28 Questions
What is the primary use of the Process Stack Pointer (PSP) in ARM documentation?
Used by the base-level application code (when not running an exception handler)
What is the purpose of the Link Register R14 (LR) in the Cortex-M3 processor?
To store the return address when a subroutine or function is called
What is the significance of the program counter (R15) in the Cortex-M3 processor?
Due to pipelining, the value read from the program counter is different from the executing instruction by 4
What is the requirement for the least significant bit (LSB) of the target address when branching in the Cortex-M3 processor?
The LSB of the target address should be set to 1
What are the two operation modes of the Cortex-M3 processor?
Thread mode and Handler mode
What is the purpose of the two privilege levels in the Cortex-M3 processor?
To safeguard memory accesses to critical regions and provide a basic security model
What is the typical number of interrupt inputs on a Cortex-M3 microcontroller?
16 or 32
What is the purpose of the Non Maskable Input (NMI) signal on a Cortex-M3 microcontroller?
To warn the processor of critical events such as low voltage levels
What is the role of the NVIC in handling exceptions on a Cortex-M3 microcontroller?
To provide fault status registers to determine the cause of exceptions
How does the Cortex-M3 microcontroller determine the starting address of an exception handler?
Using a vector table mechanism
What is the characteristic of the vector table in a Cortex-M3 microcontroller?
It is relocatable
When can the NMI signal be activated on a Cortex-M3 microcontroller?
Any time, even right after the core exits reset
What is the impact on the processor mode when an exception occurs and the Control register bit 0 is zero?
The processor mode changes.
What happens to the processor mode and access level when an exception occurs and the Control register bit 0 is one?
Both processor mode and access level change.
What is the default stack arrangement after power-up in the Cortex-M3?
The MSP is used for both Thread mode and handler mode.
What is the purpose of using the PSP in Thread mode when the Control register bit 1 is 1?
To prevent a stack error in a user application from damaging the stack used by the OS.
What is the effect of using PSP in Thread mode on the automatic stacking and unstacking mechanism?
The automatic stacking and unstacking mechanism will use PSP.
Is it possible to perform read/write operations directly to the MSP and PSP without confusion?
Yes, it is possible.
What happens when the priority of the new interrupt is higher than the current level?
The interrupt handler of the new interrupt will override the current running task.
What is the advantage of the Cortex-M3 processor's vectored interrupt support?
The starting address of the interrupt service routine (ISR) is located from a vector table in memory, eliminating the need for software to determine and branch to the starting address.
Why can the priority levels of interrupts be changed by software during run time without risk?
Interrupts that are being serviced are blocked from further activation until the interrupt service routine is completed.
What is the benefit of the Cortex-M3 processor's ability to dynamically change priority levels?
It allows the system to adapt to changing conditions and priorities, ensuring that high-priority interrupts are attended to promptly.
What is the initial stack value that should be set for a stack memory range from 0x20007C00 to 0x20007FFF?
0x20008000
What is the broader goal of the Cortex-M3 processor's advanced features for interrupt handling?
To reduce interrupt latency, enabling the system to respond quickly to interrupts.
Why do vector addresses in the vector table have their LSB set to 1 in the Cortex-M3?
To indicate that they are Thumb code.
What is the reason for initializing the stack pointer after reset?
Because some exceptions (such as NMI) can happen right after reset, and the stack memory could be required for the handler of those exceptions.
What is the address of the boot code in the example given?
0x100
What happens after the reset vector is fetched in the Cortex-M3?
The Cortex-M3 can start to execute the program from the reset vector address and begin normal operations.
Learn about the different registers in ARM processor, including PSP, MSP, Link Register, and Program Counter. Understand their roles and how they interact with the processor's pipelined nature.
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