Hi David,
I suppose the problem is in the image format. MCUXpresso SDK examples by default provide bootable image including FCB (flash configuration block). This format is not supported in SEC tool yet, and you need to remove FCB from the image - see chapter 6.5.1 in User Guide for detailed instructions.
BTW, in the tool, the error message is displayed as a tooltip, in this case, I suppose error message is "Bootable image is not supported, image without header must be used"
And yes, determination of start address from ELF format produced by MCUxpresso IDE is supported in SEC tool.
Hope this helps
Regards,
Marek
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