analog bit that is set, there is a 10-bit sample using two bytes where A0 is included first and
A3 is included last.
The number of samples indicated by the mask is repeated IT times. The mask is not repeated.
The sending node sends I/O samples to the address specified by DH/DL. The receiving node displays
the samples as described above, providing API mode is enabled, the node is not in Command mode,
and the IU parameter is 1 (IU is 1 by default). If any of these are false, the I/O sample is discarded
without being displayed.
Change Detect I/O sampling
When you use the IC (DIO Change Detect) command to enable DIO Change Detect, DIO lines 0 - 7 are
monitored. When a change is detected on a DIO line, the following occurs:
1. This packet does not contain DIO8 and does not contain any analog samples. However, it does
contain a digital reading of the D0 - D7 pins configured for input or output, whether or not all
those bits are set in IC.
2. Any queued samples are transmitted before the change detect data. This may result in
receiving a packet with less than IT (Samples before TX) samples.
Change detect does not affect Pin Sleep wake-up. The D8 pin (DI8/SLEEP_RQ/DTR ) is the only line
that wakes a device from Pin Sleep. If not all samples are collected, the device still enters Sleep mode
after a change detect packet is sent.
Change detect is only supported when the Dx (DIOx Configuration) parameter equals 3, 4 or 5.
XBee/XBee-PRO S2C 802.15.4 RF Module User Guide
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ETC [ ETC ]
