Architectures and Processors

ARM Cortex-M1 SP and PC Register Modification Errors in Keil When working with the ARM Cortex-M1 processor, modifying the Stack Pointer (SP) and Program Counter (PC) registers is a critical task, especially when developing a bootloader. However, developers often encounter challenges when attempting to modify these registers using inline assembly in the Keil development environment….

ARMv8 Multi-Core Cache Line Updates and Coherency Mechanisms In ARMv8 multi-core systems, cache coherency is a critical aspect of ensuring data integrity across cores. When multiple cores access and modify the same memory location, the system must guarantee that all cores observe a consistent view of memory. This is particularly important when cores have private…

ARMv8-A CPSR Write Side Effects and Instruction Synchronization In ARMv8-A architecture, particularly when operating in AARCH32 state, writing to the Current Program Status Register (CPSR) is a critical operation that can have significant side effects on the Processor Element (PE) behavior. The CPSR register controls various aspects of the processor’s operation, including the processor mode,…

ARM Cortex-A8 Secure Monitor Mode Transition Challenges The ARM Cortex-A8 processor, as implemented in the TI AM3358 Sitara SoC, provides a secure execution environment through the Secure Monitor Mode (SMM). This mode acts as a gateway between the normal world (non-secure state) and the secure world (secure state). The transition to Secure Monitor Mode is…

Secure State Transition and Stack Pointer Behavior During NSC Function Calls When a Non-Secure Callable (NSC) function is invoked within a non-secure SVC interrupt service routine, the ARM Cortex-M processor undergoes a state transition from non-secure to secure state. This transition involves several critical architectural mechanisms, including the handling of stack pointers and processor modes….

TCM Arbitration Hazards During Read-Modify-Write Operations Tightly Coupled Memory (TCM) in ARM processors is designed to provide low-latency, high-bandwidth memory access for critical code and data. However, the arbitration mechanism governing access to TCM ports can introduce subtle hazards, particularly during read-modify-write (RMW) operations. These hazards arise due to the prioritization of access requests from…

Power and Performance Trade-offs in ARM Cortex-M Processors for Medical Applications When designing an implantable medical device, the selection of an ARM processor involves a careful balance between power consumption, performance, and reliability. Implantable devices, such as pacemakers, neurostimulators, or drug delivery systems, operate under stringent power constraints, often limited to 1.5 to 2.5 watts….

Cortex-M1 Reset Vector and Boot Sequence Misconfiguration The core issue revolves around the Cortex-M1 processor failing to boot correctly when programmed onto an Artix-7 FPGA unless a debugger is connected to manually start the application. This behavior suggests a fundamental misconfiguration in the boot sequence or reset vector setup. The Cortex-M1, like other ARM Cortex-M…

Cortex A9 Coresight TMC State Machine and STS Register Behavior The Cortex A9 Coresight Trace Memory Controller (TMC) is a critical component for debugging and tracing operations in ARM-based systems. The TMC operates in several states, including Disabled, Enabled, and Ready, which are governed by a state machine defined in the ARM documentation. The Status…

Real-Time Performance Limitations with Preempt-RT Patch on ARM Cortex-A57 The ARM Cortex-A57 is a high-performance processor core designed for applications requiring both computational power and energy efficiency. However, when implementing real-time systems on platforms like the NVIDIA Jetson TX2, which utilizes the Cortex-A57, developers often encounter challenges in achieving hard real-time performance. The Preempt-RT patch…