Firmware Fallback Setup and Slot Management#

Initial Setup - Using Default SDK Examples#

The three reference examples provided in the wiseconnect SDK needs to be loaded in a certain sequence, when using the Firmware Fallback feature for the first time in a device. The following image shows how to load the M4 and NWP firmware.

Initial Setup reference imageInitial Setup reference image

Important: After the Initial Setup, firmware images must be updated only via OTA. Usage of any other methods to flash the firmware images would disrupt the firmware fallback feature.

Generating Firmware for Different Slots#

Firmware fallback feature allows users to have two different M4 firmware images in the flash. These firmware images must be generated with proper flash address, configured in the <project_name>/autogen/linkerfile_SoC.ld file.

  1. M4 updater application, which is responsible for updating the slots, will be present at the default M4 application start address. Linkerfile address would be 0x8202000

  2. M4 slot-A and slot-B application start addresses are to be decided by the user based on the application size and M4 space remaining

  3. Flash addresses of the reference examples in wiseconnect SDK are tabulated below:

Example Start Address End Address Size in Hex Size in Decimal Linkerfile representation
M4 Fallback updater 0x8202000 0x827EFFF 0x07D000 512000 bytes (500 KB) 
MEMORY
{
    rom (rx) : ORIGIN = 0x8202000,
    LENGTH = 0x7d000
    ram (rwx) : ORIGIN = 0xc,
    LENGTH = 0x2fbf4
}
M4 Slot-A example 0x827F000 0x842EFFF 0x1B0000 17268472 bytes (1.69 MB) 
MEMORY
{
    rom (rx) : ORIGIN = 0x827f000,
    LENGTH = 0x1b0000
    ram (rwx) : ORIGIN = 0x400,
    LENGTH = 0x2f800
}
M4 Slot-B example 0x842F000 0x85DFFFF 0x1AF000 1720320 bytes (1.64 MB) 
MEMORY
{
    rom (rx) : ORIGIN = 0x842f000,
    LENGTH = 0x1af000
    ram (rwx) : ORIGIN = 0x400,
    LENGTH = 0x2f800
}