Hi Gilpin, Apologies if you have received multiple duplicates as my account in mailing list encountered problems today. Just to clarity - please use CfgDataDef.dsc (generated during the build) in the Build directory as input file to the Config Editor. Config Editor is used to modify configuration data in a GUI interface and most useful for 'merging' multiple board configurations (e.g., GPIOs) for the same platform. Thus one SBL image can support up to 32 boards, based on the platform ID. You may find more details in https://slimbootloader.github.io/developer-guides/configuration.html Regards, Aaron