Question

I am looking for a mechanism to manipulate my eeprom image with a unique device id. I’d like to do this in a make file so that the device would automatically obtain a new ID and then update it to the data image, then flash it. In pseudocode:

wget http://my.centralized.uid.service/new >new.id
binedit binary.image -write 0xE6 new.id
flash binary.image into device

So first we get an id into a separate file, then we overwrite the image (from given offset) with the contents of this ID file. Then flash. But how to do the second part? I looked up bvi, which seems to have some scripting abilities, but I did not fully understand it, and to be honest vi always gave me the creeps.

Thanks for help beforehand!

Answer 1

(Full disclosure: I made the initial vote to close as a duplicate. This answer is adapted from the referenced question.)

Use dd with the notrunc option:

offset=$(( 0xe6 ))
length=$( wc -c < new.id )
dd bs=1 if=new.id of=binary.image count=$length seek=$offset conv=notrunc

You may want to try this on a copy first, just to make sure it works properly.