<p><img src="https://cdn.hashnode.com/res/hashnode/image/upload/v1682190704652/45553e83-3731-4aa8-b581-4af99997a38d.png" alt class="image--center mx-auto" /></p>
<p><a target="_blank" href="https://developer.arm.com/documentation/ddi0337/h/programmers-model/processor-core-register-summary">reference</a></p>
<h2 id="heading-stack-pointer-in-cortex-mx-process-will-point-to-either-spprocess-or-spmain">Stack pointer in cortex Mx process will point to either SP_process or SP_main.</h2>
<h2 id="heading-what-are-spprocess-and-spmain"><strong>What are SP_process and SP_main?</strong></h2>
<ul>
<li><p>SP_process = PSP(Process Stack Pointer) = Task's private stack</p>
</li>
<li><p>SP_main = MSP(Main Stack Pointer) = Kernel stack</p>
</li>
</ul>
<p>RTOS scheduler decides which task to run every sysTick. A higher-priority task will be scheduled and during the execution of the task, it will use its stack which is called SP_process. r13(SP) will point to SP_process.</p>
<p>When ISR executes, it will use SP_main. r13(SP) will point to SP_main.</p>


![](https://cdn.hashnode.com/res/hashnode/image/upload/v1682190704652/45553e83-3731-4aa8-b581-4af99997a38d.png align="center")

[reference](https://developer.arm.com/documentation/ddi0337/h/programmers-model/processor-core-register-summary)

## Stack pointer in cortex Mx process will point to either SP\_process or SP\_main.

## **What are SP\_process and SP\_main?**

* SP\_process = PSP(Process Stack Pointer) = Task's private stack
    
* SP\_main = MSP(Main Stack Pointer) = Kernel stack
    

RTOS scheduler decides which task to run every sysTick. A higher-priority task will be scheduled and during the execution of the task, it will use its stack which is called SP\_process. r13(SP) will point to SP\_process.

When ISR executes, it will use SP\_main. r13(SP) will point to SP\_main.

Stack Pointer in Cortex Mx processor

Stack pointer in cortex Mx process will point to either SP_process or SP_main.

What are SP_process and SP_main?