image, backup and rom

Question

Hi all,

I'm using the Digi Connect ME 9210 with NET+OS Version 7.5.2.2.
I created a sample application with the capability to upload firmware using the web interface.

The message I got in the page is:

Upload a new firmware or ROM image into flash.
(A firmware image file must be called image.bin. A firmware backup/recovery image file must be called backup.bin. A ROM image file must be called rom.bin, spi_rom.bin, or romzip.bin.)

Can anyone explain me the difference from:

• image.bin
• backup.bin
• rom.bin

and how can I use them in my projects OR where can I find some documents to understand more regarding this topic?

Thank you very much.

Best regards

Answer 1

image.bin is your main application image. It is (decompressed) loaded into RAM and run by the boot loader.

backup.bin. Around NET+OS V7.4 Digi added the ability to load a backup image into FLASH. Why? Suppose your primary image (image.bin) gets corrupted. What do you do? When the boot loader is retrieving your primary image from FLASH it does a CRC test. IF this test fails, the bootloader assumes that your primary image is corrupt. IF you have a backup image loaded in FLASH the bootloader will then try to load the backup image into RAM and run it. The presumption is that your backup image has an ftp server as part of it allowing you to reload your primary image with a non-corrupt image.

rom.bin. This is the bootloader. In general its size should be limited to 64KB so that it fits within one FLASH sector. The bootloader's main task is to read your primary image from FLASH, decompress it, load it into RAM and run it. It also sets up chip selects and all sorts of other low level set ups.

Answer 2

Thank you for your answer.