In essence, the vector table is the . Without it, the CPU would have no idea how to respond to the myriad of internal and external events that make embedded systems powerful and responsive. Understanding the vector table is a fundamental step in moving from high-level Arduino coding to professional bare-metal embedded development.
In a microcontroller, the Vector Table is a specialized, read-only data structure located at a specific, predefined address in the memory map (usually the very beginning of flash memory, e.g., address 0x00000000 ). It is a sequential list of pointers (memory addresses), where each pointer tells the CPU where to find the Interrupt Service Routine (ISR) or exception handler for a specific event. what is vector table in microcontroller
// These are external variables defined in your linker script and code extern unsigned long _estack; // End of RAM address for the stack void Reset_Handler(void); // Your entry point or main() void NMI_Handler(void); void HardFault_Handler(void); void USART1_IRQHandler(void); // Your serial port handler // The actual vector table ((section(".vectors"))) void (* const g_pfnVectors[])(void) = (void (*)(void))&_estack, // 1. Initial Stack Pointer Reset_Handler, // 2. Reset Vector NMI_Handler, // 3. NMI HardFault_Handler, // 4. Hard Fault // ... other fault vectors ... USART1_IRQHandler, // 5. The USART1 interrupt handler // ... more peripheral vectors ... ; Summary | Aspect | Description | | :--- | :--- | | Definition | A fixed table of function pointers at a known memory address. | | Primary Role | To provide the CPU with the address of the correct interrupt handler. | | Critical Entries | Initial Stack Pointer, Reset Vector, Fault Handlers. | | Why it matters | Enables fast, deterministic response to real-time events (interrupts). | | Where it lives | Typically at the start of flash memory (e.g., 0x00000000 ). | In essence, the vector table is the