Flash Layout for On-Chip OAD

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

Constraints and Requirements for On-chip OAD (stack library)

In order to perform an On-chip OAD the target system must have:

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

• User app functionality is lost while performing OAD (Persistent app is running)

Internal Flash Memory Layout

The internal flash of the device contains the active user application, the user application’s stack, the persistent application, the persistent application’s stack, and the secure bootloader. Each application’s role is defined below.

Note

As we have assumed the stack-library approach, the stack images referenced below are a part of each application image (i.e. the user and persistent apps have their own dedicated stack)

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
Persistent application	Providing lightweight application that implements the OAD profile
Stack (2)	BLE protocol stack implementation
User application	User application Must implement OAD reset service

The user application pictured above is responsible for the following:

• Implementing the protocol stack definition of the OAD reset service

• Implementing customer defined behavior

The persistent application pictured above is responsible for the following:

• Implementing the protocol stack definition of the OAD service

• is permanently resident on the device

Note

Based on different device, the address of each component listed above might vary. The exact address can be found in the persistent application linker file.

Listing 205. cc23x0_app_freertos.md - Flash address for various components

#define PERSISTENT_BASE 0x6000
#define NVS_BASE        0x30000
#define APP_BASE        0x34000
#define MCU_HDR_SIZE    0x100
#define MCU_TLV_SIZE    0x120
#define MCUBOOT_SIZE    0x6000
#define NVS_SIZE        0x4000
#define MCU_OVERHEADS (MCU_HDR_SIZE + MCU_TLV_SIZE)