Microcontroller Bootloader Architecture and Dual Bank Flash Partitioning
Dual-bank flash partitioning enables fail-safe firmware updates by isolating execution to Bank A while writing and verifying new images on Bank B before reset.
Vector Table Remapping
Meaning
Execution redirection allows a processor to run interrupt service routines from a different memory location than the default reset address. This system configuration enables the system to dynamically switch between a bootloader interrupt table and an application interrupt table during runtime. By modifying the hardware mapping, the processor locates the correct function pointers when a hardware interrupt is triggered.
Hardware Mechanics
The system modifies a core system register or changes the configuration of the memory controller to redirect exception vectors. This redirection occurs seamlessly without requiring changes to the interrupt service routines themselves. The processor reads the new base address directly from the configured register whenever an exception occurs.
Boot Integration
The bootloader executes first and manages the initial startup tasks using its own vector table. Once the application image has been verified and is ready to run, the bootloader configures the redirection register to point to the application table. Control is then handed over to the application entry point.
Runtime Management
Redirection is also utilized during runtime execution of critical tasks from random access memory. When execution must be extremely fast and predictable, copying the vector table to random access memory and remapping the execution pointers eliminates flash memory access wait states. This configuration ensures real-time performance for critical communication or control loops.