ARM Cortex-M0+ HardFault Handler and CONTROL Register Access When developing a HardFault handler for the ARM Cortex-M0+ processor, one of the challenges is accessing the CONTROL register value at the time the exception occurred. Unlike other registers such as R0-R3, R12, LR, PC, and XPSR, the CONTROL register is not automatically stacked by the processor…
ARM Cortex-A L2 Cache Maintenance Atomicity and Multi-Core Contention In ARM Cortex-A processors, the L2 cache is a shared resource among multiple cores, and its maintenance operations, such as Clean and Invalidate Line by Physical Address (PA), are critical for ensuring cache coherency and data integrity. However, when multiple cores attempt to perform L2 cache…
NMI Re-Entry Behavior in ARM Cortex-M7 During Critical Error Handling The Non-Maskable Interrupt (NMI) in ARM Cortex-M7 processors is designed to handle critical system errors that require immediate attention. Unlike regular interrupts, NMIs cannot be masked or disabled, ensuring that the processor responds to these events regardless of the current execution context. However, a critical…
AHB and APB Single Transfer Latency Comparison When comparing the Advanced High-performance Bus (AHB) and the Advanced Peripheral Bus (APB) in the context of a single transfer, it is essential to understand the fundamental architectural differences between these two bus protocols. Both AHB and APB are part of the ARM Advanced Microcontroller Bus Architecture (AMBA)…
ARM Cortex-R5 ETM Port and CTI Integration for Trace Functionality The ARM Cortex-R5 processor is a high-performance, real-time embedded processor designed for applications requiring deterministic behavior and high reliability. One of its key features is the Embedded Trace Macrocell (ETM) port, which facilitates real-time instruction and data tracing for debugging and performance analysis. However, the…
ARM Cortex-M4 CMSIS Header Function Definitions Causing Cross-Compilation Failures The core issue revolves around the challenges of compiling code that includes CMSIS (Cortex Microcontroller Software Interface Standard) headers on a non-ARM host system, specifically an Intel-based laptop. The CMSIS headers, particularly those for the Cortex-M4 and GCC, define a multitude of functions directly within the…
Cortex-R5 ACP Interface and DMA-Induced Data Coherency Corruption The Cortex-R5 processor features an Accelerator Coherency Port (ACP) interface, which is designed to maintain data coherency between the Level 1 (L1) and Level 2 (L2) memory systems, especially in scenarios involving Direct Memory Access (DMA) operations. The ACP interface consists of two primary components: the ACP…
ARM Cortex-R52 Exclusive Access Logic and Data Abort Triggers The ARM Cortex-R52 processor, designed for real-time and safety-critical applications, implements a sophisticated memory access mechanism that includes support for exclusive load/store operations. These operations are crucial for implementing atomic operations in multi-core or multi-threaded environments. However, the Cortex-R52 can raise an "Unsupported Exclusive Data Abort"…
ARM Cortex-M Cache Coherency Problems During Kernel Startup with FAULTMASK Enabled When initializing an ARM Cortex-M-based system, particularly during the kernel startup phase, developers often enable the FAULTMASK register to ensure that no interrupts disrupt the critical initialization process. This is a common practice in real-time operating systems (RTOS) to guarantee a deterministic startup sequence….
ARM Cortex-M Hardfault Due to Static Library Integration When integrating a static library into an STM32 project, a HardFault can occur due to various reasons related to memory alignment, stack overflow, or incorrect linker script configurations. The HardFault is a type of exception that occurs when the ARM Cortex-M processor detects a fault condition, such…