Flash Layout for Dual-Image OAD

This section will describe the method for placing images in internal flash when using dual-image OAD.

Constraints and Requirements for Dual-Image

The following points must be considered for Dual-Image OAD applications:

• The user application must be sufficiently small in order to fit into the flash layout system described below.

• Only one operational user application image may be stored in flash at any time.

Internal Flash Memory Layout

The internal flash of the device contains the active application, the download application and the MCUboot bootloader. Each application’s role is defined below.

Application Name	Description
MCUboot bootloader	Search for the proper image in FLASH Ensure validity and security of image before running Jump to the valid and newest image
Download application	Providing download area equivalent to the active application space
Active application	Active application Must implement OAD reset service Implementing customer defined behavior

The location of the download application varies depending on the flash size available for the selected device variant. This is done to maximize the active application space.

Refer to the linker command file (.cmd) define to further determine where precisely the each application is located.

Warning

The description above provides the starting flash layout for dual images.