We would like to be able to do remote field updates to the DM642 boot
flash. Has anyone done this.
I was thinking we could have a base bootloader locked in flash that never
will be overwritten that brings interface up, then runtime image can be in
another sector of flash that can be overwritten. I am just worried if box is
powered down during flash programing we may have problems.
thanks much,
-Bill
Reply by Mike Dunn●June 22, 20052005-06-22
Hello Bill,
You can get there [as long as the FLASH doesn't get into some
'stupid mode']. Off the top of my head...
1. never modify the boot code or 'update FLASH code'.
2. put some signature info into your app at a constant offset from the
beginning of the 'first application sector'. This can be as
simple or complex as you need. The table could look something like:
<begining of app flash>
start_pattern1
start_pattern2
last_address_used
sum or crc from end_of_table+4 to last_address_used
firmware_revision (int)
app_entry_point
end_of_table
3. sanity check firmware revision
4. check start_pattern1 [generated by algo from f/w rev]
5. check start_pattern2 [generated by algo from start_pattern1]
6. check end_patterns 1&2 [XOR of start_patterns at last 2
addresses]
7. run crc or checksum
8. if you get here, you are 'good to go'; if problem, post error
and beg for reload
mikedunn
b...@comcast.net wrote:
We would like to be able to do remote field updates to the DM642 boot
flash. Has anyone done this.
I was thinking we could have a base bootloader locked in flash that never
will be overwritten that brings interface up, then runtime image can be in
another sector of flash that can be overwritten. I am just worried if box is
powered down during flash programing we may have problems.
thanks much,
-Bill
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