OTA file system upgrades
OTA file system updates: OEM
Digi XBee® 3 802.15.4 RF Module User Guide
263
Use the
FS
command or MicroPython to load all of the files that you want to send onto the local
staging device.
Note
The staging device must have the same firmware version installed as the target device or the
file system will be rejected. Use the
VR
command to check the version number on both the staging
and target devices.
Download the file system image
Run the command
ATFS GET /sys/xbfs.bin
to download an image of the file system from the staging
device. The file is transferred using the YMODEM protocol. See
for more information on
downloading files using
FS GET
.
Pad the file system image
The file system image must be a multiple of 2048 bytes long before it is signed. Using hex editing
software, add 0xFF bytes to the end of the downloaded image until size of the file is a multiple of 2048
(0x800 in hex).
Calculate the image signature
Once the image has been padded to a multiple of 2048 bytes, it is ready to be signed. The ECDSA
signature should be calculated using SHA256 as the hash algorithm.
Assuming a public/private key pair has been generated as described in
, that the private key is named private.pem, and that the padded image is named
xbfs.bin
; this
can be done using OpenSSL with the following command:
openssl dgst -sha256 -sign private.pem -binary -out sig.bin xbfs.bin
sig.bin will contain the signature for the image.
Append the calculated signature to the image
The signature should be between 70 and 72 bytes, and it should be appended to the padded image.
Create the OTA file
Put the image into an OTA file that follows the format specified in
. The
file should consist of:
n
An OTA header
n
An upgrade image sub-element tag
n
The padded, signed image data
The OTA file must begin with an OTA header. See
for information on the format of the
header. The image type should be
0x0100
for a file system image upgrade.
The sub-element tag should come before the image data. The sub-element tag follows the format
described in section
6.3.3
of
. It consists of 6 bytes: the first 2 bytes are
the tag id and should be set to
0x0000
. The next 4 bytes contain the length of the file system image in
little-endian format.
Perform the OTA file system update
The process for performing an OTA file system update is the same as the process for performing a
FOTA upgrade, as described in
Over-the-air firmware/filesystem upgrade process for 802.15.4
. Note
