What Is Vector Table In Microcontroller !full! Jun 2026

When you press the "Reset" button on a microcontroller development board, magic seems to happen. The LEDs light up, the screen initializes, and your code begins to run. But how does the processor know where your code starts? How does it know what to do when a timer overflows or when you press a button?

This is the most important entry. When the MCU is powered on or reset, the hardware automatically looks at this specific memory address. It contains the starting address of your main program. Without a reset vector, the CPU is "blind" and won't know where the first line of code is. 2. The Stack Pointer (Initial Value) what is vector table in microcontroller

Microcontrollers have internal hardware modules like Timers, ADCs (Analog-to-Digital Converters), and UARTs (Serial communication). These modules need a way to get the CPU's attention. When you press the "Reset" button on a

// 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 ... ; How does it know what to do when

By default, the vector table sits at address 0x0000_0000 . However, in complex systems, developers use a feature called the to move the table to a different location in Flash or even into RAM (for faster execution).