General purpose flash memory
XLR PRO Radio Frequency (RF) Modem User Guide
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command), and other relevant information. This command is useful for generating a list of all XLR PRO addresses in a
network.
When a device receives the network discovery command, it waits a random time before sending its own response. The
maximum time delay is set on the ND sender with the NT command. The ND originator includes its NT setting in the
transmission to provide a delay window for all devices in the network. Large networks may need to increase NT to
improve network discovery reliability. The default NT value is 0x82 (13 seconds).
Neighbor polling
The neighbor poll command can be used to discover the XLR PROs which are immediate neighbors (within RF range)
of a particular node. This command is useful in determining network topology. The command is issued using the FN
command. The FN command can be initiated locally on a node using AT command mode or by using a local AT
command request frame. The command can also be initiated remotely by sending the target node an FN command
using a remote AT command request API frame. This is how the network map in XCTU is built.
A node which executes an FN command will send a broadcast to all of its immediate neighbors. All radios which
receive this broadcast will send an RF packet to the node that initiated the FN command. In the case where the
command is initiated remotely this means that the responses are sent directly to the node which sent the FN
command to the target node. The response packet is output on the initiating radio in the same format as a network
discovery frame.
General purpose flash memory
XLR PROs provide 119 512-byte blocks of flash memory which can be read and written by the user application. This
memory provides a non-volatile data storage area which can be used for a multitude of purposes. Some common
uses of this data storage include: storing logged sensor data, buffering firmware upgrade data for a host
microcontroller, or storing and retrieving data tables needed for calculations performed by a host microcontroller.
The General Purpose Memory (GPM) is also used to store a firmware upgrade file for over-the-air firmware upgrades of
the XLR PRO itself.
Accessing general purpose flash memory
The GPM of a target node can be accessed locally or over-the-air by sending commands to the MEMORY_ACCESS
cluster ID (0x23) on the DIGI_DEVICE endpoint (0xE6) of the target node using explicit API frames. (Explicit API frames
are described in the API Operation section.
To issue a GPM command, the payload of an explicit API frame should be formatted as follows:
Payload
byte offset
Number of
bytes
Field name
General field description
0
1
GPM_CMD_ID
Specific GPM commands are described below
.
1
1
GPM_OPTIONS
Command-specific options.
2
2
GPM_BLOCK_NUM
Block number addressed in the GPM. Specify multi-byte
parameters using big-endian byte ordering
4
2
GPM_START_INDEX
Byte index within the addressed GPM block. Specify multi-
byte parameters using big-endian byte ordering