SPRUJ17I March 2022 – August 2025 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
This section describes different stages involved in initialization, starting from SoC power-on to loading and running an application. Following are the stages involved as shown in the Figure 5-1:
Hardware Startup Process
RBL Process
SBL Process
Hardware Startup Process :
Preinitialization: Must provide necessary hardware inputs for the device to function i.e., power, clock, control connections and the boot configuration pins. All the control and boot configuration pins must be held at the desired logical levels.
Power, clock, reset ramp sequence: Specific sequence that is applied by the power-management chip(s)
Hardware Startup requires an understanding of the process of configuring system interface pins i.e., pads on the device, which have software-configurable functionality. This configuration is an essential part of the chip configuration and is application-dependent. This chapter discusses these system-interface pins, the associated configuration registers, and memory structures that are vital for the proper initialization of the device.
RBL (ROM Bootloader) Process:
R5F ROM: ROM code running on R5F0 core is responsible for identifying the boot interface, downloading, and executing the Secondary Boot Loader (SBL) software.
HSM ROM: HSM ROM code runs on M4 core performs image integrity/authentication and it allows or forbids the initial software (SBL) execution.
R5F ROM and HSM ROM primarily focuses on executing the SBL.
ROM Code Overview describes RBL process in detail.
SBL (Secondary Bootloader) Process :
Initial software or SBL: Primary software responsible for configuring SoC, that loads and passes control to the application software.
HSM RunTime or TIFS-MCU: Firmware running on secure island i.e Cortex M4. This will enable security services as needed by the application software.
R5F Runtime or Application: FreeRTOS/ NO RTOS or bare-metal application which runs on main processor(s).
HSM ROM and SBL collectively boot the HSM RunTime, and the SBL and HSM RunTime collectively boot the R5F Run Time/ Application
Figure 5-1 Initialization and Boot Process