Echelon FTXL - Manual (Page 205)

FTXL User’s Guide 193
should also inform the user of its state.
During this stage, the FTXL device should verify that the application to
be downloaded can run on the device platform (using the FPGA ID or
similar mechanism), and verify that the application image is from a
trusted source (for example, by using an encrypted signature).
2. Download the application.
A reliable and efficient data transfer mechanism should be used. The
interoperable file transfer protocol (FTP) can be used, treating the entire
application image as a file.
The download utility and the application must support long flash write
times during this portion of the download process. The FTXL application
should update the flash in the background (see Download Capability
within the Application on page 193), however, it might be necessary for
the protocol to define additional flow control to allow the FTXL
application to complete flash writes before accepting new data.
3. Complete download.
The application download utility informs the current application that the
download is complete. The FTXL application should verify the integrity
of the image, and either:
a. Accept the image, and proceed to the final steps below.
b. Request retransmission of some sections of the image.
c. Reject the download.
4. Boot the new application.
To boot the new application, you must implement a custom boot loader
(or boot copier) so that the Nios II processor can load the new application
and restart the processor with the new image. See the Altera application
note AN 458: Alternative Nios II Boot Methods for information about
creating a custom boot loader.
Important: For the duration of the first three steps, the application must be
running, the FTXL LonTalk protocol stack must be started, and the FTXL device
must be configured.
Application Download Utility
This tool needs to read the application image to be loaded, and run the
application download protocol described in Custom Application Download
Protocol on page 192. You can write the utility as an LNS Plugin or as any type
of network-aware application.
Download Capability within the Application
Your application must implement the custom application protocol, and provide
sufficient non-volatile storage for the new application image. The application
also must tolerate time consuming writes to flash during the transfer. At a