ARM Cortex-M Timers and the Prevalence of Down-Counters In ARM Cortex-M microcontrollers, timers are a critical component for real-time operations, task scheduling, and peripheral control. A notable design choice in these systems is the use of down-counters rather than up-counters. This preference is rooted in both software efficiency and hardware optimization. Down-counters, which decrement from…
Cortex-M4F FPU Hard Fault During Float Literal Multiplication The Cortex-M4F processor, equipped with a Floating Point Unit (FPU), is designed to accelerate floating-point computations, making it ideal for applications requiring high-performance mathematical operations. However, a common issue arises when attempting to multiply a float variable by a float literal, resulting in a system crash. This…
Core 1 Fails to Execute from QSPI Flash with Incorrect Program Counter Jump When attempting to run bare-metal code on both cores of an ARM Cortex-A9 dual-core processor within an Intel Cyclone V SoC, Core 0 executes successfully from QSPI flash, while Core 1 fails to start correctly. Instead of jumping to its designated entry…
ARM Cortex-A53 Exception Handling and Mode Switching Fundamentals The ARM Cortex-A53 processor, part of the ARMv8-A architecture, supports multiple exception levels (ELs) and execution states (aarch32 and aarch64). Exception levels provide a hierarchical privilege model, with EL3 being the highest privilege level typically used for secure monitor code, EL2 for hypervisor functionality, and EL1 for…
ARM Cortex-M4 FPU Usage Verification Challenges When working with ARM Cortex-M4 processors that include a Floating-Point Unit (FPU), ensuring that all floating-point computations are performed using the hardware FPU rather than software libraries is critical for performance optimization. The Cortex-M4 FPU supports single-precision floating-point operations, and leveraging this hardware capability can significantly enhance the efficiency…
Core 1 Program Counter Misdirection to 0xFEBAF5E8 The issue at hand involves the failure of Core 1 to execute its designated code when booting from QSPI flash on an Intel Cyclone V SoC with an ARM Cortex-A9 dual-core processor. While Core 0 operates as expected, Core 1’s program counter (PC) incorrectly jumps to the address…
ARMv9 NEON Instruction Cycle Timing Documentation Gaps The ARMv9 architecture represents a significant evolution in ARM’s processor designs, introducing advanced features such as Scalable Vector Extension 2 (SVE2) and enhanced security capabilities. However, one area where developers face challenges is obtaining detailed cycle timing information for NEON instructions in ARMv9 processors. NEON, ARM’s advanced SIMD…
ARM Cortex-M4 Post-Silicon Compliance Testing Challenges Post-silicon compliance testing for ARM Cortex-M4 processors is a critical phase in the development lifecycle of embedded systems. This phase ensures that the silicon implementation of the Cortex-M4 core adheres to the architectural specifications and performs as expected under real-world conditions. The Cortex-M4, being a highly optimized processor for…
GIC Interrupt State Transitions and Linux Handling Flow The Generic Interrupt Controller (GIC) in ARM architectures plays a pivotal role in managing interrupts for multi-core systems. The GIC operates with a state machine that transitions interrupts through several states: Inactive, Pending, Active, and Active & Pending. Understanding these states is critical for diagnosing issues in…
ARM DSU Performance Evaluation Challenges and Goals The DynamIQ Shared Unit (DSU) is a critical component in modern ARM-based systems, responsible for managing shared resources such as L2 and L3 caches, power management, and core coordination in multi-core ARM Cortex-A and Cortex-R processors. Evaluating the performance of the DSU is essential for system architects and…