STM32-Custom-Preemptive-Round-Robin-Scheduler

This repository contains the source code and documentation for a Custom Preemptive Round-Robin Task Scheduler on STM32, implemented from scratch without using any external RTOS. The project demonstrates low-level task management using ARM Cortex-M4 exception handling (SysTick and PendSV) and manual context switching.

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Features

• Preemptive Scheduling: Uses SysTick timer to generate periodic interrupts and trigger context switching via PendSV
• Manual Context Switching: Saves and restores task context (R4–R11) using Process Stack Pointer (PSP)
• Round-Robin Algorithm: Cycles through multiple tasks with equal priority for fair CPU allocation
• Task Delay Mechanism: Implements tick-based blocking/unblocking using a global tick counter
• Idle Task: Executes when no other task is ready
• Critical Section Handling: Uses PRIMASK to avoid race conditions during scheduling

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Components Used

• STM32 Nucleo Development Board
• Onboard LEDs (GPIO Output)

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🧰 Tools & Technologies

• STM32CubeIDE – Development and debugging
• STM32 HAL – Peripheral abstraction
• ARM Cortex-M4 – Exception handling (SysTick, PendSV, PSP/MSP switching)
• STM32CubeMX-Peripheral configuration and initialization code generation